1. When does ABS, ESP or TCS system do its self diagnosis check?
When the ignition is first turned on and the engine started. The light in dash cluster will light up then turn off after a few seconds.
2. If a vehicle is entering a sharp left hand turn, and starts to under-steer, what might the ESP system do to regain vehicle stability? Assume the vehicle has 4 channel ESP.
The front left brake will be activated to pull the car to the left.
3. If a vehicle is entering a sharp right turn and starts to oversteer, what might the ESP system do to regain vehicle stability? Assume the vehicle has 4 channel ESP.
The back left brakes will activate to pull the back in from its slide.
Then if the car over-corrects the front right will activate to help stabilize.
4. When does the TCS light come on?
At start-up and when loss of traction is detected, also when a fault is detected by the ECU.
5. When does the ABS light come on?
At start-up and when the wheels lock under heavy braking causing the ABS to start working.
Also when a fault is detected.
6. When does the ESP light come on?
At start-up and when the car loses traction enough to induce a slide, also when a fault is detected.
7. The customer is braking lightly to stop for a stop sign. They feel the brake pedal pulsing.
Discuss what could be wrong and how you would test the system.
bad brake pads
warped brake rotors
Pull ABS Relay, peform brake test to see if fault is ABS related.
8. The brake fluid is low in the resovoir. Which light will come on in the dash? Discuss repairs.
handbrake light
check brake pads for wear
9. A shop is repairing a vehicle with an ABS light on and code 31 for right front wheel speed sensor. They replace the sensor, and the vehicle returned with the ABS light still on. Discuss what they could have done wrong and what they should do now.
Use a scan tool
Check connections
ECU
Air gap of sensor
Pulse Ring
10. An ABS light is on in the dash. The owner of the car decides to just remove the bulb (plans to sell car). Discuss what can be the result of his actions.
new owner crashes with no ABS
No WOF
Past owner goes to court for tampering with a vehicle causing death or injury.
11. In the workshop, you found you had to connect both test leads from the oscilloscope to the inductive ABS wheel sensor wires to get a good pattern. Discuss why.
You are missing an earth at the solenoid, requiring the 2 two leads.
12. You are working on a vehicle that has two solenoids per channel on a four channel ABS system. You find the wires that go to the right front brake inlet valve and you ground the earth wire with the engine running. Will you be able to turn the right front tire if it is raised off the ground? ( vehicle is not in park ) Discuss why or why not.
The solenoid is negatively switching so the brakes will be applied.
13. This vehicle has rust on a right front wheel speed sensor and toothed wheel that causes the wheel to have to spin faster in order to develop the right amount of voltage to be read by the ECU module. Discuss how will this affects the braking of the vehicle?
There will be uneven brake pressure applied as the ECU will be reading the RF wheel as moving too slow.
14. What is the vehicle doing when the Traction control program acts or intervenes?
Rear wheels lose traction.
15 What is the vehicle doing when the Electronic stability program acts or intervenes?
The car is sliding out of control.
Monday, September 20, 2010
CAN
Locate the Range Rover or other suitable vehicle with easily accessible CAN system twisted wires. Which vehicle do you have? ( Year, make, and model).
Land Rover 2003
Locate a twisted wire pair. Describe where the wires are located:
It is located under the bonnet on the passengers side and connected to the ABS Control Unit
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
Time per division: 2 Seconds
Voltage per division: 0.5V
Record the waveform of the other wire in the twisted pair.
Colour of wire: BlackTime Per Division: 20ms
Voltage per division: 1V
What is aliasing? Describe it: When an image is viewed, a reconstruction is performed by a display, and by the eyes and the brain. If the resolution is too low, the reconstructed image will differ from the original image, and an alias is seen. Aliasing can be caused either by the sampling stage or the reconstruction stage; these may be distinguished by calling sampling aliasing pre-aliasing and reconstruction aliasing post-aliasing
How do you know these waveforms are not "aliasing"?
They are clear and easy to read
In the 1.3 waveform above, what is the main voltage on the line?
2.5V
What is the other voltage on the line, when the voltage is pulled up or down to "talk"?
1.5V
1.8 In the 1.4 waveform above, what is the main voltage on the line?
2.5V
What is the voltage on the line, when the voltage is pulled up or down to "talk"?
