93 Audi 100 quattro auto transmission problem
01-25-2010, 04:45 PM
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93 Audi 100 quattro auto transmission problem
I am a new Audi owner and have not had a lot to do with Audi's before.
I have encountered a problem that is replicatable EVERY time I drive the car now making it undriveable.
The vehicle is an Audi 100 Quattro 2.8L V6
It starts fine and sets off fine but as soon as some speed is reached (around 2500 rpm or around 15 mph) the entire range of transmission lights P through to 1 all light up and stay on. The car loses drive entirely and accelerating just causes the car to rev. I can stop the car turn off the ignition, start the car and set off again as if nothing has gone wrong until around 15 mph.... you get the idea.
I had the car hooked up to a diagnostic computer and was told that the "transmission range controller was outside normal tolerances" - I was told I needed a new TCU. I found and imported one of those and after it arrived (finally) you can imagine my dismay when the problem is still there!!!
Where to know? Any help appreciated. Thanks
I have encountered a problem that is replicatable EVERY time I drive the car now making it undriveable.
The vehicle is an Audi 100 Quattro 2.8L V6
It starts fine and sets off fine but as soon as some speed is reached (around 2500 rpm or around 15 mph) the entire range of transmission lights P through to 1 all light up and stay on. The car loses drive entirely and accelerating just causes the car to rev. I can stop the car turn off the ignition, start the car and set off again as if nothing has gone wrong until around 15 mph.... you get the idea.
I had the car hooked up to a diagnostic computer and was told that the "transmission range controller was outside normal tolerances" - I was told I needed a new TCU. I found and imported one of those and after it arrived (finally) you can imagine my dismay when the problem is still there!!!
Where to know? Any help appreciated. Thanks
01-25-2010, 06:48 PM
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Have you checked the wiring between the ECM and the transmission using an ohm meter? Sometimes the terminals may be coroded or damaged. Have you checked the transmission range switch and it's terminals?
02-21-2010, 11:56 AM
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Definately when shifting into 3rd gear everytime - No noise or graunching so it have to be electrical/sensor doesn't it?
02-21-2010, 12:20 PM
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more than likely it is the trans range control switch located on the side of the transmission...it located on the left side of the transmission where the shifter cable goes to the shifter lever. This switch tells the computer which gear you have selected and if it goes bad you wont have certian gears...just as you have described.
04-11-2010, 12:10 PM
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Hi - No I haven't resolved it - I would appreciate your knowledge and experience. What happened with yours? Thanks
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04-13-2010, 08:17 AM
#8
Auto transmission problem .. and fix.
The auto transmission-related problem on my 1992 100CS quattro wagon started when the car went into limp mode (2nd gear) and all the gear indicator lights on the instrument panel lit up. Engaging reverse would sometimes work, but more often fail. I looked up my Bentley manual, which says that if all the indicator lights are on, the computer most likely is functioning properly. I also read the DTC with VAG-COM, which pointed to a problem with the transmission range switch. You all probably know this, but the transmission range switch on this car is purely electro-mechanical (no electronic components), and what it does is to provide a three bit signal to the transmission computer about the position (1, 2, 3, D or R) of the gear lever,
so that (for the forward gears) the computer knows not to exceed the ratio chosen by the driver (e.g, if you put the lever in 3 the computer will only allow gears 1, 2, and 3).
One thing I noticed and I thought was significant was that my back-up lights were always on, regardless of the position of the gear lever, as if I had engaged reverse. By looking at the wiring diagrams, I saw that the circuit that supplies these lights is also controlled by the transmission range switch, so I was pretty sure that this was the culprit. As you may know this baby sits on top of the front part of the transmission. To gain access to it you have to remove the front left transmission mount, after you support the engine-transmission. I did that by fashioning an engine support out of a length of 2x4 wood beams and strong wire rope. To be safe, I also supported the left part of the transmission with a bottle jack. The switch has an electrical connection to the transmission computer and a mechanical cable connection to the gear lever. The electrical connection to the transmission valve body is also routed nearby, so this has to be undone as well. Undoing the electrical connections is straight-forward. When you are ready to disengage the cable connection to the lever, make sure the lever is in P, and note the position of the lever on the switch for when you re-install it. It has to be the same position, otherwise the wrong signal about the position of the gear lever will be transmitted to the computer.
