ABS
Off - Car Exerses
Think abuot ABS Repair:
. Spiked by caless welding, i.e MIG weldung without disconnecting the battery .True./fals.
TRUE When welding on cars there are two basic rules to follow: Always unhook the Positive and Negative cables from the battery terminals. Set a grounding clamp as close as possible to the area around you are welding with a clean connection
. Enclosure seal damaged and with obvious sign of water ingress.
TRUE. If the enclosure seal is cracked or damaged, water or other substances have a way of getting into the compartment and damaging the ECU
. Obvios signs of mechanical damage to the enclusure.
TRUE. Mechanical damage can destroy the ECU depending on what and how the damage was occurred in the first place
. Often ECU will be misdiagnosed as faulty usually because the technician is inexperinced in faultfinding. Faults much more likly to be with connection or sensor. TRUE. A chipped rotor tooth, damaged sensor or cracked or broken connection hose will send no, or false information to the ECU. Also, as the ECU has hundreds, or even thousands of processes at a time, it is much more common that a sensor or connection has become faulty rather then the ECU itself being faulty.
discuss how these ECU issues should be incorporated into diagnostic practices to test an ABS system
You culd use the scan tool and have a look to see if there a diagnostic trouble code
Using ocillocpe or muiltmeter to test all the wheel speed sensors and do all the test that needed to be. Check all the connections expecially connnections to the ECU and check wiring for damage
ABS Wiring and Operation
ABS components
1; disk
2 wheel speed sensor
3 rotor
4 HCU/ABS ECU
5 master cylender
6 calliper
7 boster
Wiring Digram Practice
Using the wiring diagram in the workshop manual identfy the wheel speed sensors and list ttheir wire colur for each sensor
Frount right A23 , Brown & yellow
Frount left : A22, Blue & Pink
Rear left : A9 , Green & Red
Rear right: A10 , Black & White
On the ABS wheel sensor what is the reason for the braded wire?
So both wires receive any interference equally and be compared to filter it out.
Identefy and all list all the fueses are used the ABS circuit?
F14, F1 main fuse, 10A gage, 20A dimo, 15A stop, 15A ECU, 15A stop
Identify the earths for the ABS control unit and ABS motor their wire colours what pins numbers
E2 the earth white & Black
On the wiring diagram for the ABS actuator, identify which solenoids control which wheel cylinder
Front right wheel : pin number 9 & 10
White & black
Frount left wheel: 23A , 22A
Grenn & red
Rear left wheel: Pin number 3B, 2B
Blue & pink
Rear right weel: pin number 8B, 9B
Yellow & Brown
Using the picture as a guide, 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
B: x Inlet valve Open Outlet valve Closed
C: ____ Inlet valve Closed Outlet valve Open
D: ____ Inlet valve Closed Outlet valve Closed
Using the picture on the next page as a guide, 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?
A:____ Inlet valve Open Outlet valve Open
B:____ Inlet valve Open Outlet valve Closed
C: x Inlet valve Closed Outlet valve Open
D: ____ Inlet valve Closed Outlet valve Closed
Using the picture as a guide, which of the following gives the correct condition of the inlet and outlet
solenoids valves when the ABS is operating to hold brake pressure?
A:____ Inlet valve Open Outlet valve Open
B:____ Inlet valve Open Outlet valve Close
C:____ Inlet valve Closed Outlet valve Open
D: x Inlet valve Closed Outlet valve Closed
Using the picture as a guide, 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?
A:____ Inlet valve Open Outlet valve Open
B: x Inlet valve Open Outlet valve Closed
C:____ Inlet valve Closed Outlet valve Open
D:____ Inlet valve Closed Outlet valve Closed
Inthese four cases when the inlet valve is closed and the outlet valve is open the ABS motor will be working, cause increase breake pressure.
There are three main types of wheel sensors on modern vehicles. One sends an analogue signal
using and inductive pick up, the others send a digital signal using ether hall effect or magnetoresistant
encoder.
On the graph below draw a digital signal that switches 5 volts every 2 seconds.
Mark volt and time scales on graph that will show the signal well.
On the graph below draw an analogue signal with a frequency of 0.5 Hz and a maximum of +3
volts. Mark volt and time scales on graph that will show the signal well
ABS Demonstrators
Locate the wiring diagram for your demonstrator vehicle. Find the ABS wheel speed sensor pinout
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 # 7and 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?