3.5V
Observe the signals in 1.3 and 1.4 above with a voltmeter. Compare it with DC volts or AC volts setting. Which setting would tell you if the signal is swtching. Explain:
YellowBrown: DC = 2.352V and AC = 0.23V
YellowBlack: DC = 0V and AC = 0.002V
This observation shows how they are switching on and off.
Find a vehicle that will show CAN system operation an a scan tool (such as the Range Rover).
Which vehicle are you using?
Land Rover 2003
Which scan tool are you using?
Autoboss
What different functions are available on the scan tool to examine the CAN system?
Primary ignition
Secondary ignition
Multimeter
DSO
Auto DSO
Engine Analyzer
Setup
List the different systems that are controlled by CAN? (note which are high speed and which are low speed)
High - ABS , TSC, ECU, TCU, ESP.
Low - TV, Windows, Body Control Unit, Central Door Locking, Cooling Fans, Alarm, Steering, Seats and Fuel Pump.
On-Car Exercises
Connect a Scan Tool to the vehicle you are testing and bring up the transmission information. (You may find it in the engine section.)
Hanatech
Mitsi Galant 1996
First gear solenoids:
2nd / OD
LR / OD
2ND / LR
LR / UN
The torque converter clutch didn't come on until 1400rpm in 3rd gear.
It remained off from start up to 1400rpm in 3rd gear.
When the brake pedal was pressed, the slip RPM spiked from 33RPM to 204RPM
Gear 1st 2nd 3rd 4th
LR Solenoid 0.00% 99.47% 99.47% 99.47%
UR Solenoid 0.00% 0.00% 0.00% 99.47%
2nd Solenoid 99.47% 0.00% 99.47% 0.00%
OD Solenoid 99.47% 99.47% 0.00% 0.00%
DCC Solenoid 0.00% 0.00% 49.76% 77.11%
Which scan tool are you using:
Hanatech
Which vehicle are you using:
Mitsi Galant 1996
2.2 With the vehicle safely on jack stands or a lift (use the proper worksheet for that), safely drive the vehicle to allow it to shift up and down through the gears. View the solenoids as the vehicle shifts up and down. Record which solenoids are on in which gears:
With the shift lever in Drive or Overdrive:
First gear solenoids:
2nd / OD
Second gear solenoids:
LR / OD
Third gear solenoids:
2ND / LR
Fourth gear Solenoids:
LR / UN
View the Torque Converter Clutch as you safely drive the vehicle. Record when it is when it is on or off:
Torque Converter Clutch ON:
The torque converter clutch didn't come on until 1400rpm in 3rd gear.
Torque Converter Clutch OFF:
It remained off from start up to 1400rpm in 3rd gear.
What effect does the brake pedal have on the Torque Converter Clutch operation?
When the brake pedal was pressed, the slip RPM spiked from 33RPM to 204RPM
Create Shift Chart for your vehicle. Based on the operation of the shifting above, create a shift chart that describe what solenoids are on in which gear:
Gear 1st 2nd 3rd 4th
LR Solenoid 0.00% 99.47% 99.47% 99.47%
UR Solenoid 0.00% 0.00% 0.00% 99.47%
2nd Solenoid 99.47% 0.00% 99.47% 0.00%
OD Solenoid 99.47% 99.47% 0.00% 0.00%
DCC Solenoid 0.00% 0.00% 49.76% 77.11%
Electronic Tranmissions and Scan Tools
Vehicle: Mitsubishi Galant
Year: 1996
Engine Size: 2.0
Abbreviations
Sensors:
Air Charge Temperature
Air Conditioning Clutch
Brake On/Off Switch
Profile Ignition Pickup
Coolant Temperature Sensor
Mass Air Flow Sensor
Manual Lever Position Sensor
Output Shaft Speed Sensor
Transmission Oil Temperature Sensor
Throttle Position Sensor
Vehicle Speed Sensor
PCM
Electronic Pressure Control Solenoid
Modulated Converter Clutch Control Solenoid
Shift Solenoid SS1
Shift Solenoid SS2
Self Test
Wiring Diagram
Shift Chart
Shift Solenoids
Which solenoids are "on" when this vehicle is shifted into Drive and starts out in first gear?
1-2 / 2-3
Which solenoids are "on" when this vehicle automatically shifts into second gear?
-- / 2-3
Which solenoids are "on" when this vehicle automatically shifts into third gear?
