Fuel Injection ground wire to ignition coil

[MarkOS]

Hi all,

I'm 90% of the way through transplanting a 280z EFI system into my 260z. I'm hooking up the wiring harness, and I can't find the ignition coil ground wire which the 280z EFI book refers to.

Supposedly there's a wire which goes from the computer to the ground side of the ignition coil, however the only spare ground wire I've got is one hanging off the bottom of the throttle body? Anyone know whether the one on the bottom of the throttle body is actually the wire I'm after or whether this wire should be sticking out of my wiring harness somewhere?

Has someone got a photo of this particular wire in it's natural habitat? That would be fantastic...

[TomoHawk]

That wire is important. The (-) terminal is what the tacho is connected to. Maybe that helps.

[Devildog19]

The negative side of the coil should hook up to the #1 terminal on the ECU. If you have a signal generator hook it up to the #1 wire at the ECU side 35 pin connector and trace it out. If not you'll have to ohm it out and see where the wire goes. (unhook battery first just in case). When battery hooked up and the ignition set to "on" you should have battery voltage between #1 terminal and chassis. Hope this helps.

And Tomohawk is right the negative side of the coil sends rpm info to both the tachometer and the ECU, so maybe the ECU picks up from the Tachometer connector. Don't know for sure. Good luck.

[MarkOS]

AHA! You're right, it looks like it did indeed originally hook up to the tacho ( - ) lead, as it comes out of the harness inside the car instead of the other side of the firewall as I had originally expected...

I guess thats the price I pay for not pulling the harness from the donor car myself

Thanks for the help guys!

[Devildog19]

Cool, glad to help.