Background: I recently acquired 86’ TA with 305TPI. It’s been sitting for ~4yrs. It ran fine when the guy parked it. He recently hooked a battery charger up backwards. It makes it hard to troubleshoot when it's been sitting AND something potentially damaged it. I don’t know if it is ‘decay’ that is causing the problem or the charger that caused the problem.

As the title states, nothing works when I put the key in the switch and turn it to any position. However, the headlights, horn courtesy lights, door locks, power mirrors all work. When I first hooked up the battery I got gauge lights when I turned it to the on position. If I tried to crank it, hit the brake, turn signal or even turn the radio on, the dash would black out. The fuel pump never kicked on or anything. The courtesy lights, etc. still worked though. After a few tries, nothing happens when I turn the key now. Once out of 25 tries I may get the door buzzer, but even that goes away when I turn the key.

Things I’ve checked so far: Battery is brand new. I get 12.5 volts from terminal to chassis, so the ground is ok. 12.5V from starter solenoid terminal to ground. I took the 3 fusible links off of the starter solenoid and measured the resistance across the links. The worst I got was .7 ohms so they seem to be okay. I wiggled them to check for weaknesses or partial burns and I didn’t see any change in the resistance. I checked the fuse and fusible link by the battery and both of them are ok. My courtesy lights work so I know I’m getting power at the fuse panel. All fuses in fuse panel are good. I don’t get a voltage drop on the battery when I turn the key to on, so I don’t think it is a short anywhere.

Questions: Can an ignition switch fail so completely that you get no response in any position? How can I go about testing the switch? The ignition switch feels like it moves through all the positions fine, but I don’t get anything. The rod seems to move ok. It’s like I’m not getting any voltage through the switch.
Is there a fuse or fusible link anywhere else that I may have missed? It seems the only things that aren’t getting power are the ignition and the ECM/Fuel Pump. Fuse is good in the panel but when I turn the switch, I get no voltage at the fuse slot.

Sorry for the long post. I’ve been lurking and searching on this sight for several weeks now and there’s a ton of good info on here. I couldn’t have made it this far without the forum and the search function. Thanks in advance for any ideas you may have!

 

UPDATE: the ignition pin in the C100 was bent. I don't know how it ever ran.

I still can't get the fuel pump to do anything. I don't know if it's froze or if I'm just not getting juice. Deos anyone know the color code/pinout for the fuel pump relay harness on the 86? I used search and found three different answers. I want to jump 12V to the signal wire and and see if the pump works.

Thanks again.

 

you can run a 12v wire to your SES plug underneath the dash, i believe it's the bottom left...i also think that instead of copper color it's the only silver colored terminal, that will send a 12V signal to your fuel pump and thats how you check it according to the Haynes manual.

 

Hey, thanks for the reply! I'm 5.0 mustang guy, so this has been a totally different experience!!!

I applied 12V from the battery to the port you mentioned and got nothing. I could hear the next relay in line click (MAF I guess?) but the pump did not fire up. I crawled under the back and disconnected the harness at the fuel pump. I measured the voltage there between tan and black and got no voltage. I disconnected the 12V from the port and checked the ground on the plug. It was good.

Here's where it gets weird again. I got the same resistance reading from tan to ground as I did from black to ground???

I ran out of daylight. It looks like I may be having problems with the tan/white wire. I'll do some more checking when the sun comes up.

 

I'll have to go home and take a look at my bird, but if you wanna take a look into your car right now...go to the tech articles and check out the '86 wiring diagrams...and camaro and firebird both had the same 5.0L TPI so, it may just be enough background to understand what your looking at.