1994 525i tranny problem (a curious one)

[pcross]

Here's a curious tranny problem. 1994 525i, A4S27/310R tranny. When I start the car, dash light shows E P. Goes into reverse and backs up just fine. When I shift to D, nothing. If I rev the engine a few times, the tranny engages and the Trans Program light comes on. I then shift to L and it goes into 1st gear. I move off and shift to 2, it shifts. Then to 3, it shifts to 3. then to D and were cruising along in 4th gear, 60 mph at 2300 rpm. Runs like a dream. As I slow down to a stop, I down shift to L and start all over again. OR, when I start the car, I immediately move the MODE switch to M. Then, it shifts and runs in M D mode just great... 1st, 2nd and 3rd. Settles into 3rd at speed, 60 mph at 3300 rpm. I think I have a 2nd/3rd or a 1st/2nd/3rd/4th solenoid valve problem in the tranny. I switched the EGS unit to a new one and the switch made no difference. Tranny has new filter and was properly filled. BTW, all shifts are smooth as silk. No clunks, no jerks. The tranny itself performs flawlessly after I go through all the steps I listed above. Any ideas? Thanks.

[RobPatt]

there's a lot of oddities which cause this.... so.

- search and keep a list of trans program threads, note that many are for the 540's auto trans...

- check charging system
- recheck the EGS and all cables seated properly ?
- hook up a diag computer and see (then write, clear and check next time it happens) any stored tranny codes in the computer...

Good luck, at least you can still get around....

Here's a curious tranny problem. 1994 525i, A4S27/310R tranny. When I start the car, dash light shows E P. Goes into reverse and backs up just fine. When I shift to D, nothing. If I rev the engine a few times, the tranny engages and the Trans Program light comes on. I then shift to L and it goes into 1st gear. I move off and shift to 2, it shifts. Then to 3, it shifts to 3. then to D and were cruising along in 4th gear, 60 mph at 2300 rpm. Runs like a dream. As I slow down to a stop, I down shift to L and start all over again. OR, when I start the car, I immediately move the MODE switch to M. Then, it shifts and runs in M D mode just great... 1st, 2nd and 3rd. Settles into 3rd at speed, 60 mph at 3300 rpm. I think I have a 2nd/3rd or a 1st/2nd/3rd/4th solenoid valve problem in the tranny. I switched the EGS unit to a new one and the switch made no difference. Tranny has new filter and was properly filled. BTW, all shifts are smooth as silk. No clunks, no jerks. The tranny itself performs flawlessly after I go through all the steps I listed above. Any ideas? Thanks.

[pcross]

RobPatt...Charging system checks OK. I reset the cables to the ECU and the EGS after cleaning them and applying dielectric grease. I run Carsoft 6.5 and diagnosis reads "EGS module - OK" No stored tranny codes. That's why it's so curious. Thanks.

[pingu]

Maybe the transmission switch (that tells the transmission ECU in which position the auto lever has been placed) has got bad internal contacts and needs cleaning. I think there's been a post on this - maybe by Shogun.

[whiskychaser]

Sounds like the box may be good but the mode switch is playing up in drive. Its just a switching matrix that gives different voltages to the ECU like this:
Switch 1 2 3 4

P 1 1 0 1
R 1 0 0 0
N 1 1 1 0
D 0 0 0 1
4 0 0 1 1
3 1 0 1 1
2 0 0 1 0

1=+V, 0=0v

Worth getting the mulitmeter out to check?

[pcross]

Pingu and Whiskeychaser: Thanks. My next step will be to pull the shift lever switch and thoroughly clean the contacts. Then, I'm going to run Whiskeychaser's voltage check (that I hadn't thought about). Thanks to both of you. I'll get back on the results.

[whiskychaser]

when I start the car, I immediately move the MODE switch to M. Then, it shifts and runs in M D mode just great... .

Hang on a mo. Is MD like sport mode on yours -it changes gear automatically but just revs higher between gears? And doesnt M limit you to 3rd gear on yours? That would account for the higher revs. If its working fine in MD but not ED then it may just be the 3 button mode switch. Stand to be corrected, but I think you can check it using the sunroof switch. Selector switch is worth checking but dont want you wasting your time

[Chad535]

Just a curious question guys.......could it happen that the contacts get dirty or corroded so that the cluster would show the right shift position while the ECU wouldn't resulting in strange behaviors ?

[Chad535]

Sorry for the second post but i forgot to say that i have the same problem with reverse....i have to wait a minimum of three minutes before i get the tranny locked in reverse and meanwhile if i try to rev high i will get a trans program error.

[pingu]

From what I've heard, if you need to wait 3 minutes to get into reverse then the valve body of your auto box may be kaput. There's a "check valve" which is a plastic ball; when it wears down it get stuck within a bore of the valve body. It's not a problem I've had but you'll probably find loads of stuff if you search this forum using words selected from: plastic ball check valve body reverse Kirk