-- / --
Which solenoids are "on" when this vehicle automatically shifts into fourth gear?
1-2 / --
Shift Solenoid Malfunction: Describe what would happen if none of the solenoids came "ON". Could the vehicle drive? What gear would it be in? How fast could the vehicle go? Could it have the Power to climb a hill?
Yes the car would drive but would be stuck in third gear, the vehicle would accelerate very slowly until it reached the appropriate speed for that gear, and so would not have the low-down power required to climb a hill.
Codes: Pick two transmission codes out of repair information, and describe what the code means and what malfunction would cause the code:
Code: LR Solenoid Valve Open
This is because the transmission cable is unplugged and is not powering the shift solenoids so therefore the solenoid is stuck open
Code: UD Solenoid Valve Open
This is because the transmission cable is unplugged and is not powering the shift solenoids so therefore the solenoid is stuck open as with the above error code.
Diagnosis
For each code listed above, discuss what tests you culd run to diagnose the problem:
1st Problem Testing: Tried shifting by sticking in drive or using the tip-tronic shift but the vehicle stayed in third gear with the transmission cable still unplugged.
2nd Problem Testing: Connections needed to be checked, obviously it was the transmission cable being unplugged that was creating the fault so with the cable re-connected the car began shifting gears like normal.
Year: 1996
Engine Size: 2.0
Abbreviations
- PCM - Powertrain Control Module
- TCC - Torque Converter Clutch
- TPS - Throttle Position Sensor
- ECT - Engine Coolant Temperature
- VSS - Vehicle Speed Sensor
- PSA - Transmission Range Fluid Pressure Switch Assembly
- TTS - Transmission Temperature Sensor
Sensors:
Air Charge Temperature
Air Conditioning Clutch
Brake On/Off Switch
Profile Ignition Pickup
Coolant Temperature Sensor
Mass Air Flow Sensor
Manual Lever Position Sensor
Output Shaft Speed Sensor
Transmission Oil Temperature Sensor
Throttle Position Sensor
Vehicle Speed Sensor
PCM
Electronic Pressure Control Solenoid
Modulated Converter Clutch Control Solenoid
Shift Solenoid SS1
Shift Solenoid SS2
Self Test
Wiring Diagram
Shift Chart
Shift Solenoids
Which solenoids are "on" when this vehicle is shifted into Drive and starts out in first gear?
1-2 / 2-3
Which solenoids are "on" when this vehicle automatically shifts into second gear?
-- / 2-3
Which solenoids are "on" when this vehicle automatically shifts into third gear?
-- / --
Which solenoids are "on" when this vehicle automatically shifts into fourth gear?
1-2 / --
Shift Solenoid Malfunction: Describe what would happen if none of the solenoids came "ON". Could the vehicle drive? What gear would it be in? How fast could the vehicle go? Could it have the Power to climb a hill?
Yes the car would drive but would be stuck in third gear, the vehicle would accelerate very slowly until it reached the appropriate speed for that gear, and so would not have the low-down power required to climb a hill.
Codes: Pick two transmission codes out of repair information, and describe what the code means and what malfunction would cause the code:
Code: LR Solenoid Valve Open
This is because the transmission cable is unplugged and is not powering the shift solenoids so therefore the solenoid is stuck open
Code: UD Solenoid Valve Open
This is because the transmission cable is unplugged and is not powering the shift solenoids so therefore the solenoid is stuck open as with the above error code.
Diagnosis
For each code listed above, discuss what tests you culd run to diagnose the problem:
1st Problem Testing: Tried shifting by sticking in drive or using the tip-tronic shift but the vehicle stayed in third gear with the transmission cable still unplugged.
2nd Problem Testing: Connections needed to be checked, obviously it was the transmission cable being unplugged that was creating the fault so with the cable re-connected the car began shifting gears like normal.
ABS Wheel Speed Sensors
On the vehicle that you have been assignment does it use analogue or digital wheel sensors?
Analogue
How did you conclude that the wheel speed sensors were analogue or digital?
The Sensors produced an AC waveform making it analogue and had 2 wires
Measure the air gap for each wheel sensor.
State the air gap and the visual condition of each wheel sensor.
Front Right: Gap of 0.152mm, Sensor had accumulated brake dust and dirt on it.
