Transmission control unit - BMW Forum

jayturk99 · 10-19-2009, 01:25 PM

I recently had my tranny serviced and it stopped the warning light from coming on and going into limp mode. I had the codes read and I don't recall what they were, but no tranny codes. One was a speed sensor code and mechanic told me that could be causing light. But has I read more could it be the TCU? Where is this unit on a 93 325is? What does it look like? Is it clearly visible, or do I have to remove items to get to it. I was going to try and clean the contacts if possible.

marti5 · 10-20-2009, 03:53 AM

You havent actually said what the problem is ?

jayturk99 · 10-20-2009, 06:31 AM

I have been getting intermittent warning light for the transmission. The rotary looking light with the exclamation point. Car drives fine w/o light, no slippage. Light comes on car bogs down into 3rd, and I have to turn off wait a few secs. then start again light goes out. I disconnected the battery over night to clear it, ran for a few days now the prob. is back. Had tranny serviced, ran for a few days now prob. is back. THinking the TCU contacts may need cleaning.

marti5 · 10-20-2009, 06:56 AM

You could try locating it...behind the battery or in the engine comparment rear right hand side I think.

Are you sure there's enough fluid in the tranny ?? as low fluid level will cause this.

jayturk99 · 10-20-2009, 12:09 PM

When the tranny was serviced, the ATF was put in car lowered, shifted through gears, raise more ATF put in and this was repeatedly done until it could take no more.