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 ¼" 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

just in case i need it.

On a side note, I wonder how many good transmissions are getting scrapped for this simple fix!

Thanks for the guide!

If/when my tranny goes bang I will undoubtedly find this invaluable.

John

I have 2001 330 CI. I have the No reverse issue. If put in reverse, the car moves very slowly but no throttle can make it move any faster, It moves as a snail. On an inclined surface, it wount budge. 2500 dollars to get it semi rebuilt with he drums changes and 5k to change it with a remanufactured tranny. HELP .. Even if I drive it for a 30 min. the reverse still does not work... How can I make sure that it is not the solenoid. EuroTechOfHolland.com, the ones who are going to be fixing it say that it is def the drum and can not be the solenoid. Although they have not even looked at the car..

if you are sure you have a GM, I think it is worth trying a $60 part vs $2500.

You will not do any more damage than you already have.

Also if it does come to a replacement, I suggest you find a place that will install a junkyard transmission. I don't think remans are worth it, but it is up to you!

I am experiencing this issue with my GM transmission. Did the fluid change and it has worked perfectly for 5 straight days now. I did order the TCC solenoid, and plan to drop the pan once more, and change the solenoid and fluid again. kinda worried about messing with the valve body, but it sounds like you just have to drop it a little to get clearance. Is it as easy as it sounds?

it was pretty easy. The hard part for me was removing the oil pan, aluminum bolts suck.

you may have just had low fluid - maybe a small leak on your cooler lines?

thank you for the information. It is really easy to follow your instruction, save me a lot of money. It is running fine now for couple days.

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 howstuffworks.com, or better, atra.com (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

Well, I really have my doubts that it's just the fluid but I'm willing to see if that's really the case. I just bought a 2000 323i that has the GM trans a couple of months ago and it started very, very randomly not engaging into reverse. I bought it from a BMW dealership and it came with an extended warranty so I took it up today and had them check it out. Of course they couldn't get it to fail and it isn't showing any fault codes so they didn't want to mess with it. They checked the fluid, etc and sent me on my way for a $118 diagnostic fee, whatever.

But let's see if the fluid fixes it. I know someone who rebuilds transmissions and is an atra member and is actually next door to where I work. I'll have him drain the fluid, flush it, and put in new and we'll just see what it does. I hope that does work, it would be great... but I really have my doubts.

It certainly can't hurt. Go for it.

In regards to the customer's car I mentioned, after replacing the TCC solenoid, filter, pan gasket & fluid, it shifted beautifully. However, it was apparent from the tool marks on the drain & filler plugs that it had been serviced before, and underfilled. It took a little over 7 quarts of Redline D4 to fill up... & there were no external leaks.

the latest post may be true, but my TCC solenoid had exploded, as i have read about in a few posts here. bits and pieces of the old solenoid may have gotten into the valve body causing pressure issues... is that a possiblity

@jaypeesm30

Well, yeah of course it won't hurt anything. I come from a background in racing and we built everything ourselves and pretty much either something works or it doesn't. So we'll see if the fluid change fixes it and go from there. The fact that it's so extremely random on my car and the rest of the time it works perfectly makes me think that it's something more than just the fluid but I'm certainly willing to be pleasantly surprised. I would work on it myself because I like solving mysteries like this but I don't have a lift or the time to tear into it right now.

Just replaced the solenoid to fix the intermitant no reverse . Had to drive a few miles before reverse came back , keeping my fingers crossed .

Originally Posted by jaypeesm30

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

Then why did this fix my problem and several other peoples problem? No idea what the point of your post was, bottom line is this fix works. I think your customer needs to find a better mechanic =P

I have been fighting with my E46 "no reverse" My transmission would fail to go into reverse several times a week when reverse was needed I changed TCC still had trouble. Before changing transmission I decided to pull and dissemble valve body. (what do I have to lose) Be careful with separating the valve body many little balls. I found what seemed to be valve body gasket or clucth disc material pieces in the ball seats and in the valve bores. Pulled and cleaned all spool valves, put them back together.

I am an experienced technician but not with BMW, Transmissions.

I have attached several pics. you will see that the VB gasket ripped, Just put it back together the way it was.(again Nothing to lose) The pic shows where the balls are located on the gasket plate. you can measure the location and put them in the proper hole on the valve body.

PS. BMW has a service sheet telling you to change the TCC. if the repair fails they recommend replacing transmission.

So Far SHIFTS GREAT and I have Reverse!!!

First post hope it is right.

Hoping it will help others.

Kevin

Originally Posted by wildcat293

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 ¼" 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

_nr_

Great post ! This is the first time I have heard of this solution . Please post again after a month or so to see if it really did fix the problem because my BMW would be fine for about a month at times then just when I thought it was safe to pull into a parking space , WHAM ! No reverse again Thanks Ken

Originally Posted by kpgary

I have been fighting with my E46 "no reverse" My transmission would fail to go into reverse several times a week when reverse was needed I changed TCC still had trouble. Before changing transmission I decided to pull and dissemble valve body. (what do I have to lose) Be careful with separating the valve body many little balls. I found what seemed to be valve body gasket or clucth disc material pieces in the ball seats and in the valve bores. Pulled and cleaned all spool valves, put them back together.

I am an experienced technician but not with BMW, Transmissions.

I have attached several pics. you will see that the VB gasket ripped, Just put it back together the way it was.(again Nothing to lose) The pic shows where the balls are located on the gasket plate. you can measure the location and put them in the proper hole on the valve body.

PS. BMW has a service sheet telling you to change the TCC. if the repair fails they recommend replacing transmission.

So Far SHIFTS GREAT and I have Reverse!!!

First post hope it is right.

Hoping it will help others.

Kevin

_nr_

good to know people still have options if solenoid alone doesn't fix it
I bet the gasket is the same for all 5L40E, some googling might find it

the disintegration of that paper gasket is probably the cause, clogging up the solenoid and sometimes more than that.

I have been good for over a year after changing just the solenoid

You can use this too.It is cheap but it works great.

http://www.ebay.com/itm/New-1-2-Driv...item3a666acf8b_nr_