Inductive
It works by having a magnetic ring with teeth on it. As the ring spins the teeth pass by a coil, when the teeth approach he coil they induce a positive voltage and as they move away a negative voltage. The ECU uses the frequency to figure out how fast the ring is spinning and in turn how fast the wheel is spinning.
for each wheel speed sensor in the boxes below. Note voltage per division
Record a waveform
and time per division for each. Please don’t keep the ABS units on very long because it drains the
Frount lift sensor , Pin # 5
Left rear wheel speed sensor
Rear frount wheel speed sensor
Rear right wheel speed sensor
We used to oscilloscope for recording the waveform of these four wheel speed sensor the first one wich is on latop very sensitive the oscilloscope just for comperare.
The Anti-lock Braking System (ABS) relies upon information coming in from the wheel speed sensors.
If under heavy braking the ABS Electronic Control Module (ECM) loses a signal from one of the road wheels, it assumes that the wheel has locked and releases that brake momentarily until it sees the signal return. It is therefore imperative that the sensors are capable of providing a signal to the ABS ECM.
The operation of an ABS sensor is not unlike that of a crank angle sensor, using a small pick-up that is affected by the movement of a phonic wheel, moving in close proximity. The relationship between the phonic wheel and the sensor result in the production of a continuous Alternating Current (AC) ‘sine wave’ that can be monitored on an oscilloscope. The sensor, recognisable by its two electrical connections (some may have a coaxial braided outer shield) will produce an output that can be monitored and measured on the oscilloscope.
With the wheel speed sensor spinning , measure AC volts with a multi meter and record here.
Left front sensor 3.433 volts
Left rear sensor 2.542 volts
Right front sensor 4.289 volts
Right rear sensor 4.88 volts
The multi meter only find only the otput voltage of wheel speed sensor and lso we can not the ohmeter test on hall effect sensor type sensor it could be damaged the senor only we can use volt meter , but on inductive type we can use the ohmeter for internall resistance of winding.
The better test is oscilloscope .
this is not an accurate way to diagnose a wheel speed sensor as as you cant see if there are any flat spots (missing teeth) and that the waves are even(misshaped ring).
ABS Relays
Record the name of the relay or switch that powers up the ABS ECU: (look at the wiring diagram)
K39 - system relay.
Record the name of the relay or switch that powers up the ABS pump: (look at the wiring diagram)
K100 motor relay
Record the name of the relay or switch that sends power to the ABS HCU solenoids: (look at the
wiring diagram)
K38 system relay
ABS motor 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# 51
What is the ECU pin number, or other number, for the wire that controls the relay for the ABS
ECU?
Pin# 15
What is the pin number for the wire that brings in the power to the ABS Pump?
30
What is the pin number, or other number, for the wire that controls the relay for the ABS Pump?
31
Catch an oscilloscope pattern when an ABS solenoid has actuated. What is the pin and name of the solenoid? How did you do it?
I caught this pattern by slamming on the brakes at 800ms. The voltage then went up to 5v and stayed. This means the solenoid was off until I slammed onto the brakes, then the solenoid turned on, and this is how I got my reading of 5V
Relay waveform:
the relay, and the power switching on to power something in the ABS system. (Use an 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 you are measuring.
Channal # 1 is 9 volts
channal # 2 is 4 volts
Explain what is happening above.
For the relay to switch on, the control circuit needs a certain amount of voltage. When there is no power running through the control circuit, the switching circuit will be 0V. When I switched the ABS on after 200ms, the switch closed, and voltage could now go through the switch circuit. However, after 50ms, the voltage dropped to 10V for 50ms, and then raised back up to 13V. The reason for this drop was from the Pump turning on and testing itself, and then turning itself off
: Capture a waveform that shows both the control circuit change
ABS Pump Relay waveform
when it turns on the relay, and the power switching on to power the ABS Pump. (Use a 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.
Channal # 1 relay pttren , volt per division = 10 volts/ pin# 9
Channal # 2 motor pump pattren , volt per divisio = 5 volts/ pin# 11
Time ,per division= 1.00s
Arrow A is the point relay is ON
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 an oscilloscope. Then discuss what is happening in the ABS system during the Self Test.
When I turn the key on, the ABS warning lamp comes on. This is because the ABS is doing a self test. The system relay switch closes and voltage runs through to the Motor Pump Relay and Power at the pump jumps to 12V, and then after a few seconds switches off and voltage at the pump goes back to 0V. The lamp then goes off, indicating that everything is fine with the ABS.
