Help please: Car wont start after accident

[phat///M3]

Hi Guys,

A good friend of mine bought a 2002 M3 cab that had a frontal accident.

He's a mechanic and decided to do most of the work to get the car back to its former glory himself.

The car has straightened out on the rig last week, so it was time to put the engine and gearbox back in.

I appreciate this is hard seeing as the engine was taken out but any help is greatly appreciated.

He told me has hooked all the electrics back up correctly, however the car wont start.

At the time of the accident the airbags and roll bars deployed, and the "security fuse" near the battery blew, thats all been changed now.

But the car still wont start, the gearbox (SMG) is indicating 0 and you cant move it into 1 whatnot, it wont budge for 0. (Im a total SMG n00b so I dont know if this is normal or not)

Does anyone have a good idea of where to start looking?

Is there a feature when the M3 has an accident where airbags and such deploy that the car wont start anymore? There's probably a few things to look at but Im sure someone on here will be able to narrow it down, which will speed things up for my friend.

Thanks in advance for any help.

[Purvesh]

I assume it needs to have the systems reset through the diagnostic port. It's probably a safety feature like a 'kill switch' to prevent a fire or something.

Sorry couldn't be of more help...

[phat///M3]

Thanks Purvesh, normally thats all been done as far as I know.

Keep it coming guys.

[adood84]

doesn't the SMG have a safety feature thing with the bonnet if its not closed properly , so if he still hasn't fixed the bonnet that could be it ?

[madmatt m3]

not sure if the m3 has one or not but some of the older stuff had an inertia switch which is a fuel cut off in an accident, it used to be a plunger or a button that need depressing to allow fuel signal to the fuel pump. You could try googling that and see if that is any use dude

[mystic sport]

Make sure the bonnet is shut before trying to start it. There is a safety switch that gets closed when the bonnet shuts, bonnet might need shutting 'decisively'!!!

[adood84]

not sure if the m3 has one or not but some of the older stuff had an inertia switch which is a fuel cut off in an accident, it used to be a plunger or a button that need depressing to allow fuel signal to the fuel pump. You could try googling that and see if that is any use dude

yup if there is an accident then fuel will be cut off, I remember reading that the E46 has it so I'm sure the M3 would too

[mikem]

If the gearbox wont shift out of Neutral then its not likely to be some kind of cut out switch.

There are two switches under the bonnet that tell the G`box the bonnet`s closed and also one on the brake pedal.

[Davidch]

Also he is putting his foot on the brake isn't he????

Also is the dash lights coming etc?

[phat///M3]

Thanks guys,

the car doenst crank, so the fuel might be cut but that shouldnt have anything to do with the car not cranking.

So if the bonnet isnt closed fully the car wont start? Or will it start but not go in gear?

My friend just told me over the phone that the smg gear leaver seems to be stuck and the smg dash display reads "0"

[phat///M3]

Also he is putting his foot on the brake isn't he????

Also is the dash lights coming etc?

Thing is when the engine was out of the car someone turned the key, so the dash is lit up like a xmas tree.

[phat///M3]

If the gearbox wont shift out of Neutral then its not likely to be some kind of cut out switch.

There are two switches under the bonnet that tell the G`box the bonnet`s closed and also one on the brake pedal.

I assume the switches are where the bonnet latches go in right?

[Raja_SMGII]

If it's not even turning then the fuel supply is not the issue [that btw is terminated by the battery cable with the fuse you mentioned]... Sounds like something is gone awry with the SMG as you mentioned. Is it not throwing any fault codes? Maybe at worst have a BMW tech look over it for an hour to diagnose the problem? Good luck mate :)

[mikem]

If someones turned the ignition on with the engine out and all lights have been on since, then I have no idea.

[phat///M3]

If someones turned the ignition on with the engine out and all lights have been on since, then I have no idea.

He said they are going to clear all the codes and try then.

[adood84]

If someones turned the ignition on with the engine out and all lights have been on since, then I have no idea.

I'm guessing since the key was turned while engine was out , the car's ECU is going to all have all kind of errors , my best guess would be that there are a bunch of codes that need to be cleared first

[Davidch]

Thing is when the engine was out of the car someone turned the key, so the dash is lit up like a xmas tree.

Yeah sounds like something with the SMG is wrong. Relay or something?

[Davidch]

Also has he plugged everything in? I mean everything, like the climate control panel everything?

[alexsh1]

Check the starter just to make sure its working

[phat///M3]

OK so he has checked mostly everything.

The issues are as follows:

No power at the spark plugs, the smg shifter doesnt move, and the starter doesnt do anything, he has checked the starter and it works, just not when on the car.

Anyone got any pointers?

[mikem]

Is there power going to the SMG Steve ?

[phat///M3]

Is there power going to the SMG Steve ?

As far as I know it is Mike, my m8 said it makes the pump/electric sound. Is there anything to look out for?

Could the car have gone into security mode cos of the accident, or maybe when the key was turned by some muppet when the engine was out?

[Black Sabbath]

I know its obvious but have you rechecked all the earth points?The fuel cut off wont stop the car turning over either,it just wont fire.

[phat///M3]

Thanks Mark, will tell him to check again, Ive already told him this a couple of times and he says its all plugged in and wired up the way it came.

[Black Sabbath]

I know Steve,but sometimes the obvious gets overlooked.If it works out of the car it certainly sounds like an earth problem

[mikem]

If the SMG pump is pressurising but it wont move out of gear then I would think its one of the 2 switches under the bonnet or the switch on the brake pedal.

If my bonnet is slightly open or if my foot isn`t on the brake, then it does exactly what you describe. Ignition lights come on but nothing else and the gear lever is locked in position.

[clubsportmatt]

The display needs to read 'N' for the car to start. If the bonnet is open you can still start the car but it prevents a gear from being selected, so you can't drive like it.

[phat///M3]

The display needs to read 'N' for the car to start. If the bonnet is open you can still start the car but it prevents a gear from being selected, so you can't drive like it.

Apparently it reads "0" any idea why that might be?

[sparkyunlimited]

they changed the dash from having a 0 to an N around 2003-4

My 2003 has a 0, my mates 2004 has an N

Nothing to worry about.

[ccfj1]

Steve, has the car got an tracker/immobilizer fitted, if so has it kicked in and is therefore stopping the car from starting (via starter and/or coils)? or perhaps locking the SMG into 0 (and not N).

Just a thought.

[phat///M3]

Steve, has the car got an tracker/immobilizer fitted, if so has it kicked in and is therefore stopping the car from starting (via starter and/or coils)? or perhaps locking the SMG into 0 (and not N).

Just a thought.

Thanks John, weve thought of that too, but as far as we know there is no immobiliser fitted. Maybe the car goes into some sort of security mode when the airbags deploy etc?