'81 troubleshooting, not starting, dies on turn signal

[marty3d]

I just bought a 1981 Spider that is in overall excellent condition but it has gremlins in the electricals. I picked it up yesterday and started to examine the issues last night:

- Charged battery - hadn't run for over a year.
- Engine turned over quickly and easily.
- Fired a little with no throttle applied, tried to run, but died whenever any throttle was applied.
- I concluded that it has spark and the cold start injector is working - but the main injectors aren't doing their thing.

Looked up the wiring diagram...
-Traced the main fuel injector power supply to the relay set which is below the dash on the passenger side. I detached the computer so I could reach the relays and just wiggled them to try to make better contact.
-The car fired right up and ran smoothly. Headlights, dashlights, and stereo all came on normally.
-When I tried a turn signal, the engine died immediately - like cutting the spark. High or low rpm made no difference. I noticed some new wiring under the hood, so I suspect the PO or his mechanic introduced some jumpers into the system.

[RRoller123]

Best approach probably is to trace the turn signal wiring through with a schematic. Turn signal and Hazard Switch problems are really common with these cars. Amazing how many comments they get in this forum! There are various schematics available online that give color codes and are pretty easy to follow, and they can be purchased for thin money from the various suppliers.

[majicwrench]

You are loosing 12v or ground when you are using the TS. Easiest place to start would be the coil + term. Hook voltmeter to it, turn TS on see what happens. If it stays at 12v, find + term on that pwer relay, do same thing. Find ECM, find it's power wire, same thing.

[marty3d]

Thanks for the advice! I dug out my volt meters and am ready to dive in. I did look up the connections online - schematics are available by searching this forum. I found that the turn signals receive their power via fuse 1 which is also connected to the ignition. On firing the car up, I measured 12v at fuse 1 (F1), then 9v, then 6v, then 9v... When I applied the turn signal, it dropped to 5v. It hovered at 6v for a while, then went up to 13v with the engine running, then back to 6v. I disconnected the rear tail light connector and that made no difference. Conclusion: the supply to F1 has a poor connection.

The power delivery to F1 comes from a pink wire that leads to the ignition switch. Power gets to the switch via a brown wire that runs to the battery terminal on the starter motor. As I use the ignition switch - on and off several times with the engine off - the voltage changes. Perhaps the ignition switch is the culprit. Next step is to measure the voltage drop across the switch - it should be zero.

Well, I couldn't resist...took the car out for my first drive.