Create A Fault in the system by slowing down a wheel speed sensor or safely shorting out an inductive wheel speed sensor while you are applying the brakes. (Don't short out a Hall Effect, or Magneto-Resistive sensor) As you are applying the brakes, notice if the ABS pump 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 below:
In order to slow down the rotor, I had to manually create friction against the rotor, but because the rotor was spinning too fast for I thought of just locking up the rotor before I turned the machine on. With pice of plastic pipe hard aginst, I turned the machine on, but noticed the pump wasn't doing a self test, so I had to slowly release the brakes until the pump could do a self test and then turn off before locking up the rotor. I quickly noted the hydraulic pressure in all 4 chambers of 1000Kpa. Then when I locked the rotor once more I noticed straight away the Pump turning on. I also noted the pressure in one of the chambers had dropped drastically but the other 3 chambers were still at 1000Kpa.
On vehicle testig:
Lifting & Supporting vehicles Student name…Moheb ghazi ……………………before lowering the jack OK ……………Scoot cheked
Scan Tool
Scan Tools are used to measure and diagnose your vehicle information, such as RPM, Ignition Timing, Injector Pulse width and readings from a number of sensors such as the 02 sensor,
TPS (throttle
positioning sensor), and (
MAF) mass airflow sensor. It will also show certain switch position signals
Using A Scan Tool
1. Plug the scan tool into the ECU, either under the dash or under the steering wheel. (Could be hidden)
2. Power On the Scan Tool. The display will come on, and after it communicates with the car's computer for a few seconds, it will display an OK message or a menu.
3. Navigate the menu to find the stored codes that the car's computer has stored into memory. These codes are collected overtime, and unless the vehicles battery has been disconnected, they should remain in memory. The scan tool will display these codes, along with basic data information about the code.
4. Write down the codes that are displayed and then research them. Automotive repair manuals will have a list of these codes and what they mean for that type of make or model. Many codes will start with a letter, followed by several numbers, such as F-233, and they are tripped by sensors that the computer monitors constantly. When these sensors determine something is wrong with the motor, they store the code in the computer so that the mechanic can determine the i
ssue and repair it.
Example.
Here is a fault code for a 6 cylinder engine.
As you can see this is a 5 digit number, with a letter at the front. When I read the manual for this type of this vehicle, or go to the following website
http://www.youfixcars.com/, I can see that the fault code is P0306- Cylinder 6 Misfire Detected. We now know that the 6
th cylinder has a fault, and can now try to work out what the actual problem is. It could be a dirty spark plug, dirty distributor or any number of things. But
at least now we know what the problem is. However the Scan Tool is preset to finding more priority faults first, so after the problem has been fixed, another isolated problem may still need to be attended to.
Using a Scan Toll
Using a scan tool go to the ABS live datata screen and not the all the sensors, data and what is telling.
1. Cont DTC mod ................ 3
2. ABS valve CTRL Relay .....ON
3. ABS warn Lamp start ..........ON
4. BAT postiv volt ...................14.75 V
5. Brake switch in .....................OFF
6. Brake warn Lamp state........ON
7. Hydralic Pump motor ...........OFF
8. L/F ABS IN valve ..............OFF
9. L/F ABS OUT valve ............OFF
10. L/F wheel speed sensor .....13KPH
11. L/R ABS IN valve ..............OFF
12. L/R ABS OUT valve ..........OFF
13. R/L Speed Sensor ..............0KPH
14. L/F wheel speed sensor......25KPH
15. L/R wheel speed sensor .....8KPH
16. ABS in valve .......................OFF
17. ABS out valve .....................OFF
In this live data i notced the L/R wheel speed sensor is faulty that shows on scan 8 KPH that is not wright signal. because that reading is on statinoray car was on jak back tires are not moving . That way the ABS warn Lamp is on.
The hydraulik pump is off because we did not press the brake pdle , and also all the ABS valve are off.
The other cause off ABS warn lamp is on the brake switch warn is on that the cause of fault of ABS warn lamp.
We can see diffrence between two front wheel speed sensors wich the left side 25KPH and the Right side is 13KPH that should be right , because in scan time we had take out only the L/F side tyer that may be unblanced . The hydraulik motor shows on scan off , because we did not press the brake padel in scantime , the pump working only when incese the pressure in hydraulic system , the ABS relay is on that means the ABS system has power . and power from 14.75 v wich is alternator power supplay .
To safely lift and support a motor vehicle on a flat surface
Ensure the floor surface is clean and flat OK
Apply the parking brake; slacken wheel nuts of wheels to be removed OK
Identify a safe vehicle chassis member to lift the vehicle using the jack OK
Lift the jack until it is touching the chassis member OK
Release the parking brake to allow the vehicle to roll while lifting OK
\recheck the location of the jack before lifting the wheels off the groundOK
Locate axle stands in a safe position on solid vehicle member OK
Have your tutor check
Lower the jack slowly until the vehicle is supported by the stands
Electronic Transmission and Scan Tolls
Note: these abbreviations are from the GM workshop manual but are fairly common for most makes and models. Describe what they mean below.
