Cruise control - the whole nine yards...........
09-27-2008, 12:00 PM
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Cruise control - the whole nine yards...........
TEST PROCEDURE FOR FACTORY FITTED CRUISE CONTROL
AUDI 100 & A6 1992-1997
(ALSO COMPATABLE WITH SOME VW MODELS)
THE FOLLOWING STEP BY STEP TESTS ARE WITHIN THE SCOPE OF ANY DIY ENTHUSIAST AND ARE CONDUCTED USING A STANDARD MULTI-TESTER
AN ASSISTANT IS USEFUL - GET THE WIFE OR GIRLFRIEND INVOLVED.
Where is it?
The control unit is mounted behind the Glove compartment on the back of the wheel arch with two 10mm nuts.
It is a silver box a little bigger than a 20 cigarette pack and is marked
"GR Steuergerät 12V".
Wiring colour codes are shown in brackets in the test procedure. e.g. (ws/bl)
They are as follows:-
bl = blue
br = brown
ge = yellow
gn = green
gr = grey
li = purple
ro = red
sw = black
ws = white
There may be differences for some models, especially with Volkswagen. Please refer to your wiring diagram.
Since the tests below are conducted with the Cruise Control unit disconnected there is no risk of damage to the Cruise Control computer unit.
__________________________________________________ ______________________
TEST SEQUENCE
ALL THE FOLLOWING TESTS ARE CONDUCTED ON THE CRUISE CONTROL CONNECTOR PLUG. THE CONNECTION NUMBERS ARE PRINTED ON THE CRUISE CONTROL COMPUTER.
Please ignore the 4 pin black connector plug which is connected into the back of the brown control box connector on some models. This is for use with the Audi/VAG tester.
The brown 12 pin connector must be removed from the Cruise Control computer to perform the tests.
NB. Be extremely careful not to touch a live wire to connection 9 (ws/bl) on the plug. This pin carries the signal from the speedometer and a short circuit may cause some damage.
Check fuses 9, 14, and 20 before continuing.
Power Supply
1a) Manual transmission only.
Connect a volt meter between contact 8 (sw/ws) and contact 5 (br).
Turn the ignition switch on.
Move the slide switch on the stalk to "ON"
Result reading should be battery voltage.
If there is no reading check the wiring from fuse# 14. Check the stalk switch.
1b) Automatic transmission only.
Connect a volt meter to contact 8 (sw/ws) and contact 5 (br).
The vehicle must be driven above 35 km/h to conduct this part of the test.
Result reading should be battery voltage.
If there is no reading, check wiring, fuse#20 and have TCM tested for faults.
A quick test to establish whether or not you are getting power from the TCM is to connect a thin wire to fuse# 20 in the fuse panel by jamming it in with the fuse and connect it to earth via a test lamp or volt meter. Drive the car above 35km/h and if the TCM is sending current the test light will illuminate or the voltmeter will show a battery voltage reading. (Note: - some diesel versions use a different fuse)
Note - Automatic transmission: For 096 and 097 transmissions with a 38 pin connector at the TCM, the power comes from pin 38 on the TCM via fuse# 20 in the fuse panel.
For 01# series automatic transmissions. These normally have a 68 pin connector at the TCM. There are quite a few variations in the wiring between the Cruise Control and TCM depending on the combination of engine and gearbox type used.
The power could come from connection 24, 54 or 61 on the TCM via fuse# 20 in the fuse panel. Diesel models may differ.
You will have to refer to your wiring diagrams to verify these connections.
The TCM performs two checks before sending current to the Cruise Control. It establishes that the vehicle speed is above 35km/h and that the gear selector is in D, 3 or 2. The Cruise control will not be powered up with the gear selector in P, N or 1. This involves the multifunction switch.
I have not attempted to offer any reasons for the TCM failing to send current to the Cruise Control unit. This requires further investigation and thorough testing of the TCM.
I have however found a method of bypassing the TCM in order to get the Cruise Control to operate.
Note: - Even if there is an apparent fault at this point the rest of the tests below can still be carried out.
Switch Testing
Stalk switch:- (Ignition off)
1) With the stalk switch in the on position. Connect ohmmeter to contact 8 (sw/ws) and contact 10 (bl)
Slide stalk switch to "Res" position.
Result should be 0 Ohm
If there is a reading check for short circuits in wiring or stalk switch.
2) With the stalk switch in the on position. Connect the ohmmeter to contact 8 (sw/ws) and contact 4 (ro/gn).
Press the "Fix/Set" button.
Result should be 0 Ohm
If there is a reading check for short circuits in the wiring or stalk switch.
Brake switch:-
1a.) Connect ohmmeter to contact 11 (sw/ro) or (sw/ge) and contact 5 (br).
Move the stalk switch to ON.
Result should be 0 Ohm. This means that the switch at the brake pedal is closed. This is correct.
If there is a reading the switch at the brake pedal is open. Check switch for correct adjustment and functionality. Check connections. The brake pedal could be binding and not always returning to its stop. This can happen when you have lightly touched the pedal without actually pressing it down. Lubricate as may be necessary.
