M20 won't start with key

[liljos]

my 1990 525i has had better days. the other day i go to start it and it won't turn over. i go and hit the starter to see if it siezed up but that wasnt the case since i had a mechanic some and start the car by hot wiring the starter with the key in the in position. i tried starting the car with the key again and no crank. the mechanic did the starter method and the car cranked for a bit then started up. he said it's a sensor in my ignition?

and ideas? i'm lost.

note: i never had to press the clutch pedal to start the car. it always did without that.

[whiskychaser]

Get out your DMM and put it on volts range. One lead to ground and the other to the small terminal on the solenoid. If you get 12V when you turn the key to the start position, tap the solenoid and see if it turns over. If it does, your solenoid is lazy or sticking.
If you dont get 12V, go to the fuse box. Where the starter relay would live (if you had an auto) you will find a jumper. See if you get 12V there when you turn the key. If not trace it back to the ignition switch.

[Tiger]

No sensor on key. But it is possible you might have an alarm that disable the ignition... stops it from starting although you can crank the car. OBD password disable is another thing but will not activate if you didn't do it.

Since you cannot even start the starter... it may be the ignition switch.

[liljos]

Get out your DMM and put it on volts range. One lead to ground and the other to the small terminal on the solenoid. If you get 12V when you turn the key to the start position, tap the solenoid and see if it turns over. If it does, your solenoid is lazy or sticking. If you dont get 12V, go to the fuse box. Where the starter relay would live (if you had an auto) you will find a jumper. See if you get 12V there when you turn the key. If not trace it back to the ignition switch.you're talking about the solenoid attached to the starter motor?

[liljos]

No sensor on key. But it is possible you might have an alarm that disable the ignition... stops it from starting although you can crank the car. OBD password disable is another thing but will not activate if you didn't do it.Since you cannot even start the starter... it may be the ignition switch.the car uses to have an alarm and even after I removed it, the car still started till now

[Tiger]

Alarm in your case is not an issue...

It is very possible that your starter is simply dying and needs to be replaced.

[Tiger]

Yes he is

[liljos]

Alarm in your case is not an issue...It is very possible that your starter is simply dying and needs to be replaced.the starter sounds healthy. once again the car does start but only by rigging the starter. when the key is turned all that's heard is a click but it's not coming from the starter.

[Tiger]

If the mechanic triggers the selenoid to start the car, then the starter is okay. You said it sounds normal... normal speed and sound. Since you also said the second time the mechanic started it for you is 'slower.' I am thinking it is possible he basically bypassed the selenoid and just powered up the starter.

So, in this case, you need to find out if it is the selenoid is bad or or your ignition switch... just like what whiskychaser said. Also check your battery health. Your battery may simply be dead. It is that time of the year where weak batteries dies suddenly.

[liljos]

If the mechanic triggers the selenoid to start the car, then the starter is okay. You said it sounds normal... normal speed and sound. Since you also said the second time the mechanic started it for you is 'slower.' I am thinking it is possible he basically bypassed the selenoid and just powered up the starter.So, in this case, you need to find out if it is the selenoid is bad or or your ignition switch... just like what whiskychaser said. Also check your battery health. Your battery may simply be dead. It is that time of the year where weak batteries dies suddenly.my battery was dead. and I ruled that out after having it connected to another car and tried starting it with the key ehile the other car was running. is there any way to check the solenoid? and could this be a relay problem?

[whiskychaser]

A solenoid performs two functions but think of it first as just a big switch that connects your battery cable to your starter. This is how to check it:
See if it is receiving 12V at the small terminal when you turn the key as described above. (Use a bulb and a couple of lengths of wire you dont have a meter)
If it is, turn off the ignition. Then jumper the two large terminals on the solenoid. If the starter spins, you know the solenoid isnt working.
(The other function of the solenoid is to engage the starter gear with the flywheel ring gear)

You dont HAVE to turn off the ignition but if you have got your head anywhere near the engine and it fires up you are in for a bit of a shock.

You dont have a starter relay as you have a manual and your clutch switch isnt in use anyway. Later cars have a relay as part of the immobiliser but I think your car is too early for that.

[liljos]

A solenoid performs two functions but think of it first as just a big switch that connects your battery cable to your starter. This is how to check it: See if it is receiving 12V at the small terminal when you turn the key as described above. (Use a bulb and a couple of lengths of wire you dont have a meter)If it is, turn off the ignition. Then jumper the two large terminals on the solenoid. If the starter spins, you know the solenoid isnt working. (The other function of the solenoid is to engage the starter gear with the flywheel ring gear) You dont HAVE to turn off the ignition but if you have got your head anywhere near the engine and it fires up you are in for a bit of a shock.You dont have a starter relay as you have a manual and your clutch switch isnt in use anyway. Later cars have a relay as part of the immobiliser but I think your car is too early for that.thank you. I'm gonna look into that and find out.

[whiskychaser]

Just so we are clear, the wiring diagrams for your car are here:
http://www.wedophones.com/Manuals/BMW/1990%20BMW%20525i%20-%20535i%20-%20M5%20Electrical%20Troubleshooting%20Manual.pdf

[liljos]

Just so we are clear, the wiring diagrams for your car are here:http://www.wedophones.com/Manuals/BMW/1990%20BMW%20525i%20-%20535i%20-%20M5%20Electrical%20Troubleshooting%20Manual.pdft hat looks about right..