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Old 06-08-2012, 10:07 PM   #9
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Join Date: Jun 2012
Location: Charlotte, NC
Posts: 2
My Ride: '00 540it, 97 B4 TDI

The PWM/TCC solenoid can be unplugged & have no effect on reverse whatsoever.

If your transmission does not engage reverse then there are 3 likely scenarios:

1. the transmission fluid is low

2. there is excessive wear in the low/reverse clutch assembly

3. there is insufficient system pressure due to other mechanical wear/internal leakage

Reverse is an entirely mechanical function, on this, and most other transmissions of the era.

Positive results gained by performing the described repairs can be attributed to either;

A. Correcting a low transmission fluid level

B. Increasing the viscosity of depleted/sheared atf

C. Improving the friction coefficient of incorrect/exhausted atf

I'm all about DIY guys, but this is silly. To the OP, go to, or better, (automatic transmission rebuilders association) & do some research.

Torque converters do not "grip", they are toroidal couplers: Two fans, facing eachother in a fluid medium. TCCs are irrelevant to the operation of reverse & until the late seventies, did not even exist in everyday automotive applications. PWM TCC's came about as a solution to clutch lock-up "BANG" & the tendency towards "on/off" solenoids to stick "on", resulting in stalling when coming to a stop.

I was referred to this post by a customer that had me install a TCC solenoid in his E46 328i. I thought he was trying to address the more common SES light fault associated with a failed TCC. Little did I know.

Look. I'm not bashing here. There is nothing dangerous posted. i have read dangerous DIYs before. No one is going to make their car any worse if they follow your instructions carefully. Your write-up is exquisite. It's just wrong, is all.
jaypeesm30 is offline   Reply With Quote