1b.) Leave the Ohmmeter connected as above and press brake pedal
Reading should be infinite ohms.
Depending on how the brake light switch is adjusted you may get a voltage before the circuit is broken when pressing the brake pedal. This is normal and means that the brake light switch is closing before the cruise control brake switch is opening. (See electrical diagram for details)
If result is 0 Ohm - check the switch at the brake pedal for correct adjustment and functionality. Check the wiring connections at the brake pedal switch.
(For manual transmission the clutch switch is also connected to contact 11 (sw/ro) and should be tested as above)
Vacuum pump test.
1) Automatic transmission - Connect contact 7 (bl/ro) to a convenient live connection in one of the nearby plugs. Most of the connections here are only live when the ignition switch on. Manual transmission - bridge contact 7 and 8 together.
(Tip: When making temporary live connections us a length of wire fitted with an inline fuse. This will prevent short circuits and subsequent damage to the electrical system should you connect to the wrong terminal)
Connect contact 6 to earth.
Switch ignition on (no need to start the engine) - the vacuum pump should run.
2) Leave the bridge to contact 7 connected and remove the connection from contact 6.
Take a connection from contact 12 (gn/bl), switch the ignition on, (no need to start the engine) and briefly tap to earth.
There should be a click from the pump meaning that the vacuum pump relief valve is operational.
If the above test results are satisfactory then proceed as follows:-
3) Leave the bridge to contact 7 connected.
Connect contact 6 (bl/ws) to earth.
Take a connection from contact 12 (gn/bl), switch the ignition on, (Do not start the engine!) and hold the connection from contact 12 (gn/bl) to earth. The vacuum diaphragm should pull the throttle open fully - this will determine if there are any vacuum leaks and that the brake switch vacuum relief valve is functioning correctly. (Also clutch switch where applicable)
If all of the above tests are passed then the Cruise Control unit possibly needs attention. This is rare. The unit is incredibly simplistic and unless dropped or shorted out it should not malfunction.
Should it be faulty it is easily opened and in most cases a good electronics technician can repair it. I believe that if an electronic component has not been fried then it can be repaired.
Notes:
The most common Cruise Control fault is with the brake, and where applicable, the clutch switches. The correct fitting and adjustment of these switches is therefore very important. Full details can be found in your workshop manual.
The stalk switch is known to fail. The flimsy internal contacts wear out fairly easily.
Due to the fact that the control unit is enclosed behind the glove compartment there is a possibility of dampness and corrosion forming on the connectors. Simply disconnecting, cleaning and reconnecting the connectors may solve many problems.
AUDI 100 & A6 1992-1997
(ALSO COMPATABLE WITH SOME VW MODELS)
THE FOLLOWING STEP BY STEP TESTS ARE WITHIN THE SCOPE OF ANY DIY ENTHUSIAST AND ARE CONDUCTED USING A STANDARD MULTI-TESTER
AN ASSISTANT IS USEFUL - GET THE WIFE OR GIRLFRIEND INVOLVED.
Where is it?
The control unit is mounted behind the Glove compartment on the back of the wheel arch with two 10mm nuts.
It is a silver box a little bigger than a 20 cigarette pack and is marked
"GR Steuergerät 12V".
Wiring colour codes are shown in brackets in the test procedure. e.g. (ws/bl)
They are as follows:-
bl = blue
br = brown
ge = yellow
gn = green
gr = grey
li = purple
ro = red
sw = black
ws = white
There may be differences for some models, especially with Volkswagen. Please refer to your wiring diagram.
Since the tests below are conducted with the Cruise Control unit disconnected there is no risk of damage to the Cruise Control computer unit.
__________________________________________________ ______________________
TEST SEQUENCE
ALL THE FOLLOWING TESTS ARE CONDUCTED ON THE CRUISE CONTROL CONNECTOR PLUG. THE CONNECTION NUMBERS ARE PRINTED ON THE CRUISE CONTROL COMPUTER.
Please ignore the 4 pin black connector plug which is connected into the back of the brown control box connector on some models. This is for use with the Audi/VAG tester.
The brown 12 pin connector must be removed from the Cruise Control computer to perform the tests.
NB. Be extremely careful not to touch a live wire to connection 9 (ws/bl) on the plug. This pin carries the signal from the speedometer and a short circuit may cause some damage.
Check fuses 9, 14, and 20 before continuing.
Power Supply
1a) Manual transmission only.
Connect a volt meter between contact 8 (sw/ws) and contact 5 (br).
Turn the ignition switch on.
Move the slide switch on the stalk to "ON"
Result reading should be battery voltage.
If there is no reading check the wiring from fuse# 14. Check the stalk switch.
1b) Automatic transmission only.
Connect a volt meter to contact 8 (sw/ws) and contact 5 (br).
The vehicle must be driven above 35 km/h to conduct this part of the test.
Result reading should be battery voltage.
If there is no reading, check wiring, fuse#20 and have TCM tested for faults.