Front Left: Gap of 0.152mm also, as well as brake dust and dirt on the sensor
Rear Right: Sensor is covered
Rear Left: Sensor is covered
Using an oscilloscope connect it to a wheel sensor and record the pattern shown, If the sensor is a Analogue sensor then just connect then probe and spin the wheel. If the sensor is digital you will need to have the iginition on before you turn the wheels.
This pattern is analogue
Using the frequency scale on a multi-meter. Turn the wheel at proximately the same speed as in the above test. Note the frequency and compare it to the graph you drew above.
Frequency: 125.30Hz
No observations
Using a Scan Tool
Using a scan tool go to the ABS live data screen and note all the sensors, data and what it is telling
This information could not be obtained.
Analogue
How did you conclude that the wheel speed sensors were analogue or digital?
The Sensors produced an AC waveform making it analogue and had 2 wires
Measure the air gap for each wheel sensor.
State the air gap and the visual condition of each wheel sensor.
Front Right: Gap of 0.152mm, Sensor had accumulated brake dust and dirt on it.
Front Left: Gap of 0.152mm also, as well as brake dust and dirt on the sensor
Rear Right: Sensor is covered
Rear Left: Sensor is covered
Using an oscilloscope connect it to a wheel sensor and record the pattern shown, If the sensor is a Analogue sensor then just connect then probe and spin the wheel. If the sensor is digital you will need to have the iginition on before you turn the wheels.
This pattern is analogueUsing the frequency scale on a multi-meter. Turn the wheel at proximately the same speed as in the above test. Note the frequency and compare it to the graph you drew above.
Frequency: 125.30Hz
No observations
Using a Scan Tool
Using a scan tool go to the ABS live data screen and note all the sensors, data and what it is telling
- Left Front WSS 0 km/h
- Right Front WSS 0 km/h
- Left Rear WSS 0 km/h
- Right Rear WSS 0 km/h
- Brake Switch
- FL Hold Solenoid Command: Off
- FL Hold Solenoid Feedback: Off
- FL Release Solenoid Command: Off
- FL Release Solenoid Feedback: Off
- FR Hold Solenoid Command: Off
- FR Hold Solenoid Feedback: Off
- FR Release Solenoid Command: Off
- FR Release Solenoid Feedback: Off
- RL Hold Solenoid Command: Off
- RL Hold Solenoid Feedback: Off
- RL Release Solenoid Command: Off
- RL Release Solenoid Feedback: Off
- RR Hold Solenoid Command: Off
- RR Hold Solenoid Feedback: Off
- RR Release Solenoid Command: Off
- RR Release Solenoid Feedback: Off
This information could not be obtained.
On Vehicle Testing Safety
Lifting and Supporting Vehicles
To safely lift and support a motor vehicle on a flat surface
Vehicle: Opel Model: Vectra
Ensure the floor surface is clean and flat: Yes
Apply the parking brake; slacken wheel nuts of wheels to be removed: Yes
Identify a safe vehicle chassis member to lift the vehicle using the jack: Yes
Lift the jack until it is touching the chassis member: Yes
Release the parking brake to allow the vehicle to roll while lifting: Yes
Recheck the location of the jack before lifting the wheels off the ground: Yes
Locate axle stands in a safe position on solid vehicle member: Yes
Have your tutor check before lowering the jack: Yes
Lower the jack slowly until the vehicle is supported by the stands: Yes
Lowering the Vehicle
Ensure all wheel nuts are located before removing vehicle stands: Yes
Lower the vehicle gently to the floor: Yes
Apply the parking brake: Yes
Torque and check wheel nut tightness: Yes
Have your tutor check the vehicle: Yes
On the vehicle that you have been assigned identify the following components to your tutor:
Wheel speed sensor: Yes
ABS control unit: Yes
ABS modulator: Yes
ABS pump motor: Yes
Parking brake switch: Yes
Brake master cylinder: Yes
Brake fluid level switch: Yes
RPM sensor: Yes
Foot brake switch: Yes
Brake booster: Yes
Main ABS control unit fuse: Yes
To safely lift and support a motor vehicle on a flat surface
Vehicle: Opel Model: Vectra
Ensure the floor surface is clean and flat: Yes
Apply the parking brake; slacken wheel nuts of wheels to be removed: Yes
Identify a safe vehicle chassis member to lift the vehicle using the jack: Yes
Lift the jack until it is touching the chassis member: Yes
Release the parking brake to allow the vehicle to roll while lifting: Yes
Recheck the location of the jack before lifting the wheels off the ground: Yes
Locate axle stands in a safe position on solid vehicle member: Yes
Have your tutor check before lowering the jack: Yes
Lower the jack slowly until the vehicle is supported by the stands: Yes
Lowering the Vehicle
Ensure all wheel nuts are located before removing vehicle stands: Yes
Lower the vehicle gently to the floor: Yes
Apply the parking brake: Yes
Torque and check wheel nut tightness: Yes
Have your tutor check the vehicle: Yes
On the vehicle that you have been assigned identify the following components to your tutor:
Wheel speed sensor: Yes
ABS control unit: Yes
ABS modulator: Yes
ABS pump motor: Yes
Parking brake switch: Yes
Brake master cylinder: Yes
Brake fluid level switch: Yes
RPM sensor: Yes
Foot brake switch: Yes
Brake booster: Yes
Main ABS control unit fuse: Yes
ABS Relays
Record the name of the relay or switch that powers up the ABS ECU:
S13
Record the name of the relay or switch that powers up the ABS Pump:
K100
Record the name of the relay or switch that sends power to the ABS HCU solenoids:
K39
Relay Wire Identification:
What is the ECU pin number for the wire that brings in the power to the ABS ECU?
