'95 E34 M50 manual M50 won't turn over.

Hi all,

I wondered if anyone had any ideas with a problem on one of our E34's?

At 275,000 miles, It's mainly a parts car now for our other 525i manual E34 of the same year. It does need to be drivable though so I can keep moving it up and down the driveway to get things down the drive from the garage.

It's been sat for a while and is normally only started every few weeks. I try to remember to charge the battery once every few weeks but forgot recently and flattened the battery. I've charged it up and even though theres 12.5V at the battery and all the dash lights up when I put the key in the ignition, it doesn't crank over when I turn the key.

I thought about the battery not having enough load so attached some HT leads from another car with it's engine running. Still nothing. I tried it again a couple of days later and it started first time. I switched it off and restarted it several times. Ok, I thought, maybe something was damp and had dried out.
A week or so later and I'm still unable to start it more often than not. It started again last weekend, but wikll not turn over since.

I've checked all the fuses and cant see any blown, although, being intermettent, it shouldn't be a fuse anyway. All the dash and guages light up as normal. Ive tried all 3 keys to see if the immobiliser had lost it's settings, but again this shouldn't be an intermettient problem.

I've removed the DME and the cotnacts are dry and clean. I opened it up and it's dry and it's perfectly dry and clean inside.

One thing I've noticed is that with the BMW INPA software and OBD cable, it doesn't seem to be able to talk to the DME/ECU. I'm pretty sure my car would have the 3.3.1 DME, but I've tried all the other options too. I can talk to the EWS Immobiliser and it sees the key etc. Under the ISN Password section it reports "ERROR_ECU_REJECTED".

I suspect the ECU/DME is not being activated when I turn the key, but being on an intermittent basis, I'm a bit stuck. If you start the car with the DME disconnected, this is exactly how the car would behave. I'm going to confirm that my laptop can talk to the DME with the same cable on my other halfs E34 when she gets home tonight.

I don't really want to have to scrap the car, but If I can't move it, I'll have to.
Does anyone have any ideas on what might cause this?

Cheers, Marcus

I've just checked on my other halfs E34 and I can't talk to any of the available DME's under the E34 Engine section on her car either. Maybe my cable was only designed for the E38 that I bought it for?

The EWS/Immobiliser thing is also irrelevant as the INPA shows the same "ERROR_ECU_REJECTED" under the Body, EWS, ISN PW part of INPA.

I supose it's possible the starter motor/solenoid is stuck but I thought I'd hear a click.

The next time you can't start the battery... grab a hammer and whack the starter and then see if it starts... I think it is the starter going bad. You can also hear a click even if the starter doesn't turn over. You can check with voltmeter on the selenoid.

Other possible reason is fusible links. Since this is a manual tranny... neutral safety switch on the clutch pedal.

I'd check you have a live coming down to the small starter terminal when you turn the key. A bulb with a couple of wires with crocodile clips on the ends would be handy if you are working on your own. If the bulb lights, you know the immobiliser isnt getting in the way. After that, I'd check the engine ground is intact. You could use a jump lead from a decent sized bolt on the engine to one on nuts on top of a shock tower. If you still have no joy, you could short the two large solenoid terminals. If the starter motor turns, you know the solenoid was stuck.

I have a copy on INPA which doesnt have the files for DME 3.1 or my auto's TCM so it just will not talk to them. I actually use DIS which does

Thanks for the ideas, I've narrowed it down a bit. I put the positive probe from my meter on the small top terminal on the starter and the other on a suspension strut tower nut. When I turn the key, I still get 0V on the meter. There is also no audible click when I turn the key.

I've taken off the under side of the steering column to check for lose wires etc and the antenna of the EWS seems undamaged and plugged into the small EWS unit on the side of the steering column.

I tried using DIS to run a quick test on the DME and the EWS but both just seem to sit there saying test in progress. My version V57, doesn't really have tailored tests for the E34 though, its a sort of generic group including E32's etc.

It is a Euro car so I dont think it has a clutch switch does it? That would make me lean towards the EWS. IIRC the actual control unit is hidden away behind the left from floor speaker and contains a starter relay. But let someone confirm before you jump in :-)
I am using easyDIS v44. The 'quick test' is a bit of a contradiction in terms - it takes about ten minutes on my car

I can't see a clutch switch, no.
I've found a little black EWS control unit on the steering column which the ring antenna plugs into, but don't think this is the main unit as it's only the size of a Zippo lighter.

I've tried the car with jump leads connected to another car which had it's engine running and it still wouldn't crank. Central locking and sunroof are fine but I have heard strange things about these cars when the battery isn't too good under load.

I tried removing the battery and connecting another battery. The first attempt I then heard a very brief try from the starter motor, but nothing more after that. I have that battery on charge now just in case. If it was the battery not working under load though, I would expect it to still start with jump leads from another car with the engine running.

Maybe having the battery disconnected for a while made the slight difference?

I found a fuse under the back seat F33 I think, which is related to the anti theft system. If I remove this fuse and put it back in ,a relay in the saem box clicks. If the fuse is there, I might try to work out what the 2 control units are in there too. Maybe one of them is the EWS.

I don't know why I didn't think of this first... Hook up a remote starter switch and see if your starter turns over. It is a simple tool that you hook up the selenoid switch to the main starter battery cable... if your connection is correct and starter is good, by pushing the remote starter, the starter would crank over the engine.

Some starter has more then one small connector so check the wiring diagram for the starter.

From what you said... I think your starter is dead. If the starter works perfect with the remote starter... then it would be something else like the starter relay or ignition switch. But hey, if you can start it up with a push button... lol... rig up the remote starter in the engine compartment... lol... you have to make sure it is in neutral and ignition on...

I've tried the upper smaller connector on the starter for 12V with the key turned and am not getting anything there. If I'm not getting 12V here would the starter switch still be worth a try?

The starter's main thick positive lead goes straight to the positive jump lead connector under the bonnet, so that must be permanantly live I'm guessing. So do I wire the positive smaller connector on the starter to the main thicker positive wire via a push switch?

There are two smaller connectors on the starter one above the thick positive cable and one below. The top one the Bentley manual reckons you should get 12V on when the key is turned. I put the positive probe from my meter on this upper small connector and the negative proble to one of the strut mount bolts.

The wiring diagram says the small black/yellow wire is the one that throws the solenoid. So yes, you could just jumper it from the main live. That could well throw the solenoid and make the starter turn. But if the immobiliser circuit is the problem it may crank but it isnt going to start. Are you using a big battery as 'slave' and heavy duty jump leads?