The trickiest part was to unscrew the three screws that fasten the switch to the transmission. One has to feel these screws because they are hidden by other parts nearby, and even a mirror sight will not reveal the position of one of the three. To make things trickier, the screws do NOT have a hex head (as I thought) but are female Torx screws. To undo them (after I had stripped one), I bought the right size Torx bit (T20, I believe, but do not take my word for it) with a small bit ratchet. There is very little clearance in there, so you need a low profile wrench.
Before I got the switch out, I was resigned to paying the stealer $600 (?!) or so for a new switch. I had a (well-deserved, after all this work) pleasant surprise, when I finally saw the switch. It is a clam-shell design, with rivets securing the two pieces together. Inside there is a spring-loaded disk with grooves. Depending on the position of the disk, the grooves press or release the contacts that provide the signal to the computer and power to the back-up lights. What happened to my switch was that all the rivets had been slowly corroded, and when the last one finally popped, the clam-shell opened slightly allowing all the electrical contacts inside to go the closed position, hence the confusion of the computer and the continuous power to the back-up lights. The fix was easy after that. I cleaned and lubricated the inside of the switch, drilled out the broken rivets and replaced them with small galvanised screws and nuts (no more than 2mm screw diameter, or M2). The thing is now as good as new, and ready for another 18 years of operation, or at least until I replace the auto with a real transmission on this car (sorry slush-box fans, stick is the way for me). This is one of my future projects.
I hope this helps.
02-25-2011, 12:02 PM
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1994 Audi 1CQA Tranny issues
Well I am reading this almost a year later and am SO glad I came across your post. This is EXACTLY the issue with my Avant. Thanks ncoupe.
Sorry for not responding earlier. I took a few days off and did not follow the thread.
The auto transmission-related problem on my 1992 100CS quattro wagon started when the car went into limp mode (2nd gear) and all the gear indicator lights on the instrument panel lit up. Engaging reverse would sometimes work, but more often fail. I looked up my Bentley manual, which says that if all the indicator lights are on, the computer most likely is functioning properly. I also read the DTC with VAG-COM, which pointed to a problem with the transmission range switch. You all probably know this, but the transmission range switch on this car is purely electro-mechanical (no electronic components), and what it does is to provide a three bit signal to the transmission computer about the position (1, 2, 3, D or R) of the gear lever,
so that (for the forward gears) the computer knows not to exceed the ratio chosen by the driver (e.g, if you put the lever in 3 the computer will only allow gears 1, 2, and 3).
One thing I noticed and I thought was significant was that my back-up lights were always on, regardless of the position of the gear lever, as if I had engaged reverse. By looking at the wiring diagrams, I saw that the circuit that supplies these lights is also controlled by the transmission range switch, so I was pretty sure that this was the culprit. As you may know this baby sits on top of the front part of the transmission. To gain access to it you have to remove the front left transmission mount, after you support the engine-transmission. I did that by fashioning an engine support out of a length of 2x4 wood beams and strong wire rope. To be safe, I also supported the left part of the transmission with a bottle jack. The switch has an electrical connection to the transmission computer and a mechanical cable connection to the gear lever. The electrical connection to the transmission valve body is also routed nearby, so this has to be undone as well. Undoing the electrical connections is straight-forward. When you are ready to disengage the cable connection to the lever, make sure the lever is in P, and note the position of the lever on the switch for when you re-install it. It has to be the same position, otherwise the wrong signal about the position of the gear lever will be transmitted to the computer.
The trickiest part was to unscrew the three screws that fasten the switch to the transmission. One has to feel these screws because they are hidden by other parts nearby, and even a mirror sight will not reveal the position of one of the three. To make things trickier, the screws do NOT have a hex head (as I thought) but are female Torx screws. To undo them (after I had stripped one), I bought the right size Torx bit (T20, I believe, but do not take my word for it) with a small bit ratchet. There is very little clearance in there, so you need a low profile wrench.
