Engine dies when I turn on marker lights, headlights and hazards.

[DiamondSchwartz]

So I just finished up my M30 swap in my 91 318is , and everything is great except for an electrical issue. I should mention that I bought this E30 without the M42 engine in it. The problem is that anytime I turn on the marker lights, the low beams, the high beams, or the hazard flashers, the engine will die when stationary and have a power interruption when driving. The interruption last only a second and power resumes and the car drives normally. Ive already replaced the battery and the alternator as both were bad, but I bought a O'Reilly's alternator. I also have a spare factory 7 series alternator that tested as good. Also, when this issue happens, my friend noticed that my alternator exciter circuit will drop to 0 volts. Voltage across the coil isn't affected, nor is the ignition pin on the C101 connector. If anyone can help with this, that would be great.

[e30damen]

bump - Derek maybe you should post this in a more active sub-forum like the swap forum?

[101]

It sure sounds like the car is losing voltage when you turn on some of the accessories. Perhaps not at the coil, but at the DME?

Will O'Reilly's run a charging system test free of charge? I'm pretty sure AutoZone will. Do that first. If that passes, then trace the wire running from the battery to the DME. There is a fusible link in that circuit that can give some issues.

[AndrewBird]

Is there an aftermarket radio installed? Could be wired funky. Someone might have grounded the illumination wire or tapped into the wrong wire coming from the cluster or something.

[ahlem]

Pull the relays for the accessories mentioned and see if you have the same problem.
That would at least identify whether you are grounding at the switches rather than the circuits that run through the relays.
I'd then add back a relay one at a time to see which one causes the problem.
What changes did you do to the electrical system when you did the swap?

[DiamondSchwartz]

Pull the relays for the accessories mentioned and see if you have the same problem.
That would at least identify whether you are grounding at the switches rather than the circuits that run through the relays.
I'd then add back a relay one at a time to see which one causes the problem.
What changes did you do to the electrical system when you did the swap?

I didn't pull any relays, but I did pull fuses.

Pulled fuse 24 (hazards), started engine, pressed hazard switch and reinstalled it's fuse: engine died.

Pulled both fuse 22 and 23 (both marker lights) turned on lights, reinstalled fuse 22, engine ran. Removed 22 and installed 23, engine still ran. Reinstalled 22 and 23 both, engine died. Going to try the headlight fuses tomorrow. I'm too busy with Independence Day right now.

Also there is an aftermarket radio installed too. I'll look into it tomorrow.

[DiamondSchwartz]

So, I somehow got the marker light and the hazards to stop killing the engine, but the headlights are still causing the problem. I'm starting to wonder if the coil is playing a part in this. I'm currently using a ring type coil, and every other swap I see, people have been using the rod type coil. I'm kinda wondering if I got the wrong coil installed.