PRIMARY AND SECONDARY IGNITION PATTERNS
Warning:Ignition coils create high voltage.It can be dangerous,so avoid getting too close to ignition parts when the engine is running.Make your connections when the engine is OFF.and keep your distance when the engine is running.Even some primary is high enough to stop a "Pacemaker".
Also:Do not run engines with Secondary Ignition HT leads "open circuit".Make sure they are grounded to the engine through a spark plug,grounding wire, or a a spark tester.
PRIMARY VOLTAGE PATTERNS:
Set up a lab scope or ignition oscilloscope to view the primary ignition pattern (in parade or display mode) on your lab scope,with the engine warmed up and idling.
Record the average FIRING VOLTAGE (or "STEP UP VOLTAGE") for each cylinder in the chart below.Some variation is normal,just pick the average.
300 volts +.
Record the average BURN VOLTAGE for each cylinder in the chart below
50-60 volts.
Record the average BURN TIME in milliseconds for each cylinder in the chart below
1.4 - 1.6 ms
Record the average DWELL TIME for each of the cylinders in the chart below.What unit of measurement are you using to measure the dwell time?
7.5 ms
Are all these primary ignition voltage readings normal?
Yes.
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CYL 1 CYL2 CYL3 CYL4 PRIMARY IGNITION
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300V + 300V+ 300V+ 300V+ FIRING VOLTAGE
55V 55V 55V 55V BURN VOLTAGE
1.5ms 1.5ms 1.5ms 1.5ms BURN TIME
7ms 7ms 7ms 7ms DWELL TIME
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Primary ignition waveform of a single cylinder.
The ignition waveform of the four cylinders
Discuss what the primary display or parade patterns emphasizes for diagnosis.What can it help you see?
This shows the actual voltage needed to fire each spark plug (Firing Voltage)
The duration of each spark (Spark Line)
It shows the condition of the coil (oscillations)
Shows the voltage spike
Shows the burn time.
Shows the burn voltage.
from the above waveform,i can check the 6 stage of ignition pattern in 4 cylinders
battery voltage,dwell time,firing kv,spark burn time,continuing,oscillation.
1.The Battery Voltage is the initial input voltage.This voltage is supplied constantly by the alternator.It can range from 13.6 volts to 14.4 volts.
If the alternator is not charging,then definitely there will be different results.
The vehicles performance will go down.
2 is the dwell part of the pattern.This is where the coil is actually turned on by the vehicles control module.The coil is building up a strong magnetic field to fire the spark plug during this part of the pattern.
3 is the part of the pattern where the spark is actually firing.The initial spark uses the most voltage,as the spark is generated less voltage is needed to maintain the spark and the voltage drops.the amount of time the spark stays active and the amount of voltage needed to keep the spark going can give you clues as to whats going on inside the cylinder.
A low starting spark line could indicate that the spark plug could be oil fouled,that a short in the plug wire is present,or that the cylinder compression is low.
5 to 6 is the part where the coil is turned off,and the magnetic field that the coil has generated is now collapsing.
You can get an idea what condition your coil is in by watching the oscillations just after the spark plug has fired.
If there are fewer than 4 oscillations,as this part of the pattern then there could be some shorting in the coil.
SECONDARY VOLTAGE PATTERNS
Set up your ignition oscilloscope or lab scope to view the secondary ignition patterns on your lab scope,with the engine warmed up and idling.(Use parade mode or individual mode on each different cylinder,depending on scope available.)
Record the average FIRING ORDER or the SET UP VOLTAGE for each cylinder
Record the average BURN TIME for each cylinder
From the ignition pattern reading we had achieved from the test we had done we can see that the firing voltages were 5KV in all the four cylinders.And we saw the burn time of 1.4 ms in all four cylinders.This reading proves that the ignition in this engine is normal.All the values are in range with the manufacturer's specifications.
We got a good result.
Secondary output is shown by presenting each secondary trace,side by side;
To ease the measurement the vertical trace lines are broadened.
Normally the pattern is displayed in order that the spark plugs are fired.
This trace shows clearly the voltage needed initially to fire each spark plug.
If conditions are normal,the height of each prominent verticals is similar.
