DIY: Do It Yourself
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|12-24-2011, 09:06 AM||#1|
Join Date: Mar 2009
Location: Rochester, NY
My Ride: 325xi
DIY: Replacing TCC Solenoid on GM 5L40E (A5S 360R/ A5S 390R) - Fix GM No Reverse!
On cars equipped with GM 5L40E transmissions only (A5S 360R/ A5S 390R):
Loss of power/no movement in reverse (RWD), Loss of power/no movement in forward and reverse (AWD). Often happens only when the engine is cold.
As far as I know, this problem does not generate any codes, or any dash lights. If you have a dash light, take the car to AAMCO for a free diagnostic to get the code read, you probably have something else wrong. I *think* the computer can detect problems with the shift solenoids, but cannot detect problems with the TCC solenoid.
Unlike ZF transmissions, the GM "no reverse" is often the failure of the TCC/PWM Solenoid. I think this leads to the torque converter not fully "gripping". I am further speculating that PWM = pulse width modulated, or that this solenoid is rapidly turned on and off to vary the pressure inside the torque converter, allowing the amount of torque being transferred to the transmission to be adjusted by the computer. This is probably one of the mechanisms used to cut the power when the wheels slip. When the solenoid fails, the PWM no longer works as intended, and higher RPMs and warmer, less viscous fluid is needed to get the pressure built up to move the car. This PWM cycling must wear this solenoid out faster than the rest. Or I could be completely wrong. Regardless, if you have a GM transmission and it isn't shifting right, this is an easy DIY, and probably worth a try instead of spending $2500 on a used transmission that is probably in worse shape than the one you have now. I have read some speculation that the internal passages/pressure regulator needs to be replaced and reamed out. I did not need to do any of this to fix my problem. The only part I replaced was the TCC solenoid.
TONS of information here (thanks Neil!) http://forum.e46fanatics.com/showthread.php?t=706809
Read this entire post.
ATF fluid change DIY (thanks James!) http://forum.e46fanatics.com/showthread.php?t=438667
Overall I found this DIY much easier than I expected.
In addition to the tools listed in the ATF change DIY, you will need:
24327532013 Pressure regulator,convert.lockup clutch
24331423599 Clamp (optional, just in case you lose it!)
E8 "Reverse Torx" socket
Small torque wrench (10 Nm)
**OPINION** If you are doing this DIY you have a GM 5L40E transmission, you don't need the BMW fluid. Anything Dexron III rated (Valvoline MaxLife DEX/MERC ATF, RedLine D4 ATF are popular) is 100% compatible with your current fluid, and was designed specifically for the 5L40E. Furthermore, if you have already flushed your fluid recently, you may want to save your fluid in a very clean container, and re-use it. **OPINION**
A few more pictures:
Front of valve body
Rear of valve body
Last edited by wildcat293; 12-25-2011 at 11:13 AM.
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|reverse, slip, solenoid, torque converter, transmission|
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