'95 525i Intermittent Starting Issue

[blk84]

I'm relatively new to the E34 (experience with E30's mostly) and I'm having an intermittent starting issue that I can't figure out... I've searched this forum and others and can't find similar symptoms.

The car is a '95 525i automatic with around 144K miles. About every 3 days (approximately 10 starts) the car will not start. Everything works- lights, radio, starter cranks, etc. What I have noticed is on the instrument panel an 'S' appears where 'E' or 'M' usually are right next to the 'P' for Park. So, I know the car won't start when I see the 'S'! I get the Automatic Transmission Control See Owner's Manual message as well.

I've had the car in the shop and it is not showing any codes.

If I wait several hours (8+) it will start fine like nothing is wrong.

I've had the shift lever replaced and the symptom persists. Any ideas?

Thanks!

[David325e]

Do you get no activity when you turn the key? Like it won't fire or theres nothing. I'd venture a guess that the a-m tranny switch is fubar'd and the car won't start, similar to turning the key with the lever in D is what I'm thinking.

[blk84]

The starter cranks but it just won't start. I haven't done all my homework with the fuel system yet either because the 'S' and transmission message has me thinking transmission.

I recall reading that the sunroof switch is interchangable or at least a suitable stand in? I'll try that.

[David325e]

Hm on my e34s I get nothing when I try to start the car in D. Having the starter crank would be like turning the key with a manual car in 1. So I'm not thinking switch now. Are you getting fuel and spark when this condition happens?

Whats the conditions when it doesn't start. Engine temp, ambient temp/moisture, recent use etc.

[paanta]

If you unplug the battery and plug it back in, does it clear itself? Does it happening at any particular time of day?

I'm relatively new to the E34 (experience with E30's mostly) and I'm having an intermittent starting issue that I can't figure out... I've searched this forum and others and can't find similar symptoms.

The car is a '95 525i automatic with around 144K miles. About every 3 days (approximately 10 starts) the car will not start. Everything works- lights, radio, starter cranks, etc. What I have noticed is on the instrument panel an 'S' appears where 'E' or 'M' usually are right next to the 'P' for Park. So, I know the car won't start when I see the 'S'! I get the Automatic Transmission Control See Owner's Manual message as well.

I've had the car in the shop and it is not showing any codes.

If I wait several hours (8+) it will start fine like nothing is wrong.

I've had the shift lever replaced and the symptom persists. Any ideas?

Thanks!

[blk84]

Changing out the A/M switch with the sunroof switch did not help- still shows 'S' and won't start.

Disconnected battery cables for about 10 min and the problem persists.

Plan to try jumpering the fuel pump relay- any other ideas? Not sure why the 'S' shows up if it isn't a transmission electrical issue.

Here's a summary of the conditions when I've had the issue:

Problem first happened on a sunny day, temp in the high 40's. I was going up a steep hill and once the road leveled out the transmission went into safety mode. It restarted after a couple of tries and I got home. I noticed that the bulbs on the cluster for the A/M and Gear designation blew out. Took it to the shop where they diagnosed it as a bad shifter assembly which was replaced, along with the cluster bulbs. Drove it again for about 3 or 4 days and after about a 6 mile drive (sunny, dry day temp in the 50's) on the highway it happened again- cluster showing 'S' P and no start. Shop replaced a main 80A fusible link (located near battery) which they said was cracked. Shop drove it the whole next day and no issues. I drove it for 3 days and had the issue again (overcaset, 40's dry)...let it sit for about 5 hours and it still wouldn't start. Came back the next morning (rainy, 40's) and it started right up and I drove it home. Let it sit in the garage for a week. Started driving it this Monday to work, lunch, etc. I started it 9 times before failure today. Today is rainy, about 60 degrees.

In every case in which the car didn't start the 'Automatic Transmission See Owner's Manual' message has come up.

Thanks for all of the thoughts/ideas! Hoping to learn more places to look...

[russiankid]

I suspect the gear selector switch is not making a good connection. Its located under the wood trim.

[David325e]

You have any running problems with the tranny? I mean shifts etc. when its working. If not this does seem like a switch or selector issue to me. For some reason the selector or the comp is thinking that is in the wrong gear and causing fuses/bulbs to blow, and causing it to erroneously go into trans program of the wrong gear.

Have you considered a bad tranny comp? Maybe an OG can comment on that being bad or a way to test it.

Does your selector lock into the gear you select or is there some wiggle to it?

[blk84]

I had the whole shift lever mechanism replaced by the shop after the first time I had this issue. I didn't notice any play in it before I had these issues but I did ask the shop to see it and it looked somewhat worn-but I don't know if it was any more or less worn for a car that age. There definitely is no play in it now.

When you mention transmission computer are you referring to the TCM located in the ebox?

The transmission is fine during driving- smooth, no slippage