Do a Snap Acceleration(don't damage the engine by revving too high for too long) and record in the chart below how high the FIRING VOLTAGE (KV) went under Snap Acceleration.
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CYL1 CYL2 CYL3 CYL4 Secondary Ignition
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5KV. 5KV. 5KV. 5KV. Firing Voltage (KV)
1.4ms 1.4ms 1.4ms 1.4ms Burn Time (ms)
7KV. 7KV. 7KV. 7KV. Snap Acceleration
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Are all these Snap Acceleration secondary ignition voltage readings normal?
Yes.
If you can safely do this,(with the engine stopped),gently disconnect one spark plug wire,and short to the engine with a jumper wire.
Which cylinder number did you short?
Cylinder number 4.
Start the engine and let it idle (for only a short time).Record the new FIRING VOLTAGE and BURN TIME FOR ALL THE CYLINDERS
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CYL1 CYL2 CYL3 CYL4 Secondary Ignition
(One cylinder grounded)
..................................................................................................................................
6 6 6 4 Firing Voltage (KV)
1.4ms 1.4ms 1.4ms 1.4ms Burn Time (ms)
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The Secondary Ignition waveform of a single cylinder.
The Secondary Ignition waveform of the four cylinders.
Picture of #4 spark plug out.And the engine running.
The spark plug wire grounded to the engine.
1.
2.
Pictures 1. and 2. clearly show the difference between a normal ignition waveform and a waveform which is showing a sign of a malfunctioning ignition system.We can clearly see how the waveform is different in cylinder number four.This is because the spark plug lead to cylinder # 4 has been removed.And the difference in the two waveforms is because the gap we had set between the plug and the ground was more in the first picture.And the waveform is smaller in the second picture because the gap between the plug and the ground is less.That means that the spark has to travel less to ground.
The KV is very low.
This is a very good example for us to understand why we should always have good spark plugs in our vehicles.The bigger gap between the spark plug and the ground requires a longer burn time.
That could be one of the reasons why the vehicle may be taking a bit more fuel than before.
And may lose a bit of power.
Stop the engine and attach a spark tester to another spark plug wire.Start the engine and let it idle (for only a short time).Record the new Firing Voltage and Burn Time for all the cylinders in the chart below.
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CYL#1 CYL#2 CYL#3 CYL#4 Secondary Ignition
(Spark tester on one cylinder)
.....................................................................................................................................
5KV 5KV 5KV 9KV Firing Voltage (KV)
1.5ms 1.5ms 1.5ms 1.5ms Burn Time (ms
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Stopped the engine.
Removed the spark tester.Replaced the spark plug wire back in the engine.
Started the engine again.
Engine back to normal
Everything normal.Engine running smoothly.
No warning lights are ON.
The engine Idle is normal.There is no mis-firing.
The rpm is steady.That proves that all the plugs are firing.
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OXYGEN SENSORS ON VEHICLE
The Oxygen Sensor is the device in the engine that is measuring the amount of oxygen in the exhaust.It is also known as the Lambda sensor.
One example i know of is the Jaguar cars.I had to work on a 2002 Jaguar car.Got the ECU scanned.It had multiple errors coming up.And one of these errors was a Lambda sensor.The scanner was not picking up an oxygen sensor,but a Lambda sensor.
The sensor is mounted in the exhaust manifold.And all the exhaust gases pass over it.As the the heat and the exhaust gases pass over it,it takes readings.And sends these readings to the ECU.The ECU then processes this information and adjusts the engine controls accordingly.
Some vehicles seem to have two oxygen sensors.But the bottom ones are normally the heater.
The oxygen sensor is closed loop feedback controlled.
The oxygen sensor is in constant communication with the ECU to determine if the ratio of the air/fuel mixture igniting in the combustion chamber is rich or it is lean.
Oxygen sensors are very sensitive.It should not be dropped.
The oxygen sensor can be checked using a OBD scanner,with an oscilloscope,and also with a multimeter.The oxygen sensor should be replaced to the vehicle manufacturer's specifications.There are many different threads on the oxygen sensors.Should be alert when replacing a oxygen sensor.