Before I got the switch out, I was resigned to paying the stealer $600 (?!) or so for a new switch. I had a (well-deserved, after all this work) pleasant surprise, when I finally saw the switch. It is a clam-shell design, with rivets securing the two pieces together. Inside there is a spring-loaded disk with grooves. Depending on the position of the disk, the grooves press or release the contacts that provide the signal to the computer and power to the back-up lights. What happened to my switch was that all the rivets had been slowly corroded, and when the last one finally popped, the clam-shell opened slightly allowing all the electrical contacts inside to go the closed position, hence the confusion of the computer and the continuous power to the back-up lights. The fix was easy after that. I cleaned and lubricated the inside of the switch, drilled out the broken rivets and replaced them with small galvanised screws and nuts (no more than 2mm screw diameter, or M2). The thing is now as good as new, and ready for another 18 years of operation, or at least until I replace the auto with a real transmission on this car (sorry slush-box fans, stick is the way for me). This is one of my future projects.
I hope this helps.
The auto transmission-related problem on my 1992 100CS quattro wagon started when the car went into limp mode (2nd gear) and all the gear indicator lights on the instrument panel lit up. Engaging reverse would sometimes work, but more often fail. I looked up my Bentley manual, which says that if all the indicator lights are on, the computer most likely is functioning properly. I also read the DTC with VAG-COM, which pointed to a problem with the transmission range switch. You all probably know this, but the transmission range switch on this car is purely electro-mechanical (no electronic components), and what it does is to provide a three bit signal to the transmission computer about the position (1, 2, 3, D or R) of the gear lever,
so that (for the forward gears) the computer knows not to exceed the ratio chosen by the driver (e.g, if you put the lever in 3 the computer will only allow gears 1, 2, and 3).
One thing I noticed and I thought was significant was that my back-up lights were always on, regardless of the position of the gear lever, as if I had engaged reverse. By looking at the wiring diagrams, I saw that the circuit that supplies these lights is also controlled by the transmission range switch, so I was pretty sure that this was the culprit. As you may know this baby sits on top of the front part of the transmission. To gain access to it you have to remove the front left transmission mount, after you support the engine-transmission. I did that by fashioning an engine support out of a length of 2x4 wood beams and strong wire rope. To be safe, I also supported the left part of the transmission with a bottle jack. The switch has an electrical connection to the transmission computer and a mechanical cable connection to the gear lever. The electrical connection to the transmission valve body is also routed nearby, so this has to be undone as well. Undoing the electrical connections is straight-forward. When you are ready to disengage the cable connection to the lever, make sure the lever is in P, and note the position of the lever on the switch for when you re-install it. It has to be the same position, otherwise the wrong signal about the position of the gear lever will be transmitted to the computer.
The trickiest part was to unscrew the three screws that fasten the switch to the transmission. One has to feel these screws because they are hidden by other parts nearby, and even a mirror sight will not reveal the position of one of the three. To make things trickier, the screws do NOT have a hex head (as I thought) but are female Torx screws. To undo them (after I had stripped one), I bought the right size Torx bit (T20, I believe, but do not take my word for it) with a small bit ratchet. There is very little clearance in there, so you need a low profile wrench.
Before I got the switch out, I was resigned to paying the stealer $600 (?!) or so for a new switch. I had a (well-deserved, after all this work) pleasant surprise, when I finally saw the switch. It is a clam-shell design, with rivets securing the two pieces together. Inside there is a spring-loaded disk with grooves. Depending on the position of the disk, the grooves press or release the contacts that provide the signal to the computer and power to the back-up lights. What happened to my switch was that all the rivets had been slowly corroded, and when the last one finally popped, the clam-shell opened slightly allowing all the electrical contacts inside to go the closed position, hence the confusion of the computer and the continuous power to the back-up lights. The fix was easy after that. I cleaned and lubricated the inside of the switch, drilled out the broken rivets and replaced them with small galvanised screws and nuts (no more than 2mm screw diameter, or M2). The thing is now as good as new, and ready for another 18 years of operation, or at least until I replace the auto with a real transmission on this car (sorry slush-box fans, stick is the way for me). This is one of my future projects.
I hope this helps.
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