No power at ignition

[Mehoff]

Need some help Pelicans -

Quick back story: '88 Carrera race car (original wiring) with a kill switch. Car was raced in the rain last time out. Went to pull out of the trailer after sitting for two weeks to prep for next race and zero, ZERO, power to the ignition (nothing lights up; no gauges, warning lights, nothing). Important points:

• Verified power from battery to kill switch to ignition switch
• Power loop does not return to ignition switch
• Checked all grounds - good
• Checked all fuses - good (even checked leads to fuses)
• Checked all wires for corrosion/oxidation and nothing

I've never seen this before.....just literally dead at the switch. Logic would suggest the switch is dead, but I've never heard of one of these going like that. Any advice/experience?

Even though the dash didn't get wet while running the car, could the moisture have hung something up inside that switch that needs to be shaken loose? (note: I didn't think of that until after I got home so haven't been able put a hammer to the switch to attempt the "universal fix")

Thanks

[strictly]

I dont know how a kill switch works, presumably its just an on off switch and would be wired like in the path from the ignition swicth, to the rest of the ignition circuit. So when you turn the key power jumps from 30 (battery positive) to 15 at the key then travels to the kill switch, which if on (killed) stops there and if off (not killed) to the beginning of the circuit for the ignition

Can you put a continuity meter across the terminals of the kill switch (other wires disconnected) and then turn it off, to confirm the switch works (continuity going on or off). If it works then test continuity on the feed to it to where ever that starts (power "in") and continuity on the other side "power out".

One of those 3 will have problems with continuity and that is where you should chase, assuming a kill switch is really just an on/off switch in the ignition circuit

[Mehoff]

Originally Posted by strictly

I dont know how a kill switch works, presumably its just an on off switch and would be wired like in the path from the ignition swicth, to the rest of the ignition circuit. So when you turn the key power jumps from 30 (battery positive) to 15 at the key then travels to the kill switch, which if on (killed) stops there and if off (not killed) to the beginning of the circuit for the ignition

Can you put a continuity meter across the terminals of the kill switch (other wires disconnected) and then turn it off, to confirm the switch works (continuity going on or off). If it works then test continuity on the feed to it to where ever that starts (power "in") and continuity on the other side "power out".

One of those 3 will have problems with continuity and that is where you should chase, assuming a kill switch is really just an on/off switch in the ignition circuit

Kill switch was the low hanging fruit and I have 100% confirmed the issue is not there.

[ischmitz]

Check the plug under the dash. I believe there is a plug that connects the ignition switch loom to the fuse box. If that came undone it's like you never put the key into the ignition.

If that doesn't work go systematic. There needs to be power at the ignition switch with the battery connected and the kill switch on and working. Get out your trusty multi meter and find Term30 and confirm it is powered at all times. It's a red wire. Term30 is also present in the fuse box F1 and F2) and allows hazard lights and some other stuff to work without a key in the ignition. Term30 is also present in the DME relay socket (thick red wire).

If there is no power work your way back towards the battery. The +12V are "getting lost" somewhere. From there it becomes TERM15 (hot with ignition on) when you turn the key on. That powers lots of things and the DME relay. If that doesn't get powered you could have a bad ignition switch (electrical part).

Ingo

[Mehoff]

Originally Posted by ischmitz

Check the plug under the dash. I believe there is a plug that connects the ignition switch loom to the fuse box. If that came undone it's like you never put the key into the ignition.

If that doesn't work go systematic. There needs to be power at the ignition switch with the battery connected and the kill switch on and working. Get out your trusty multi meter and find Term30 and confirm it is powered at all times. It's a red wire. Term30 is also present in the fuse box F1 and F2) and allows hazard lights and some other stuff to work without a key in the ignition. Term30 is also present in the DME relay socket (thick red wire).

If there is no power work your way back towards the battery. The +12V are "getting lost" somewhere. From there it becomes TERM15 (hot with ignition on) when you turn the key on. That powers lots of things and the DME relay. If that doesn't get powered you could have a bad ignition switch (electrical part).

Ingo

plug checked (disconnected, cleaned, reconnected) and put a meter on all items mentioned above and confirmed hot. The DME relay has two thick red wires, one of which was hot, the other not (probably because that goes hot once the key is turned).

Pretty sure it's the ignition switch at this point and am curious if anyone else has had this happen.....confused on what could go bad inside this thing

[ischmitz]

Yes - happens all the time. There is a pair of contacts inside the ignition switch for TERM15 and the surfaces burn from arcing. Once that happens contact resistance goes up and accelerates the deterioration of the contacts. Easy to replace.

Ingo

[Mehoff]

Originally Posted by ischmitz

Yes - happens all the time. There is a pair of contacts inside the ignition switch for TERM15 and the surfaces burn from arcing. Once that happens contact resistance goes up and accelerates the deterioration of the contacts. Easy to replace.

Ingo

.....and if moisture happened to get into that switch you could all but guarantee an arc between surfaces. Much appreciated Ingo, I think I have my answer.