Normally the engine check light comes ON if the oxygen sensor is no good.But i saw a Nissan pulsar that was doing just the opposite.This was on Warsame's car.Even with the oxygen sensor wiring plug OFF,the engine check light was OFF.And most of the readings we took of the input sensors were normal.A bit strange result.
*Even if the Oxygen sensor is faulty,the car will still start.
*May have a warning light ON in the dash.
*The vehicle we used to test the oxygen sensor was a 1995 Toyota Cynos.
It's an automatic car with 4A-FE Engine in it.Registration number CHC 775.
Locate Oxygen Sensor
Locate an oxygen sensor on your vehicle.Describe where it is located:
The Oxygen Sensor is located on the Exhaust Manifold on this engine.
The oxygen sensor
It is visible from the top.
It's in the middle of the exhaust manifold.On the side.
It's in a very good spot.It can be accessed easily.Can use a spanner to open it if the sensor needs to be changed someday.
Some vehicles have the Oxygen Sensor in a very difficult to reach place.
You have to open a lot of things to get to the sensor.
How many wires for this oxygen sensor?
This Oxygen Sensor has got 1 wire only.
Normally this is the signal wire.
Can't be said the same for all Oxygen Sensors.Some European designed sensors are totally opposite to the Japanese designed sensors.
This 1 is a Japanese sensor.So it's the signal wire.
Record the colours for each of the wires at the sensor side of the connector (not the ECU side of the connector).Then list the use of the wires.Usually a black or blue wire will be the Oxygen Sensor signal,Grey may be the sensor ground.Heater power and ground are often white.But there are other colours.You may have to consult a wiring diagram.
Colour Use or Purpose
Black Signal Output
What type of Oxygen Sensor is this?
The sensor on this engine is the Zirconium switching sensor.
Back probe the Oxygen Signal Wire with a pin and connect to an oscilloscope.
Check that you are connected to the Oxygen sensor signal:Run the engine and check that you are seeing a signal.Connected ok?
Yes.It's connected properly.
And we got a signal.
How high does the voltage go?
0.819 Volts.
How low does the voltage go?
0.169 Volts.
What is the average voltage?(Some oscilloscopes have functions that will calculate the average for you).
0.49 Volts.
How many "Cross Counts" does the signal have in 10 seconds? (One cross count is when it goes from high to low,or from low to high)
List here:7.
If the signal is not cycling normally,describe what the signal does:
Not in a closed loop.
The sensor will not respond.
The ECU cannot control the fuel injection.
Watch and Record Oxygen Signal pattern at Idle rpm.Let the engine warm up and enter a closed loop so you see a normal cycling pattern.You may have to hold the rpm at about 2500 for half a minute to go into closed loop.Then let the rpm come down to Idle.
How high does the voltage go?
0.759 Volts.
How long does the voltage go?
0.413 Volts.
What is the average voltage?
0.49 Volts.
How many "Cross Counts" does the signal have in 10 seconds?(One cross count is when it goes from high to low,or from low to high).
List here:5.
Make this Oxygen Sensor go rich by accelerating once or twice.(The fuel system should normally make the system go rich when you do a sudden acceleration).Push on the accelerator quickly but don't let the rpm go high enough to damage the engine.
The signal should go over 0.85 Volts.
How high does the Oxygen Sensor voltage go?
The reading that we got was 0.954 Volts.
If this signal is not going high normally,describe what the signal does:
That means that the exhaust gases are in a lean condition.This is the information that is supplied from the oxygen sensor and processed by the ECU.
Make this Oxygen Sensor go lean by doing a sudden deceleration.Gently run the rpm up to about 3000 and let the rpm drop suddenly.The fuel system should make the system go lean on deceleration.The signal should go below 0.2 Volts.
Discuss how a Zirconium Oxygen Sensor works:
Discuss how good or bad this Oxygen sensor is.What about it functions well or is it faulty?Can it accurately tell the ECU how rich or lean the exhaust is?
Lambda sensors produce a voltage that recognises the amount of unburnt oxygen in the exhaust.