25
What is the ECU pin number, or other number, for the wire that controls the relay for the ABS ECU?
1 SW RT
What is the pin number for the wire that brings in the power to the ABS Pump?
14
What is the pin number, or other number, for the wire that controls the relay for the ABS Pump?
28
Relay Waveform: Capture a waveform that shows both the control circuit change when it turns on the relay, and power switching on to power something in the ABS system.
(Use the oscilloscope with two channels to capture this pattern. You may have to carefully set the trigger to capture this.) Record the Waveform below with the time and volts per division, and explain what are you measuring.
Explain what is happening in the waveform above.
ABS Pump Relay Waveform: Capture a waveform that shows both the control circuit change when it turns on the relay, and power switching on to power the ABS Pump.
(Use the oscilloscope with two channels to capture this pattern. You may have to carefully set the trigger to capture this.) Record the Waveform below with the time and volts per division, and explain what are you measuring.
Explain what is happening in the waveform above.
Control Relay takes 0.8 seconds to turn on, then 2 seconds to turn off.
Observe what happens during the ABS Self Test when you first turn the key on. Watch the warning lights, and observe power at the wires with the oscilloscope. Then discuss what is happening in the ABS systems during the Self Test.
Orange light turns on, during this time the power circuit turns on then off twice, then the orange light turns off. Power Circuit when on switches to 12V.
Create a fault in the system by slowing down the wheel speed sensor or safely shorting out an inductive wheel speed sensor while you are applying the brakes. As you are applying the brakes, notice if the ABS pumps turns on, solenoids turn on, or if the hydraulic pressure changes in one of the brake circuits and shows up on the pressure gauge. Discuss what is happening:
Red light turns on. The two gauges on the left that are held at 150psi drop to 60psi. Two gauges on right that also are held at 150psi rise up to 180psi with the needles fluctuating violently. Pressure is almost completely cut from left side and sent to right.
Catch an oscilloscope pattern when an ABS solenoid has actuated. What is the pin and name of the solenoid? 5 GN, How did you do it?
Oscilloscope turned to chop, channel 1 is connected to green 5. Brake pedal is pressed and left side wheel slowed by applying friction. Pump turns on. Oscilloscope reacts as shown in graph. There is back EMF of 24V.
S13
Record the name of the relay or switch that powers up the ABS Pump:
K100
Record the name of the relay or switch that sends power to the ABS HCU solenoids:
K39
Relay Wire Identification:
What is the ECU pin number for the wire that brings in the power to the ABS ECU?
25
What is the ECU pin number, or other number, for the wire that controls the relay for the ABS ECU?
1 SW RT
What is the pin number for the wire that brings in the power to the ABS Pump?
14
What is the pin number, or other number, for the wire that controls the relay for the ABS Pump?
28
Relay Waveform: Capture a waveform that shows both the control circuit change when it turns on the relay, and power switching on to power something in the ABS system.
(Use the oscilloscope with two channels to capture this pattern. You may have to carefully set the trigger to capture this.) Record the Waveform below with the time and volts per division, and explain what are you measuring.
