Won't start with the key..... - BMW Forum

harryinsaudi · 12-22-2009, 02:18 AM

I've had the engine out.... head gaskets replaced etc etc. all back together all connected up... turn the key nothing happens. Well all the lights come on but the starter won't kick in. Short the starter and the engine fires instantly and runs great... bit impractical though! All worked fine B4

My local BMW fixer, says the "computer needs reprogramming to accept the key?" Another chap says to take the battery off for 2hours then try again.... Some one else says you have to press the brake 3 times after doing that before trying.....

I'm 4 hours on a car trailer from the nearest dignostics..... any ideas?

marti5 · 12-22-2009, 02:41 AM

So can you lock unlock doors with remote?,as for battery off you could try this but 20 minutes is ample.

harryinsaudi · 12-22-2009, 02:49 AM

yep remote works with the doors/boot, tried the spare valet key but still the same

marti5 · 12-22-2009, 02:57 AM

As you can start it via a short from the starter, I doubt its down to programming the ECU as it would have gone in to imoblise mode and would not fire up...have you checked all your fuses ? and rechecked all you wiring connections.I can give you instructions for key re programming but I dont think that will do anything.....

marti5 · 12-22-2009, 03:03 AM

E39 Key reprogramming:

Re: how to program for the key ?

harryinsaudi · 12-22-2009, 06:36 AM

OK, So... fuze 15 "Diagnostics" was blown (7.5A)... Changed that, hit the start key engine tried to turn. Fuze blew. Go up to 10A Fuze ( I know naughty), eng turned over then fuze blew....15A fuze, engine started then the fuze blew after about half a second... Batt Caption stays on, engine runs fine. SO? Alternator overcharging /short into the diagnostic link somewhere?

At least i think i know what it isn't any more!

Thanks Marti

marti5 · 12-22-2009, 07:17 AM

You must have short somewhere in the bay as you said it was fine prior to engine removal, its just a case of checking every wire connection and especially ground points to the engine, there's not much more I can help you with from here...

harryinsaudi · 12-22-2009, 10:44 AM

yep, thinking that the alternator output is shorting through the diagnostic fuze as the car will start then the fuze goes... nipped a loom on the way in/out... i'll undo the alternator connector and then see if it blows... if it's the other route... ie starter power input,/starter earthing maybe i'll just fix a "ricer" start button / relay and bypass the short.....~ Velly funny...

harryinsaudi · 12-24-2009, 12:02 AM

I've found the short, it's the oil pressure sensure at the pump. Melted wires so it got B hot. If i disconnect the sensor then all is well. It's going to take a few days to get a new one and it's oil pan off etc.... Q is can i run it until then or do i risk the ECU going into safe mode which will cause me even more grief. H

marti5 · 12-24-2009, 04:15 AM

Personally I wouldn't run it as this will as you say put the car in safe mode due to the ECU not getting a response from the sensor and getting all the usual lights on the dash, I have heard also that it can and will send an error to the transmission via the ECU to the EGS and lock the transmission, which is a a good safety measure as the ECU basically says "No oil Pressure" were not going anywhere then...obviously it wouldn't lock the box if you were driving at the time, it would go to limp mode until you stopped turned it off and tried to go on re-start and then lock the box...