e36 non start, immobiliser issue I think

[iguana]

94 3.0 M3, BMW immobiliser, changed batteries, on reconnection it won't start?

All lights up but wont un-immobilise

Anything obvious to check??


Key fob = one button not 2, siren under bonnet says BMW 3T

So the advice I've found on web for BMW 3G EWS doesnt seem to be applicable

[naetype]

What battery did you change it for, I'm assuming you got one with enough cranking amps to turn that big old motor round? Off the top of my head I think they need over 600.

Otherwise get out the old multimeter and check you're getting power to the fuel pump and starter motor. If you are that almost certainly rules out the immobiliser.

Here's a good guide for checking the starter : http://www.type2.com/bartnik/starter.htm

Also check your earth strap (L/H side lower from the front) at this age they tend to work themselves loose and corrode.

Edited by naetype on Wednesday 24th February 12:01

[iguana]

Def not the battery & is immobiliser, no fuel pump whirr, hazards flash etc, battery was off my other M3, only swapped as its lighter & this is a track car.

[Travis Mcgee]

I may have dreamt this, but i am sure that in another thread, someone said that sometimes the ECU has to be re-set after a battery change.

[naetype]

Tried a bump start or changed the battery in the key fob? Obvious I know but often gets overlooked.

ETA: If I recall correctly the EWS and 3T immobilliser are on seperate circuits. Basically 2 immobilisers.

ETA2: There is a way of bypassing the EWS module for testing so let us know if you want to go down that route and I'll PM you what I can remember about the procedure.

Edited by naetype on Friday 26th February 10:16

[iguana]

So today after 2 months of this I give up, pushing it out my garage to load on the truck to go to my pals garage to see if he can sort it, I demo to him what it does & the bugger starts!

No idea why, battery has been on charge yes, but has been for a month?

It could be something as simple as fob batteries going flat & the battery swap was just co-incidence?

Well wizzed about in it all day & started fine each time i stopped.

V bizzarre ah well least I can trackday the old girl next wk hurrah

cheers