Explain what is happening in the waveform above.
ABS Pump Relay Waveform: Capture a waveform that shows both the control circuit change when it turns on the relay, and power switching on to power the ABS Pump.
(Use the oscilloscope with two channels to capture this pattern. You may have to carefully set the trigger to capture this.) Record the Waveform below with the time and volts per division, and explain what are you measuring.
Explain what is happening in the waveform above.
Control Relay takes 0.8 seconds to turn on, then 2 seconds to turn off.
Observe what happens during the ABS Self Test when you first turn the key on. Watch the warning lights, and observe power at the wires with the oscilloscope. Then discuss what is happening in the ABS systems during the Self Test.
Orange light turns on, during this time the power circuit turns on then off twice, then the orange light turns off. Power Circuit when on switches to 12V.
Create a fault in the system by slowing down the wheel speed sensor or safely shorting out an inductive wheel speed sensor while you are applying the brakes. As you are applying the brakes, notice if the ABS pumps turns on, solenoids turn on, or if the hydraulic pressure changes in one of the brake circuits and shows up on the pressure gauge. Discuss what is happening:
Red light turns on. The two gauges on the left that are held at 150psi drop to 60psi. Two gauges on right that also are held at 150psi rise up to 180psi with the needles fluctuating violently. Pressure is almost completely cut from left side and sent to right.
Catch an oscilloscope pattern when an ABS solenoid has actuated. What is the pin and name of the solenoid? 5 GN, How did you do it?
Oscilloscope turned to chop, channel 1 is connected to green 5. Brake pedal is pressed and left side wheel slowed by applying friction. Pump turns on. Oscilloscope reacts as shown in graph. There is back EMF of 24V.
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:
Magnetic i.e. Pulse Generator, Inductive.
Describe how it works:
The toothed rotor spins in accordance to wheel speed.
The wheel speed sensor picks up the distance in the teeth of the rotor.
The fluctuating distance changes the reluctance which causes the magnetic field of the wires inside the sensor to generate an AC voltage.
This signal is then sent to the ECU.
Locate an oscilloscope. Turn it on and set it up to be fully operational. What oscilloscope are you using?
Digitech Dual-Channel Oscilloscope 20 MHz QC1922.
Record a waveform for each wheel speed sensor in the boxes below. Note voltage per division and time per division for each.
Are all the waveforms exactly the same? No. Discuss what are the differences, and what can cause these differences between the waveworms:
Just mild fluctuations in voltage
With the wheels speed sensors spinning, measure AC volts with a multi-meter and record here:
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 would be more accurate in picking up things like damaged toothed rotor or or bad signal
- Left Front ECU Pin# 4 and 5 B19
- Left Rear ECU Pin# 7 and 9 B21
- Right Front ECU Pin# 11 and 21 B20
- Right Rear ECU Pin# 24 and 26 B22
Magnetic i.e. Pulse Generator, Inductive.
Describe how it works:
The toothed rotor spins in accordance to wheel speed.
The wheel speed sensor picks up the distance in the teeth of the rotor.
The fluctuating distance changes the reluctance which causes the magnetic field of the wires inside the sensor to generate an AC voltage.
This signal is then sent to the ECU.
Locate an oscilloscope. Turn it on and set it up to be fully operational. What oscilloscope are you using?
Digitech Dual-Channel Oscilloscope 20 MHz QC1922.
Record a waveform for each wheel speed sensor in the boxes below. Note voltage per division and time per division for each.
Are all the waveforms exactly the same? No. Discuss what are the differences, and what can cause these differences between the waveworms:
Just mild fluctuations in voltage
With the wheels speed sensors spinning, measure AC volts with a multi-meter and record here:
Left Front 3.5V Resistance=1.4K ohms
Left Rear 2.5V Resistance=1.43K ohms
Right Rear 5.2V Resistance=1.6K ohms
Right Front 4.4V Resistance=1.62K ohms.
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 would be more accurate in picking up things like damaged toothed rotor or or bad signal
ABS Off-Car
Anti-lock Braking Systems Lab Workbook (4825)
Off-car Exercises Think 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.
Whilst checking for connection and/or sensor faults check the ECU housing for physical damage also
Lets review the ABS system to remind ourselves what components are included and how they should work.
Name the Numbered parts in the diagram.