When hot (at least 250 degrees),the Zirconium dioxide element in the sensor's tip produces a voltage that varies according to the amount of the oxygen in the exhaust compared to the ambient oxygen level in the outside air.The greater the difference,the higher the sensors output voltage.Sensor output ranges from 0.2 volts (lean) to 0.8 volts (rich).A perfectly balanced or "stoichiometric" fuel mixture of 14.7 parts of air to 1 part of fuel gives an average reading of around 0.45 volts.The Lambda sensor's voltage doesn't remain constant.It rocks back and forth from rich to lean.Every time the voltage reverses itself and goes from high to low,or vice versa,it's called a "cross count".A good oxygen sensor on a injection system should fluctuate from rich to lean about 1 time per second.If the number of cross counts is lower than this,it tells you that the oxygen sensor is getting sluggish,and needs to re-placed.
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FLASH CODES
The vehicle we used to check for the Flash Codes was a 1995 Toyota Cynos Juno.It's an automatic 2 door sedan with 4A-FE engine in it.
Warning:Be careful working around engines and exercise caution to avoid injury.
NOTE:The engine check light must be working.
Flash/Blink Codes
Find a engine/vehicle that you have the workshop manual with the correct procedure and codes to diagnose the flash codes.
Create a fault in the EFI system.
Using the workshop manual follow the procedure to extract the codes,explain briefly what is the procedure.
We used a Toyota Cynos.This has the 4A-FE engine in it.The engines in our practical class are mostly Toyota 4A-FE.All these engines in the workshop have a manual.
The procedure to extract codes for this particular engine is by bridging the pins E1 and TE1.
Turn Ignition OFF.Bridge pin E1 and TE1.
Once this is done,turn Ignition ON.
Check the "check engine light".It will blink.Count the number of times it blinks.
Example:If it blinks 3 times and there is a short pause and then it blinks 4 times,then that means that the code is 34.Then you can check the code in the manual.Or you can google it up.
I was fixing a Toyota Starlet.Was fixing the power windows.Saw the check light ON.
Bridged the E1 and TE1 Pins.
The engine check light blinked 5 times then stopped.It then blinked 2 times.
That meant that the code was 52.Googled up the code.
It was the Knock Sensor.
Told the customer what to change.I should increase my charges now.!
BACK PROBING
Testing for the right and left indicator wires.
Using the test lamp.
Should always be careful not to damage the wires.
Or your finger as well.If you push hard on the wire,and you got your finger behind the wire as a support,you will injure yourself if you slip on the wire.
Also if you are checking for wires,make sure the ground is good.
Many times a steel piece in the vehicle is not grounded.
And if you don't see any power,you may think the unit you testing is faulty.
And mis-diagnose the fault.
..................................................................................................................................................... BLOG # 4
ANTI LOCK BRAKING SYSTEMS LAB WORKBOOK
The Anti-Lock Brake System (ABS) is a braking system that is in all the cars produced today.
It's a safety feature because it doesn't lock up the wheels when you brake hard.
It allows the driver to have steering control while still braking hard.
The ABS decreases the vehicle stopping distance.The efficiency of the braking will be different on different surfaces.You will brake differently on a sealed road and brake differently on a gravel road.
When you brake hard,you can feel the brake pedal vibrating
There are a few types of ABS systems.There is 4 channel type which has all four wheels with seperate brake lines.There is three channel ABS system,where three lines control the four wheels.Two for the front and one line controlling the rear wheels.And we have the one channel ABS,where one line controls the rear wheels.
When you go car shopping,you will see all the car yards have the the car features written on the wind screen.And all will have ABS on it.Everyone wants a safe car.And cars with ABS will sell.
Some cars have have a simple ABS system.Easy to work on.And some vehicles use a much complex system.Some sports cars have massive power.And they accelerate really fast.And they need to have really good braking systems to be able to stop as well.
That is the reason why the sports cars have big brake rotors and big brake discs.The brake pads apply braking pressure over a bigger area.And is easier to stop the vehicle.
Some of the rotors even have grooves cut on them.This is done to stop the rotors from getting too hot when braking.
The trucks have Engine braking.This system blocks the exhaust pipe and tries to stall the engine.And slows the truck.Good system because on load just the brakes won't be enough to stop the truck.
