no signal from ignition to starter

[knick_knack]

I asked about this on the M20 page last week and didn't get any responses so I thought I would post it here, too. If that's frowned upon let me know and I'll take it down.

The issue that I am trying to solve is basically that my ignition key doesn't start my car, but I am able to start it using the diagnostic plug. What steps should I follow to find where the fault is?

Here are the events as they occurred in case my summary leaves something out:

I went to start my 1990 325is the other day after it had been sitting for two weeks and it didn't crank. I then tried starting it by connecting pin 11 to pin 14 in the diagnostic plug while the key was in the "run" position. First time I tried it did half a crank and then died, so I hooked up the battery to a running car and tried again and it worked.

Now I can start the car with the key in the "run" position and a wire from pin 11 to pin 14 of the diagnostic port, but I want to find out why I can't start it with the key and what I need to replace/fix so that I can.

[Das Delfin]

first and easiest thing to try would be check the ignition switch for a loose connection

[knick_knack]

Thanks. I'll take off the steering wheel and the steering column cover and visually inspect those connections. Is there also a way to check their continuity to the starter? Or is there a place between the ignition and the starter to test continuity?

[Das Delfin]

yeah you can check for voltage across + and ground at the switch when it's on. Then trace the signal path to find out what could be obstructing it. Google "we do phones bmw e30" and you'll find an electric troubleshooting manual. It's super useful for stuff like this. Has wiring diagrams, problems and their solutions

[knick_knack]

Took off the steering wheel and started tracing back the connections from the ignition switch to the wiring harness when I heard an electrical arc noise and smoke started coming from the steering column. Got the battery disconnected and then proceeded to remove the ignition switch. One of the wires had completely burnt off all the insulation before I got the battery disconnected. I'm really glad that it didn't catch fire and yet made it so easy for me to identify what needs to be replaced.