1. Disc Brake
2. Wheel Speed Sensor
3. Toothed Rotor
4. Electronic Control Unit
5. Brake Master Cylinder
6. Brake Caliper
7. Brake Booster
Wiring Diagram Practice
There are a number of components in the ABS Systems 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.
On the ABS wheel sensor what is the reason for the braided wire?
Identify and list all the fuses that are used by the ABS Circuit.
Identify the earths for the ABS control unit and ABS motor the wire colours and what pin numbers.
On the Wiring Diagram for the ABS Actuator, identify which solenoids control which wheel cylinder. Then note the wire colours and pin numbers.
Which of the following gives the correct condition of the inlet and outlet solenoids valves under normal braking?
Which of the following gives the correct condition of the inlet and outlet solenoids valves when the ABS is operating to reduce wheel brake pressure?
Which of the following gives the correct condition of the inlet and outlet solenoids valves when the ABS is operating to hold wheel brake pressure?
Which of the following gives the correct condition of the inlet and outlet solenoids valves when the ABS is operating to increase wheel brake pressure?
In the four cases above state when the ABS motor will be working.
There are three main types of wheel speed sensors on modern vehicles. One sends an analogue signal using an inductive pick-up, the others send a digital signal using either a hall effect or magneto-resistant encoder.
On the graph below draw a digital signal that switches 5V every 2s.
Mark V and t scales on the graph that will show the signal well.
On the graph below draw an analogue signal with a frequency of 0.5Hz and a maximum of +3 volts. Mark V and t scales on the graph that will show the signal well.
Off-car Exercises Think 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. True
- Enclosure seal damaged and with obvious sign of water ingress. True
- Obvious sign s of mechanical damage to the enclosure. True
- Faults are much more likely to be with connections or sensors. True
Whilst checking for connection and/or sensor faults check the ECU housing for physical damage also
Lets review the ABS system to remind ourselves what components are included and how they should work.Name the Numbered parts in the diagram.
1. Disc Brake
2. Wheel Speed Sensor
3. Toothed Rotor
4. Electronic Control Unit
5. Brake Master Cylinder
6. Brake Caliper
7. Brake Booster
Wiring Diagram Practice
There are a number of components in the ABS Systems 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: White Black
- Front Left: Green Red
- Rear Left: Blue Pink
- Rear Right: Yellow Brown
On the ABS wheel sensor what is the reason for the braided wire?
- To provide protection and noise reduction.
Identify and list all the fuses that are used by the ABS Circuit.
- F14 Fuse Box, 10A Gauge, 20A Dome, 15A Stop, FL Main 3.0W and 15A ECU-IG.
Identify the earths for the ABS control unit and ABS motor the wire colours and what pin numbers.
- BI, BJ and BL (all white and black) for ECU are pins 10 and 7.
- EA and EB (White and Black for both) for motor pin 6 on relay and pin 1 on actuator.
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: Pins 2B/6B, RedWhite/RedGreen
- Front Left Wheel: Pins 3B/7B, BlueRed/BlueWhite
- Rear Left Wheel: Pins 4B/8B, GreenBlack/GreenYellow
- Rear Right Wheel: Pins 1B/5B, BrownWhite/BrownRed
Which of the following gives the correct condition of the inlet and outlet solenoids valves under normal braking?
- A: Inlet valve open , Outlet valve open
Which of the following gives the correct condition of the inlet and outlet solenoids valves when the ABS is operating to reduce wheel brake pressure?
- C: Inlet valve closed , Outlet valve open
Which of the following gives the correct condition of the inlet and outlet solenoids valves when the ABS is operating to hold wheel brake pressure?
- D: Inlet valve closed , Outlet valve closed
Which of the following gives the correct condition of the inlet and outlet solenoids valves when the ABS is operating to increase wheel brake pressure?
- B: Inlet valve open , Outlet valve closed
In the four cases above state when the ABS motor will be working.
- Whilst Holding, Reducing and Increasing Wheel Brake Pressure.
There are three main types of wheel speed sensors on modern vehicles. One sends an analogue signal using an inductive pick-up, the others send a digital signal using either a hall effect or magneto-resistant encoder.
On the graph below draw a digital signal that switches 5V every 2s.
Mark V and t scales on the graph that will show the signal well.
On the graph below draw an analogue signal with a frequency of 0.5Hz and a maximum of +3 volts. Mark V and t scales on the graph that will show the signal well.
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