Strange electrical problem, no 12 volts anywhere.

The only thing keeping me from finishing up my red 90 is this electrical glitch. With a new battery connected I only get 12 volts right around the fender solenoid, on either side of the fuse links, the alternator, on the big cables exiting the area but nowhere else. The IRC module has no voltage on it and the power distribution box behind the battery is dead. Jumping the solenoid does crank the engine. A big yellow wire exiting one of the fuse links has 12v on it but an identical yellow wire coming out of the same wire bundle is dead. Nothing inside but maybe +-.5 volt at the ignition switch, no dash lights, nothing at the cigarette lighter, nothing. I can't find any unplugged connectors, don't see any missing or blown fuses, and have run out of places to look. It's got to be here somewhere. What could cause this?

Bad grounds,do a search for grounds i believe that there are 3 of them.

92strokedbird said:

Bad grounds,do a search for grounds i believe that there are 3 of them.

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If you're checking for 12V with a good ground on your probe, looking for bad grounds is a goose-chase. Check for a loose connection somewhere. Try reseating everything you can. Start from the battery and work your way down the 12V lines and see where the power stops. Mystery electrical problems are one of those time-consuming jobs that mechanics hate and charge up to wazzoo for, so if it gets frustrating, that's normal.

I think you've blown a fuseable link, tho. It's safe to replace those with an inline fuse as long as it's weather tight when you're done.

I think it's a fusible link somewhere, too, but don't where to look as the cables tend to be difficult to follow. where else would fusible links be? Is there one under the dash? The grounds appear to be good. The neg battery cable goes to the block, the ground strap is in place on the right side of the engine to chassis, and the small ground wire on th neg battery cable is connected. I need to know where that yellow wire goes and connects. I bought the car this way and we rebuilt the engine so I have no idea what could have happened. I'm cleaning up the interior as well as it was pretty foul with mildew. I think I've beaten a 20lb bag of sand out of the carpet.

Mike Puckett said:

I think it's a fusible link somewhere, too, but don't where to look as the cables tend to be difficult to follow. where else would fusible links be? Is there one under the dash? The grounds appear to be good. The neg battery cable goes to the block, the ground strap is in place on the right side of the engine to chassis, and the small ground wire on th neg battery cable is connected. I need to know where that yellow wire goes and connects. I bought the car this way and we rebuilt the engine so I have no idea what could have happened. I'm cleaning up the interior as well as it was pretty foul with mildew. I think I've beaten a 20lb bag of sand out of the carpet.

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Fusible links are not allowed in the passenger compartment by the DOT, I believe. As far as I know, the fusible links are all in a cluster running off the starter solonoid. Use a pin and stab the wires to check for 12V on the side of the link furthest from the battery. Don't stab the link itself (skinnier part) as you'll likely blow it. Then seal it (the hole from the pin) up with electrical tape or a drop of epoxy.

That's what I've been doing to test it. So far I've got voltage going out but not going anywhere. I need to look at a car with the engine removed so I can trace the wire bundle. If it's not a fuse link then maybe a connector. I take it nobody's ever had this problem before.

One Fusible link goes to the fuse panel under the dash, one goes to the EEC, one goes to an underhood harness 'somewhere' (I think by the driver-side corner by the windsheild, but don't quoute me) and you prolly have 1 or 2 more because I am not thinking of an SC (I'm thinking of an 87 XR-7 Cougar). The yellow one goes to the under dash panel, I think, but that's a fuzzy memory from a time I'd like to forget. There should be a blue one also, right? And one that is dark brown with an orange stripe? The blue one goes to the EEC, if your colors are the same. The Haynes manual has an excellent diagram for the 87 XR-7...

Mike there is a large gauge yellow wire that runs uncer the header panel under the pass side headlight. I know it feeds the fans and some of the power connections for the starter solenoid.

There is also a ground wire that runs to the bolt in the rear of the drivers side cyl head where the fuel rail bolts to the head.

Jeff

You sure you did not connect the main battery lead to the wrong post on the solenoid? There is no fusible link between the solenoid and the fuse box.

Fusible links are on the IRCM feed and the Alt. feed.

The battery feeds to the + terminal on the solenoid and then directly to the main fuses in the fuse box.