Engine won't start

[Maxtek]

So, I have absolutely no experience working on cars.

Earlier I was installing my new rear number plate lights, went to start the car to check they worked and the engine done nothing, the lights on the dash showed up (all of them).

I then unplugged my newly fitted rear plate lights and tried again, same thing. Then checked that the exterior lights worked, pulled the light switch and pressed my hazards, a strange noise was coming from the right hand side of the drivers seat, under the carpet (I'm guessing that's the wires from the battery which is in the boot?), the lights do work so I doubt the battery is faulty. (that noise might have been unnoticed before due to the loud engine/exhaust).

So I locked the car, set the immobiliser and went to do some research. Came back, everything seemed normal yet the car still had the same problems. I decided I needed some help, so again, locked and set immobiliser, this time the immobiliser didn't want to work.

As I said before, I have zero knowledge with working on cars, the best thing I could find was relating to the starter motor and trying the diagnostic plug start but now with the immobiliser issue I'm just lost as to what to do.

1990 325i Sport
Meta Systems Immobiliser

[Grrrmachine]

the lights do work so I doubt the battery is faulty.

The energy needed to make a few bulbs glow is about 1% of the energy needed to crank six pistons and a 15kg flywheel at 700rpm. Considering the energy needed to power your locks was then enough to kill your locking system, it seems that you've truly knackered your battery in some way; either by creating a short while you worked on the lights, or by leaving the interior lights on for hours with a battery that was already on its last legs.

Buy a 5-quid multimeter from the supermarket, set it to "20 V", and put the electrodes on your battery terminals. If the reading is below 12.4V, your battery is dead. If it's below 12.2V, your battery is properly goosed. If it's below 12V, it's probably time for a new battery.

[Maxtek]

Ah right, well there's a multimeter somewhere in the house, I'll go dig it up. Not to say the battery is knackered but it does look fairly new, either way, its worth a try.

Thanks!

[Maxtek]

Found the multimeter, tested the battery, got a reading of 10.9V. Took the battery out the car, it's now charging in the house. I shouldn't really be surprised that it's dead, the car hasn't been driven in the 13 days that I've owned it

[Grrrmachine]

Sad to say, a lot of car sellers will put a known knackered battery on the car to sell it. As long as it holds a charge for 24 hours it's "good enough" and the new buyer doesn't know any different.

If it's been that low for a long time (two weeks) then you'll be very lucky to rescue it to a useable state. It's worth splashing out on a decent battery now just for peace of mind.

[Maxtek]

Yeah I did have some suspicions of the previous owner, there was a lot of 'little' things that I've found that anyone could have fixed easily, which is kind of what I'm doing now. I'm just dieing to drive it, so I'm getting it fully road legal at the moment and then next week the wallet is coming out, needs a new clutch, tappets adjusting, tracking done, guess I can now add new battery to the list

Thanks for the help man!

[Grrrmachine]

No problem. If you really want to learn mechanics, there are guides for all the things you mentioned in the wiki, and the tracking and tappets can be done with very little in the way of tools (although the clutch is a different story!)

Well done getting your hands dirty with E30 ownership

[capnmchl]

For future reference, if you don't have a multimeter to hand, the best thing to do is switch on the wipers. If they move slowly then it's a sign your battery is possibly (and most likely) low on charge.

Also, with E30's, if the car won't start, and the interior fan doesn't work, chances are it's something to do with the excitor wire for the starter motor. I know because my tends to fall off now and again.