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Old 12-24-2011, 09:06 AM   #1
wildcat293
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Join Date: Mar 2009
Location: Rochester, NY
Posts: 185
My Ride: 325xi
Post DIY: Replacing TCC Solenoid on GM 5L40E (A5S 360R/ A5S 390R) - Fix GM No Reverse!

Symptom:

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.

Root Cause:

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.

Background:

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.

Requirements:

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**

Procedure:
  1. Follow the ATF change DIY (Click Here!) to remove the trans oil pan. Stop after step 6 (removing the old filter).
  2. Clean your hands frequently. Have lots of lint-free rags handy. Every time you touch dirt/rust wipe them off. You don't want to get any dirt inside the trans!
  3. Locate the TCC solenoid.
  4. Pop out the retaining clip. I used a plastic trim puller to do this, I'm sure the less paranoid can use a screwdriver just fine. The TCC solenoid will be free, but you can't get it out. You need to drop the valve body slightly to clear the trans case.
  5. Partially unscrew the 9 bolts shown (Do not remove!). I had to drop the ones near the TCC solenoid around " and the farther ones less. Do it a little at a time until you can maneuver the TCC solenoid free. Don't force it - the connector is fragile!

  6. Pull up on the connector tab and disconnect the TCC solenoid from the cable. I have heard of this breaking easy. If it breaks don't panic, you can secure it with some steel wire or a tiny zip tie. This is not ideal however so take it easy. The tab on the TCC solenoid is really tall so you need to pull the tab pretty far to disconnect it. I recommend you remove the connector after you have the TCC solenoid free so you can see what you are doing. After I did this DIY I think cutting the retaining tab on the old solenoid (NOT on the connector) might be a better option. This is the worst part of the DIY.
  7. Look at the old TCC solenoid and the clip so you know where the clip needs to go.
  8. Grab the new TCC solenoid and the clip. Push the TCC solenoid into the valve body with light but firm pressure - the regulator inside the hole is spring loaded. Push the clip onto the solenoid locking it in place.
  9. Push the connector back on to the TCC solenoid.
  10. Check that no wires are stuck under the valve body. Hand tighten the 9 bolts you unscrewed to bring the valve body back into place.
  11. Torque the bolts in order (1-10 skipping #9) to 10 Nm. If you got confused and loosened #9, the torque on this is also 10 Nm.

  12. You are done! Check the following before proceeding:
    a. TCC solenoid is connected to the wire harness
    b. TCC solenoid spring clip is pushed in all the way
    c. All 9 bolts have been torqued to 10 Nm
  13. Continue with the ATF change DIY from step 7 -installing new filter (Click Here!).

A few more pictures:

Front of valve body


Rear of valve body
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Last edited by wildcat293; 12-25-2011 at 11:13 AM.
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