The ABS system works when the engine is running.And when the engine is running,all the vehicles power is supplied by the alternator.That is the reason that we see about 14 volts and not 12 volts for the ABS power input.
So if the alternator is not charging,and the vehicle is being driven,the ABS system is not getting sufficient power to operate.
That's why many times when the warning lights come ON,it's the alternator that's faulty.
That means that if the alternator is not charging,all the power is being supplied by the battery.And the battery is not charging.It is dis-charging.
After a while of driving if the brakes are slammed hard,the ABS may not even work.Because the battery doesn't have enough power to run the car and supply high current to the ABS Pump.
The alternator does play a very important role in the vehicle.
That's what happened to Steve's car.His warning lights used to come ON.
And he thought there was a loose connection in the dash.
But it was his alternator that wasn't charging.He changed the regulator and all the problems gone.
I was fitting an alarm system in a 2005 Mazda ATTENZA.
Very neat car.Had only done 103000 kms.Kept in a good condition.
Everything was fine.Found all the required wires for the alarm.
Hooked up the alarm system.Doors were locking and un-locking.
But when i started the car,the ABS Warning light and the Engine check light were ON.
The ABS and the Engine check light ON.
Tried a few times to turn the car OFF and then start it again.
But the lights were still ON.
The idle was fine.No engine vibrations.
Finished everything with the alarm.Assembled the dash trim.
Then i took the car for a drive.
While driving,the ABS warning light went OFF.
I'm not sure why the light came ON.
Maybe the system sensed an error when i disconnected one of the plugs to find the vehicle indicator wires.
Or maybe i used the normal test lamp when finding the alarm wires.Normally the L.E.D Computer safe tester should be used.
It is common for the ABS light to turn ON when working on the vehicles brakes.
It normally goes OFF when the vehicle is driven
ABS warning light OFF.
Called the customer.Told her that the car was ready.
Disconnected the positive battery terminal.
She came to pick her car up in 35 minutes.
Told her she had some issues in her car because the Engine check light was ON.
She said she had the car for 2 1/2 years.And the Engine check light has been ON for some time.
I told the customer that we can fix the problem.She said she spent $2000 trying to fix it.
The mechanic that works on the car changed the Knock sensor.the ABS sensors and the AIR BAG sensor.But the problem doesn't go away.
The technician must have been just guessing and doing things trial and error method.
Connected the battery wire again.The Engine Check Light was OFF.
The customer was really happy.I guess i should have charged her a bit extra for fixing the problem.
Haven't heard back from the customer.
Maybe the problem is really fixed.
The Engine check light still ON before dis-connecting the battery wire
ABS light is ON.But the problem is not in the ABS system.It is mechanical.Collapsed wheel bearing.
If someone is driving a manual vehicle and suddenly has to brake hard to avoid an accident,and if the driver doesn't press the clutch if the vehicle is in gear then the engine will stall.
And if the engine stalls and goes OFF,the brake pedal will go hard.This is because there is no vacuum going to the brake booster.
Not sure if the ABS will still work 100 %.
May work at a slightly less rate.
And if the ABS is not working at all,then there is still brakes but the normal way.
The wheels will lock up.
Off-car ExercisesThink about ABS Repair:
Misconceptions,The ABS system should be simple and robust,with the Module/ECU/Controller almost never giving any trouble.
Below are some possible causes for damaging an ECU.
- Spiked by careless welding,i.e.MIG welding without disconnecting the battery.
- Enclosure seal damaged and with obvious sign of water ingress
- Obvious signs of mechanical damage to the enclosure
- Faults are much more likely to be with the connections or sensors.True
Discuss how these ECU issues should be incorporated into diagnostic practices to test an ABS system:
Sometimes many mechanics mis-diagnose ABS faults just by looking at the ABS sensor.
If the sensor looks good and none of the wires are broken,it doesn't mean that the sensor is still good.
And the other thing i have noticed is that guys use the normal test lamps to see if the power is coming to the sensor.But they don't realise that the ABS sensor is not a solenoid,and will not show any voltage by turning the test lamp bulb ON or OFF.
