TCM location

[fla 9]

Chaps

Just need to know the position of the TCM for the C - its not under the back seats as I had them out to remove teh carpet. I believe its under the dash? What does it look like (pic would be useful, but a description would also suffice) as I need to check it for loose connections. Its a 94 VR (Mike VR6 can you remember anything about this?)

 

TIA

[RW1 0]

TCM lives in the base (cavity) of the driver's door pillar/frame behind the kick panel. Same equivalent position as the brake ABS controller in the passenger side.

[Roger Blassberg 0]

er, TCM???

 

Best wishes

 

RB

[Supercharged 2]

Transmission Control Unit - maybe we should add this one to the list...

[Roger Blassberg 0]

Is it something to do with automatic transmission?

 

Best wishes

 

RB

[Supercharged 2]

Yep sorry, Auto only Roger...

[fla 9]

RW1, thanks bud, will have a little look tonight see if i can find that damn loose connection "short to ground". Have you had this some up at all in a scan? If so what did you do? I'm gonna check the earths from the battery to the g/box and engine bulkhead, maybe give them a clean and then remove and clean the TCM connector. Would welcome any other advice.

[RW1 0]

Fla,

 

Give me the DTC fault code and I'll see what the code links to for checks.

[fla 9]

RW1, The codes were:

 

00518 - Throttle Position Sensor (G69)

16-10 - Signal Outside Specifications - Intermittent

00638 - Engine/Transmission Electrical Connection 2

03-10 - No Signal - Intermittent

00300 - Transmission Fluid Temp. Sensor (G93)

34-10 - No Elaboration Available - Intermittent

 

I dont think theres anything the matter with the TPS - just fitted recently and run the car about 50 miles with it (mainly because its been off the road for several months as I havent had the time to have a better look at it). But that 00638 is a real pain and I'm not sure how to proceed with it. I'll be changing the tranny fluid next week hopefully although its only done 50k.

TIA

[RW1 0]

OK,

 

TPS fault code 00518 does need to be fixed. In an automatic box Corrado, this signal from the throttle is also used by the Autobox TCM (ECU). So it will influence how the autobox TCM makes decisions to change gear.

 

The things to do here are first to clear the fault code and see if it returns as installing the new one my have led to this being triggered but is now not a fault condition. If that has already been done and these faults are reappearing, then look at the following:

 

Check the Throttle Position Sensor fault code 00518 by looking for an open circuit wire connection or grounding of any of the wires.

 

The autobox 00638 code is pointing to a small temperature sensor built into the circuit film strip as part of the autobox valve block. Looks like a small resistor. It isn’t a spares item from VAG. The repair is through the replacement of the whole valve block unless you find an autobox specialist who may be able do something in the workshop.

 

First thing to check is the 10 way connector on the rear lower side of the autobox which connects the valve block control film strip circuit to the car’s wiring loom.

 

Also check the circuit film for damage to the circuit tracks. This is a circuit film strip embedded in one side of the valve block (partly visible) inside the autobox above the boxes’s sump pan (best left until all else is checked and you drain the ATF oil).

 

Next check the oil temp sender by going into the VAG-COM and selecting Auto Trans 02, Measuring Blocks. Enter in one of the Groups fields "005". With the car stationary and engine running at idle and warmed up, check the autobox oil temp in field 1 (most left box) of the four fields is between 50 & 70’C (sensor field only starts reading above 40’C). If not reading or the temperature range reading cannot be achieved, then either the wiring is suspect from/in the car loom or the temp sensor G93 on the valve block circuit film is duff.

 

Also check fuses 14, 16 & 21 are OK and each has 12 volts when the car has started.

 

Check for loose earth wire connections on the earth points around the fuse relay plate area on the bodywork.

 

NB. It the battery has been disconnected, then the autobox needs to be taken through “Basic Settings” otherwise autobox gear changes can and usually behave erratically.

[fla 9]

RW1, thanks very much for the details and i must sya very comprehensive judging by the time you posted it 1.19am! OK, i've got a few questions on these pints:

1. where is the

circuit film strip as part of the autobox valve block

? Does this refer to the long black connector sitting on top of the gearbox next to the round diagnostics port?

2. How do i go through "Basic Settings" on the tranny? Is this where you turn the ignition to on without firing the engine, press and hold the throttle on the floor for about 20secs and then release and start the engine?

I mentioned in a previous thread about the slight wheeze as it shifts from 3rd to 4th, so maybe this can be resolved by the Basic Settings procedure?

 

Again, many thanks for the assistance.

[RW1 0]

Fla.

 

1a. “This is a circuit film strip embedded in one side of the valve block (partly visible) inside the autobox above the boxes’s sump pan (best left until all else is checked and you drain the ATF oil).”

 

On the underside of the autobox there is a broad shallow & flat sump pan. Obviously the Autobox is drained of ATF. The pan is held on by 4 bolts (the sump gasket will need to be renewed). When the pan is removed, this will reveal another pan plate (screen), the autobox’s valve block sitting inside behind this on the underside of the boxes’s innards and occupying an area almost as big as the sump pan’s breadth & length. Yet another replaceable gasket when the plate comes off. To the outer side of the valve block ie. the nearside wheel & parallel to it. There should be visible a narrow circuit film strip like the the film strips on the back of some instrument clusters such as the early Golfs and the Scirocco Mk2. About half way along the film strip part that is embedded into the valve block (not half way along the whole strip inside the box) but still partly visible is the temperature sensor. It looks like a resistor and is directly attached to the film strip. The film strip will run off the valve block to the sealed plug assembly in the autobox sidewall and hence onto the car’s wiring loom. The loom connection should be visible on the under side the autobox.

 

I think you should only try to get into this part of the autobox only if the sensor has failed to give a reading using VAG-COM measuring blocks screen as per the previous note.

 

Gasket Part No – Sump pan This is either 095 321 370 or 371 depending on the car.

Gasket Part No – pan plate This is 095 325 443A

 

1b. Top side connectors are not involved.

 

2. Right thoughts, actuals slightly different. With ignition on, engine not started. Select the Auto Trans 02. Select 04 Basic Settings. Key 000 in display group. Press the acclerator to the kick-down position and hold for 3 seconds. Release the accelerator and exit VAG-COM neatly all the way out to the start screen. I have my doubts about this being the solution to the wheeze, that could be the valve block sequencing.

[fla 9]

There should be visible a narrow circuit film strip like the the film strips on the back of some instrument clusters such as the early Golfs and the Scirocco Mk2. About half way along the film strip part that is embedded into the valve block (not half way along the whole strip inside the box) but still partly visible is the temperature sensor

RW1, you wouldnt by chnace have a picture of this? Advice very much appreciated.

[RW1 0]

ATF Fluid with Camera - ! No it's been a long since I saw the inside of one of these boxes.

 

I've attached a diagram to help you based on the late Golf Mk3 Autobox which is very similar.

 

I hope you have exhausted all other avenues before getting physical with the innards.

[fla 9]

Well RW1, its not running at the moment (not for the past several months in fact), but as I'm planning a gearbox swop in the summer I just want to change the tranny fluid and bring it to as normal a state as possible. Also if i can identify that the problem is only this strip I'll either do it or point it out to the person that buys the tranny. Its only done 50k miles so will prob be more useful to someone else. TBH I couldnt make much sense of the birdsnest by the tcm so decided to leave it alone - electrics are not my favourite area! In fact electrics and gearboxes!