Unable to communicate with engine or transmission over OBD?

[Sphengali]

Originally Posted by amacman

best to leave the car indoors with the lid off the box for as long as is practical to allow any moisture to evaporate .
don`t be tempted to use excessive heat to assist drying .
the pins will require thorough cleaning and their sockets cleaned . also if you can close the sockets a bit more to have a tight grip on the pins .

I've spent quite a lot of time cleaning it up, and it worked for about 15 minutes, but then went back to TFS mode. Any suggestions for how to clean the connectors, I very thin pipecleaner but more abrasive would be great, but haven't seen anything on the market, but perhaps I don't know where to look.

Also - one of the pins is quite wobbly, I'm concerned that it's a bad connection no matter what I do - any ideas on how to fix a bad pin? If someone has a pin-out diagram, at least I could determine what the bad one does, it could just be a ground and not be 'essential' to the operation.

[Sphengali]

Something else I discovered that's a "big deal" - I cracked open the case on the TCM, and there was a LOT of corrosion on the circuit board, between the pins on the various chips - this is as important to remove or more than what builds up on the pins and connectors. I'm about to pull the ECM and do the same to it, I bet it will be bad too.

[m5james]

Sounds like a can or two of Radio Shack electronics parts cleaner and some dielectic grease might be in order.

[Sphengali]

Took the TCM apart, there was a lot of corrosion on the inside too, all that has now been cleaned up - but still the FSP message continues. I've even taken the ECM apart, it was clean however. I'm a bit stumped, wish I had a TCM to try rather than buying one outright, as there may be another problem.

[Sphengali]

I cracked open the TCM, and cleaned it out inside - it also had corrosion there. Reverse now works, and when I first start out, the tranny goes back to normal - but soon enough TFP returns... so now I'm a bit stumped. It does start to stutter around 60 km/h, and after 5 sec or so of that, once I slow down - then TFP turns on and I'm back to 3rd gear only. I need to get the OBD read again, me thinks - I hope there's something to go by... any thoughts, anyone??

[Sphengali]

I cracked open the TCM, and cleaned it out inside - it also had corrosion there. Reverse now works, and when I first start out, the tranny goes back to normal - but soon enough TFP returns... so now I'm a bit stumped. It does start to stutter around 60 km/h, and after 5 sec or so of that, once I slow down - then TFP turns on and I'm back to 3rd gear only. I need to get the OBD read again, me thinks - I hope there's something to go by... any thoughts, anyone??

[Sphengali]

I believe that many owners are getting shafted out there on rebuilt transmissions when it's simply not necessary:

First off - GET A OBD reader! It is essential if you want to figure this stuff out on your own. Deal extreme have Carsoft 6.5 and all the cables included for $60 - you can't go wrong.

Symptoms:
Transmission in fail safe mode
Reverse gear stopped working - when put in reverse, it would either do nothing, or actually shut off the engine!
hestitation around 60km/h, transmission felt very rough

Steps taken:
Battery was weak - replaced it with a Motomaster eliminator $160
Removed and cleaned the TCM and connectors - actually open the TCM, and use electonics cleaner to remove any corrosion. Check the ECM while there.

Was still intermittent going into TFP mode, and the check engine light on - used my OBD, and read P0721 code on the transmission. This is a pulse generator, crank shaft that take 10min to remove/install, it's $130 aftermarket part.

Cleared the 'check engine' code with ODB, and HOLY CRAP - my tranmission is working 100% normally again.

BMW wanted $3000 for a new TCM and 7 hours labour to replace all the connectors. That did not include the pulse generator or labour for that either, in fact they never even mentioned it as being a possibility.

All told, I saved about $2500 - $3000 on doing this work myself. PITA, yes - but well worth it.

If a moderator reads this, perhaps an entry in the 'how to' section under tranmsissions might be appropriate?

[m5james]

Post like these where BMW diagnostics vs trial and error lead to the real issue. I had a similar situation w/ my 7 where it wouldn't run, had it towed to a shop who wanted to do about $3500 worth of head removal, carbon cleaning, fuel system replacement to discover on my own time (in their parking lot) that it was a clogged cat once I removed the pre-cat 02 sensor. Drove the car (a 1" hole does make a lot of noise btw) to the exhaust shop, and $200 later I was running perfectly and back on the road again...and just like your situation, NOTHING they suggested I do would have even gotten them in the ballpark of what wsa wrong. Threads like these make these kinds of forums invaluable.

[powers1]

Glad you sorted it out and thanks for sharing.
Going back to the main title of your thread "unable to communicate with .....over Obd",I think a big thanks to M5James is also in order,since he suggested you to use electrical contact cleaner spray on your corroded ECU connectors/pins,which in these cases is imperative..

[HPIA4v2]

OK, what is TCM? any picture?