Most of the ECU damage is caused by back-probing the test lamp in wires that shouldn't be played up with.
This is when a simple job becomes really costly.And the poor customer has to pay the bill.
ABS Wiring and Operation
Lets review the ABS system to remind ourselves what components are included and how they should work.
- Brake rotor
- ABS Sensor
- Tooth Wheel
- Hydraulic Modulator
- Master Cylinder
- Brake Caliper
Brake Booster
Wiring Diagram Practice
There are a number of components in the ABS system that are also used for fuel injection.These are mostly speed sensors e.g.wheel speed and engine speed.
Using the wiring diagram in the workshop manuals identify the wheel speed sensors and list their wire colours for each sensor
Front right : B,W Black,White
Front left : G,R Green,Red
Rear left : L,P Blue,Pink
Rear right : Y,BR Yellow,Brown
On the ABS wheel sensor what is the reason for the braided wire?
- To protect the wires from the Electro Magnetic Field.
- Also to protect the wires from vibration,and heat.
- Also to make it easier to identify the ABS wires.
Identify and list all the fuses that are used by the ABS circuit.
- 10 Amp -GAUGE
- 15 Amp -STOP
15 Amp -ECU IG
20 Amp -DOME
FL MAIN, F 14 50 AMP ABS
Identify the earths for the ABS control unit and ABS motor.Their wire colours and what pin numbers.
ABS ECU GROUND PINS =10B,7B
ABS MOTOR =PIN 23
On the wiring diagram for the ABS actuator,identify which solenoids control which wheel cylinder.Then note the wire colours and pin numbers
Front Right Wheel
Pin number:2B,6B
Wire colour:R/W,R/G = Red/White,Red/Green
Front Left Wheel
Pin number:3B,7B
Wire colour:L/R,L/W = Blue/Red,Blue/White
Rear Left Wheel
Pin number:1B,5B
Wire colour:BR/W,BR/R = Brown/White,Brown/Red
Rear Right Wheel
Pin number:4B,8B
Wire colour:G/B,G/Y = Green/Black stripe,Green/Yellow stripe
Using the picture as a guide,what is the correct condition of the inlet and outlet solenoid valves under normal braking?
B. Inlet valve Open Outlet valve Closed
What is the correct condition of the inlet and outlet solenoid valve when the ABS is operating to reduce wheel pressure?
C. Inlet valve Closed Outlet valve Open
What is the correct condition of the inlet and outlet solenoid valves when the ABS is operating to hold brake pressure?
D. Inlet valve Closed Outlet valve Closed
What is the correct condition of the inlet and outlet solenoid valve when the ABS is operating to increase wheel brake pressure?
B. Inlet valve Open Outlet valve Closed
The ABS Pump on a Honda CRV we worked on
The ABS valves
In the four cases above,state when the ABS motor will be working?
The ABS will be working when the Inlet valve is open and the Outlet valve is closed.
Sometimes when the braking gets a bit sluggish,many guys just straight away think it's the ABS pump.
Or even the sensors.But the valves get blocked also.It is common.
ABS Demonstrators
Locate the wiring diagram for your demonstrator vehicle.Find the ABS wheel speed sensor pin-out connections to the ECU on the wiring diagram and the demonstrator.Record which ECU wires go to which wheel speed sensors:
Left front ECU Pin # 4 and 5
Left rear ECU Pin # 7 and 9
Right front ECU Pin # 11 and 21
Right rear ECU Pin # 24 and 26
By looking at the wiring diagram,what type of speed sensor is this?
This is a four channel ABS system.
It is a magnetic or inductive sensor.
Describe how it works:
The sensor is mounted on the vehicle suspension.Near the brakes.The tooth wheel on the brake hub constantly gives information to the sensor while the vehicle is moving.This signal is sent by the sensor to the ABS ECU.
The wheel speed sensors constantly monitor and send information to the ABS ECU.But normally the ABS function kicks in after the vehicle is travelling over 20 km/hr
Some ABS ECU units even have built-in self diagnosing systems
Locate an oscilloscope.Turn it ON and set it up to be fully operational.What oscilloscope are you using?
Scope.
AC Range.
