E36 non-starter after battery disconnect

[McSam]

Hi guys,

I hope someone has some experience of this, as my car seems to have immobilised itself and I need to get it running as soon as possible! I have a 1997 E36 328i saloon.

The back story is that the car had been standing for a while, and the battery depleted. I removed it to charge it, reinstalled fully charged as I have done before without issue. I didn't try to start the car at this stage. We then fitted a new set of suspension struts, during which this connector was removed while the main battery was still on:



I thought little of this, it looked clearly non-OEM so I assumed for the CD changer that was once added in the rear. However, with all our work complete, the car won't start. The dashboard lights up as usual, the fuel pump primes and sounds strong as ever, but when going to starter stage, nothing happens. No clicks, no attempt to crank at all.

Jumping it to really eliminate the battery as a cause had no effect, and we cannot bump-start the car. It seems like something has disabled the starter and ignition system.

I believe the car is fitted with the 3G Mk2 alarm system, as I have a key and fob like this:


I've never used this fob, the car was fine with just the key. The fob lights up fine when you press a button, but appears to do nothing to help start the car now.

I've been hunting for the alarm/immobiliser system's control unit. I didn't see anything of note under the steering wheel:



But behind the glovebox, this big metal enclosure on the left looks a likely suspect. I'm going to try and remove this, and see if it contains the alarm system which can be reset like this..



Am I barking up the wrong tree? Could this be an EWS II fault instead? I'm a bit stumped to be honest, and so far nothing I've tried has had any impact.. Big thanks in advance for any help you can offer.

Some additional photos of the setup under the bonnet, the siren type I have:



It has an on/off switch, which was previously turned off. Turning it back on has no effect - I think this is only for the siren itself, not the whole system. In any case, it doesn't make a sound.



The positive side of the additional wiring shown above at the strut top:

Edited by McSam on Sunday 6th July 19:52

[LanceRS]

If you have not done it already, check all the fuses. I know it sounds obvious, but mine did something similar and I wasted loads of time pulling the dash out and fiddling before I had lightbulb moment and found a blown fuse.
Still no idea what caused it, but it hasn't happened again.

Good luck.

[McSam]

Ah, that's one check I forgot to mention, I did test all the fuses and no issues there. Thanks for the reminder though, simplest things often forgotten..

As an update, I've had the alarm module out - it is the type I was expecting, and following the guide linked to above to short various pins to lock the car and arm the alarm (I checked by setting it off, I think this bit impressed my neighbours), then made it unlock and disarm the alarm without issue. Still no joy.

I'm down to three possibilities, unless there's anything I'm missing..

• EWS II key sensor ring is not correctly recognising the key. This is apparently quite common, but I don't think the fuel pump should prime if this is the case?

• Starter motor jammed/at dodgy brush point/died. It's always been a very strong starter, firing the engine up right away, It's turned a lot with our attempts to bump start so shouldn't be stuck or still at one random broken point. Does not tally with failed bump start.

• Ignition switch broken. I don't know much about this, the key behaves properly up to stage 2 but just won't engage the starter. Does not tally with failed bump start.

[Joe Sp]

The alarm control unit is the black box to the left of the metal one behind the glove box. I think the metal one is the engine ecu.

[Joe Sp]

I forgot to say, when you put the glove box back, attach the upper trim piece (with the vents) to the govebox first and fit them as one unit, this stops the glove box sagging issue you see in many e36's.

Good luck.

[McSam]

Hi Joe - yep, you were right, here's a couple of pictures of the box intact and with its "lid" off so you can access the pins. This can be achieved with a single crosshead to remove the trim, glovebox and alarm box, then a slim flathead to prise the lid up!





Anyway, that's just for reference since it appeared not to be the problem. Some research elsewhere showed a couple of cases where a key can be unlearnt by being left in the ignition as the battery discharges - we may have done this, leaving the key in to keep the steering lock off while we worked on the car for two days. The battery was flat thereafter..

I stopped by the dealership just now and had a chat to them about it. Turns out they've had identical symptoms in the workshop with the same type of key, after they left it in a car overnight. They say there is no learning process for these non-remote style keys, so a replacement was the only way they could fix it. New one on its way to me for the princely sum of £46. I also have a new EWS antenna ring for the ignition (£25) and if the current one looks knackered, I'll replace it just in case.

Happily, BMW put ten (or so) code slots in the EWS II system and the keys you get with the car naturally only take up three or four of those. From the chassis number, they can order a new key with one of the blank, unissued codes so it should not need any initialisation or learning. This is a big advantage when your car won't start and is not in a dealership

Anyway, will update when the key turns up, hopefully Wednesday.

[jz325i]

Something else you might want to consider, is to check the earths, esp the engine earth.

[helix402]

Forget the alarm as a cause, it's a 3G EWS. There is no immobiliser in it. Hope you get it sorted.

[iSore]

Despite being EWS, the 3G system still connects into the ignition switch wiring - I've taken quite a few out. Best thing for that alarm is to very carefully remove it and stick it in the bin. These were dealer fitted and use neat plug connectors so all you do is remove the wires and plug the original car loom wires back together. The big alloy ECU is the ABS/ASC ECU, an 094 unit.

[McSam]

jz325i said:

Something else you might want to consider, is to check the earths, esp the engine earth.

Thanks, I'll give them a look - though our underbonnet inspection to make sure there was nothing obvious disconnected didn't reveal much.

I'm inclined to agree about the alarm box after that little test, but it's interesting to hear that it doesn't control the immobiliser on this variant, I presume all that's done by the EWS.

This is heading towards being a dedicated track day car, so is deleting the alarm really as simple as unplugging it and re-completing the relevant circuits? The box is able to control the central locking too, and I don't want to stuff that up!

No fresh news on the car, since no key arrived yet.

[McSam]

Hi guys,

To update this for anyone who finds it when searching for help on a similar issue, the key was indeed at fault!

As I mentioned earlier, the dealer techs said they'd seen identical symptoms when leaving the key in a car overnight while the battery discharged, this unlearnt the key and while ignition second stage would work normally, the car wouldn't allow cranking, injection or ignition. I have heard that on some occasions, cranking is possible, but the car still won't give ignition/injection so still won't run under any circumstances.

A replacement key was £46 from the dealer, arrived in two days (take some ID and your V5C with you), and the car runs perfectly now!

Many thanks to everyone for their advice and input

[LanceRS]

Glad you managed to get it sorted

[tgr]

Nice one McSam!

[McSam]

Cheers guys! It was a relief to say the least, what with Curborough booked for the Friday..

Here's a short clip of what getting the car running let me do