key ignition non-functional

[saridout]

i'll preface this with the fact that i rebuild my engine and refreshed the engine bay which involved removing everything from it. i didn't touch anything under the dash.

it's definitely not the starter; the engine turns over when the starter solenoid is connected directly to the battery. when the key is turned, the dash and body lights come on, but when the key is fully engaged, the seat belt alarm comes on and there's a clunking sound coming from the area above the fuse box.

i've got continuity between the yellow wire on the starter solenoid and the black/yellow wire going to the ignition switch, but when i've got 12V going to the switch, it never gets to the yellow wire at the starter solenoid. is there anything else i'm missing that i should check?

edit: forgot to say that my battery keeps going dead, and it was fine before the rebuild.

Edited October 19, 2009 by saridout

[260zCaliCar]

First the dumb question... Did you try putting on your seatbelt? Assuming you did, The easiest first thing to try (at least this is what I would do) is simply try starting your car without sitting in the driver seat. If that doesn't work, disconnect the pressure switch under your driver seat and try again. If it still doesn't work, disconnect the switch under the passenger seat... Actually, do you have a bunch of stuff on the passenger seat that might activate the pressure switch? That would cause your symptoms...

For further investigation, in the engine bay next to the fusible link (near the battery) is the seat belt warning relay. It's connected to the Ignition Interlock unit located by your fuse box along with the seat belts and seat pressure switches. When you go to turn on your car, the interlock unit will either send power to the seatbelt warning relay which will activate the buzzer and warning light OR send power to the starter motor. Sounds like this is the problem, the question is why.

[saridout]

i pulled the 6-prong connector off the bottom of the seat belt warning relay and shorted the yellow and yellow/black wires together, bypassing the relay, and the car starts! thank you!

so does this mean that it's the relay that's the problem, or one of the seat belt switches? i took the black platform that the relay is bolted onto apart and repainted it, so i'd assume it's the relay and i messed it up somehow. or is it the interlock unit... argh, i'm worse with electrical stuff than i am at math :/

[260zCaliCar]

You said that you hear the interlock unit click in the passenger side foot well by the fuse box. Something is triggering it, that it turn is triggering the seat belt relay and the car doesn't start.

I'd say it was the seat belt relay if the interlock system was not clicking, but it is. So I would look to the seats and belts, start with the pressure switches, driver side first since that seat gets the most use. It's easy to disconnect them, it's right under the seat, you can't miss it. Once you know which side is bad first test the pressure switch and if it's working right, then check the seat belt switch. At least this is how I would trouble shoot this.