Are all the waveforms exactly the same?
No.
What are the differences and what can cause these differences between the waveforms?
Different voltages
Different gap size
Dirt and Debris between the sensor and the teeth on the wheel.
With the wheel speed sensors spinning,measure AC volts with a multi-meter and record here:
Left front 3.2 V
Left rear 4.09 V
Right front 2.79V
Right rear 2.87V
Can a multi-meter be as accurate in finding problems with the wheel speed sensors as an oscilloscope?
No.
Discuss what the oscilloscope could find that the multi-meter can not find and why:
The oscilloscope can take very small readings as well.And very fast signals as well.
But the multimeter cannot pick up the fast signals.
ABS Relays
The ABS Relays
Looking at the wire colours and the Bosch Relays,i can say this ABS system is off a European car.
One thing we noticed with the ABS Relays is that the Pins were quite big.And the Relay itself is bigger than the normal relays.The reason for this must be because the when the ABS pump is activated,it requires a large current.And to avoid damage to the relay,the manufacturer uses a big high output relay.
It looks like a 50 amp or even higher current rated relay.
Record the name of the relay or switch that powers up the ABS ECU:(look at the wiring diagram)
K 39 4 Pin Relay
Record the name of the relay or switch that powers up the ABS Pump:(look at the wiring diagram)
K 100 4 Pin relay
ABS Pump Relay
Record the name of the relay or switch that sends power to the ABS HCU solenoids:(look at the wiring diagram)
K 38 5 Pin Relay
Relay wire identification:(Consult the wiring diagram)
What is the ECU Pin number for the wire that brings in the power to the ABS ECU?
Pin # 1 (sw,rt)
What is the ECU pin number,or other number,for the wire that controls the relay for the ABS ECU?
Pin # 15 (Ignition Switch---Ignition ON)
What is the Pin number for the wire that brings in the power to the ABS Pump?
Pin # 13 (from the ECU)
What is the pin number,or other number,for the wire that controls the relay for the ABS Pump?
Pin # 28 (from ECU)
Most probably (-ve)
The waveform shows the cycle of the ABS pump when in operation.
The ABS pump doesn't stay ON full time.
When the brakes are applied hard,the ABS ECU gets the power from the brake switch.
The pump turns ON and OFF really fast.
That's the reason we can feel the vibration on the brake pedal when the ABS System is activated
The first ABS Relay Waveform that we recorded.This is wrong.
The pattern is wrong.It was done on wrong setting....................
In this graph we can see the ABS Relay turn ON
But it stays ON.It is not switching.
And the ABS pump is not activating.
The ABS Pump and the ABS Relay switch together when activated
Waveform of the solenoids working.
We can see the solenoids turning ON and OFF.
This is switching at a fast rate.
This is because the ABS works really fast.
Measure the air gap for each wheel sensor.
State the air gap and visual condition of each wheel sensor
*We used a brass Feeler Gauge
*Steel feeler gauge shouldn't be used
Front Right
0.016 inch 0.406 mm
The sensor is in good condition.
Front Left
0.026 inch 0.660 mm
The sensor is in good condition.
Rear Right
0.016 inch 0.406 mm
The sensor is in good condition.
Rear Left
0.022 inch 0.958 mm
The sensor is in good condition.
Using a Scan Tool
The car that we were doing the testing on was a 1998 Mazda Familiar.
It didn't have any numbers on the wind screen.I saw the details on the seat belt.
All cars have their manufacture date on the seat belt.
This is a Unitec vehicle.# 8129
Plugged in the scan tool.
This is the result that i got on the scan tool
1. 12. B 2200,B 2600 i MPV:SYSTEM NORMAL
ELSE :WSS, SR (LF)-OPEN OR SHORT
2. 41. WSS,SR (LF)-OPEN OR SHORT
42. WSS , SR (LF) -OPEN OR SHORT
3. 51. FAIL SAFE RELAY-OPEN OR SHORT
11 B 2200 B 2600. MPV:BRAKE LAMP SW
4. ELSE:WSS, SR (RF) -OPEN OR SHORT
The reason we were getting all these codes is because this vehicle is a training car.And it has been played with.