A quick test to establish whether or not you are getting power from the TCM is to connect a thin wire to fuse# 20 in the fuse panel by jamming it in with the fuse and connect it to earth via a test lamp or volt meter. Drive the car above 35km/h and if the TCM is sending current the test light will illuminate or the voltmeter will show a battery voltage reading. (Note: - some diesel versions use a different fuse)
Note - Automatic transmission: For 096 and 097 transmissions with a 38 pin connector at the TCM, the power comes from pin 38 on the TCM via fuse# 20 in the fuse panel.
For 01# series automatic transmissions. These normally have a 68 pin connector at the TCM. There are quite a few variations in the wiring between the Cruise Control and TCM depending on the combination of engine and gearbox type used.
The power could come from connection 24, 54 or 61 on the TCM via fuse# 20 in the fuse panel. Diesel models may differ.
You will have to refer to your wiring diagrams to verify these connections.
The TCM performs two checks before sending current to the Cruise Control. It establishes that the vehicle speed is above 35km/h and that the gear selector is in D, 3 or 2. The Cruise control will not be powered up with the gear selector in P, N or 1. This involves the multifunction switch.
I have not attempted to offer any reasons for the TCM failing to send current to the Cruise Control unit. This requires further investigation and thorough testing of the TCM.
I have however found a method of bypassing the TCM in order to get the Cruise Control to operate.
Note: - Even if there is an apparent fault at this point the rest of the tests below can still be carried out.
Switch Testing
Stalk switch:- (Ignition off)
1) With the stalk switch in the on position. Connect ohmmeter to contact 8 (sw/ws) and contact 10 (bl)
Slide stalk switch to "Res" position.
Result should be 0 Ohm
If there is a reading check for short circuits in wiring or stalk switch.
2) With the stalk switch in the on position. Connect the ohmmeter to contact 8 (sw/ws) and contact 4 (ro/gn).
Press the "Fix/Set" button.
Result should be 0 Ohm
If there is a reading check for short circuits in the wiring or stalk switch.
Brake switch:-
1a.) Connect ohmmeter to contact 11 (sw/ro) or (sw/ge) and contact 5 (br).
Move the stalk switch to ON.
Result should be 0 Ohm. This means that the switch at the brake pedal is closed. This is correct.
If there is a reading the switch at the brake pedal is open. Check switch for correct adjustment and functionality. Check connections. The brake pedal could be binding and not always returning to its stop. This can happen when you have lightly touched the pedal without actually pressing it down. Lubricate as may be necessary.
1b.) Leave the Ohmmeter connected as above and press brake pedal
Reading should be infinite ohms.
Depending on how the brake light switch is adjusted you may get a voltage before the circuit is broken when pressing the brake pedal. This is normal and means that the brake light switch is closing before the cruise control brake switch is opening. (See electrical diagram for details)
If result is 0 Ohm - check the switch at the brake pedal for correct adjustment and functionality. Check the wiring connections at the brake pedal switch.
(For manual transmission the clutch switch is also connected to contact 11 (sw/ro) and should be tested as above)
Vacuum pump test.
1) Automatic transmission - Connect contact 7 (bl/ro) to a convenient live connection in one of the nearby plugs. Most of the connections here are only live when the ignition switch on. Manual transmission - bridge contact 7 and 8 together.
(Tip: When making temporary live connections us a length of wire fitted with an inline fuse. This will prevent short circuits and subsequent damage to the electrical system should you connect to the wrong terminal)
Connect contact 6 to earth.
Switch ignition on (no need to start the engine) - the vacuum pump should run.
2) Leave the bridge to contact 7 connected and remove the connection from contact 6.
Take a connection from contact 12 (gn/bl), switch the ignition on, (no need to start the engine) and briefly tap to earth.
There should be a click from the pump meaning that the vacuum pump relief valve is operational.
If the above test results are satisfactory then proceed as follows:-
3) Leave the bridge to contact 7 connected.
Connect contact 6 (bl/ws) to earth.
Take a connection from contact 12 (gn/bl), switch the ignition on, (Do not start the engine!) and hold the connection from contact 12 (gn/bl) to earth. The vacuum diaphragm should pull the throttle open fully - this will determine if there are any vacuum leaks and that the brake switch vacuum relief valve is functioning correctly. (Also clutch switch where applicable)
If all of the above tests are passed then the Cruise Control unit possibly needs attention. This is rare. The unit is incredibly simplistic and unless dropped or shorted out it should not malfunction.
Should it be faulty it is easily opened and in most cases a good electronics technician can repair it. I believe that if an electronic component has not been fried then it can be repaired.
Notes:
The most common Cruise Control fault is with the brake, and where applicable, the clutch switches. The correct fitting and adjustment of these switches is therefore very important. Full details can be found in your workshop manual.
The stalk switch is known to fail. The flimsy internal contacts wear out fairly easily.
Due to the fact that the control unit is enclosed behind the glove compartment there is a possibility of dampness and corrosion forming on the connectors. Simply disconnecting, cleaning and reconnecting the connectors may solve many problems.
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