PCM: Power-Train Control Module.
The Power-Train Control Module is a combined control unit, consisting of the Engine Management ECU and the Transmission Control Unit
TCC: Torque Converter ClutchThe Torque Converter Clutch acts as the equivalent of a manual clutch. It separates the load from the power source
TPS: Throttle Position SensorThe Throttle Position Sensor or TPS is a sensor that monitors the position of the throttle in an internal combustion engine
ECT: Engine Coolant TemperatureThe Engine Coolant Temperature is a sensor that turns on the electric fan or sends a signal to the operator when the coolant reaches a temperature above it's recommended parameters
VSS: Vehicle Speed SensorDetects how fast the wheel is rotating by using a rotor tooth and sensor that sends a signal to the ECU
PSA: Transmission Range Fluid Pressure Switch AssemblyThe PSA is a sensor that detects all the shift points in the shifting of the gears in an Automatic Transmission
TTS: Transmission Temperature SensorThe TTS lets the ECU know how warm or cold the transmission fluid is and adjusts the timing of the shifts.
Use the following Holden Shift chart for questions below.
Which solenoids are "on" when this vehicle is shifted into drive and starts out in first gear?Both Solenoids are on on when this vehicle is in 1st gear.
Which solenoids are "on" when this vehicle automatically shifts into second gear?When the vehicle switches to second gear, the second solenoid is on
Which solenoids are "on" when this vehicle automatically shifts into third gear?No solenoids are on when this vehicle is in 3rd gear
Which solenoids are "on" when this vehicle automatically shifts into fourth gear?The 1st solenoid is on when this vehicle is in 4th gear
Shift solenoid mailfunction
Describe what would happen if none of these solenoids came "on". Could the vehicle drive? What gear would it be in? How fast could it go? Could it have the power to climb a hill?
If all the solenoids were off in this vehicle, the only gears this vehicle could use would be 3rd gear. That is because in 3rd gear this transmission does not need any solenoids on. The vehicle will be slow and sluggish at start off and could only use third gear. As for climbing a hill, the vehicle could drive up it if the vehicle had a running start
Codes:
Codes: Pick two transmission codes out of repair information, and describe what the code means and what mailfunction would cause the code:
Code: LR Solenoid Valve Open
Code:OD Solenoid Valve Open
Diagnosis:
For each code listed above, discuss what tests you could run to diagnose the problem.
1st problem testing:With the vehicle stuck in 3rd gear, we tryed shifting the car into a different gear. But because all the solenoid valves were stuck open and wouldn't close, the vehicle would not shift and it stayed in 3rd gear.
2nd problem testingFor the 2nd test, we plugged the solenoid cable back into the transmission and turned the car on. We were then able to change up and down gears. We then used the scan tools to make sure the valves were closing when we changed gears and they did
Ensure all wheels and nuts are located before removing vehicle stands
Lower the vehicle gently to the floor OK
Apply parking brake OK
Torque and check wheel nut tightness OK
Have your tutor check the vehicle OK
On-Car Exercises
On the vehicle that you have been assigned identify the following components to your tutor:
Wheel speed sensor
ABS control unit
ABS modulator
ABS pump motor
Parking brake switch
Brake master cylinder
Brake fluid level switch (if fitted)
RPM sensor
Foot brake switch
Brake booster
Main ABS control unit fuse
Instructor OK? ____OK , I identify all components and showed them to tutor.
ABS Wheel Speed Sensors
On the vehicle you have been assigned does it use analogue or digital wheel sensors?
Analogue
How did you conclude the wheel sensors were analogue or digital?
Because there are only 2 wires on the sensors. Digital sensors have three.
Measure the air gap for each sensor. State the air gap and visual condition of each wheel sensor.
Front Right
0.356mm. The air gap was good, the gap should be between .4 and 1mm
Front Left
0.356mm. The air gap is good. The gap is between the specifications, and there is no visual wear to the sensor
Using an oscilloscope connect it to a wheel sensor and record the pattern shown, If the sensor is a analogue sensor then just connect the probe and spin the wheel. If the sensor is digital you will need to have the ignition before you turn the wheels. (Left Image Front Wheel Sensor)
Volt/per divisio= 0.5v , Time/per division= 10ms
Is this pattern analogue or digital?
Analogue
Using the frequency scale on a multimeter. Turn the wheel approximately the same speed as in the above test. Note the frequency and compare it to the graph you drew above.
Frequency Observations
My recorded results when measuring the frequency of the wheels with a multimeter were 2.22 Hz for the front wheel sensors . Meaning the rear wheels were spinning slighty slow.