1.
2.
3.
Pictures 1,2 and 3 are off a 2002 PEUGEOT 206 ABS Motor.It was not working.We changed the whole motor.Picture 2 is the old unit and picture 3 is the new unit.Its second hand.But the ABS system worked fine after it was fitted.
CAN - Multiplexing Worksheet
1.0 CAN Waveform on Oscilloscope
1.1 Locate the Range Rover or other suitable vehicle with easily accessible CAN system twisted wires.What vehicle do you have?
The vehicle that we did the tests on was a 2001 RANGE ROVER VOGUE
1.2 Locate a twisted wire pair.Describe where the wires are located:
The twisted CAN wires that we tested was located in front of the ABS Pump.There was a plug connected to the ABS Pump.The twisted wires were connected to the plug.
1.3 Record the waveform of one of the wires below:
(Make sure your time is small enough so you don't have "aliasing".)
Colour of wire:YELLOW / BROWN STRIPE
Time per division:10 MICRO SECONDS
Voltage per division:2 VOLTS
1.4 Record the waveform of the other wire in the twisted pair.
In this picture we can the waveform of the two wires together.
It is like a mirror reflexion.
Colour of wire:YELLOW / BLACK STRIPE
Time per division:10 MICRO SECONDS
Voltage per division:2 VOLTS.
1.5 What is aliasing?Describe it.
In signal processing and related disciplines,aliasing refers to an effect that causes different signals to become indistinguishable (or aliases of one another) when sampled.
It also refers to the distortion or artifact that results when the signal reconstructed from samples is different from the original continuous signal.
*Information from:WIKIPEDIA
Aliasing is like a ghost image appearing on a image.
Like a shadow.Making all the images not so clear.
The two wires waveform.The frequency is quite fast.
1.6 How do you know these waveforms are not "aliasing"?
The waveforms that we had recorded were clear.
There wasn't any other blurred images with it.
1.7 In the 1.3 waveform above,what is the main voltage on the line?
2.85 VOLTS.
What is the other voltage on the line,when the voltage is pulled up or down to "talk"?
1.9 VOLTS.
1.8 In the 1.4 waveform above,what is the main voltage on the line?
2.9 VOLTS.
What is the voltage on the line,when the voltage is pulled up or down to "talk"?
4.8 VOLTS.
1.9 Observe the signals in 1.3 and 1.4 above with your voltmeter.Compare it with DC volts or AC volts setting.Which setting would tell you if the signal is switching.Explain:
We tested the signals using a multi-meter.
The multi-meter was set on AC range.
The reading we got was 5.3 Volts/AC and 0.4 Volts/AC.
The DC range setting measures the voltage at a set point.
The AC range setting measures the signal when switching.
2.0 Scan Tool Observations
2.1 Find a vehicle that will show CAN system operation on a scan tool (such as the Range Rover.)
Which vehicle are you using?
We were using a 2001 Range Rover Vogue
Which scan tool are you using?
We were using AUTOBOSS.
Very good scanner.Touch screen.And easy to use.
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Pictures 1. and 2. show the data that we saw on the scanner.
It shows all the vehicle controls.
The scanner is plugged in.
Now we are in the vehicles CAN System.We can see the electrical controls.We even can operate most of these electrical components from the scanner.We were operating the power windows from the scanner.
Using the scanner to operate the window
We tried to look for the 2001 Range Rover Vogue details on the scanner.But these details were not coming up on the screen.So we used the BMW details.And it worked.Can see on the actual wiring as well that the BMW parts are being used.
There are a lot of wires that are twisted together in pairs.
Mostly the twisted wires indicate that the wires are CAN wires.
But in this case these are not the CAN wires.These wires are the wires from the car stereo.
This vehicle has got a built-in factory amplifier.
If the head unit (stereo) is changed to a after-market unit,there won't be any sound coming from the speakers.
This is because the wires from the factory radio go to the amplifier,and then from the amplifier the wires are connected to the speakers.
That means that all the twisted wires are not CAN wires.
HONDA MULTIPLEXING BOARD WORKSHEET
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All the pictures above are of the the Honda Multiplexing system.
