Electrical Issue

Hi, So I am working on a 2 door Chop Top and all the electrical was working just fine up until last Friday. I went to go move the jeep and I had no fuel pump, interior lighting, Stereo, Gauge back lighting. The only things in the cabin that work right now are the cigarette lighter, Heater Controls, and the Gauge cluster its self minus the fuel gauge. I have power to the fuse block but nothing past it. I have pulled the dash apart to get a better look and all looks ok. I'm not sure were to start looking any ideas?

When I did the chop I made sure to unplug all the wires that went up into the hatch so I'm pretty sure that it isn't a short in the rear section of wiring.

The Jeep is a 1990 XJ 4L 5spd NP231....
Matt

sounds like a ground issue somewhere near the rear.

Ground issue in the rear: Fuel pump? Yes. Interior lighting? Maybe. Radio? No. Gauge back lighting? No.

Power to fuse block but nothing past it: Cigarette lighter? Maybe. Heater controls? No. Gauge cluster? No.

You probably have a couple of different problems at work here as your symptoms are not consistent.

You have a mix of switched/un-switched circuits. You say you have nothing past the fuse box, but some of the circuits you say are working are fused. You definitely could have ground problems at the rear in particular for the fuel pump.

It is multimeter time.

Now you say that I probably have a ground issue in the rear of the truck, The only ground wires that I can find back there is the main on for the tail light harness. Tomorrow im I'll take a good look under the truck but last time I crawled under there I didn't see anything....

Tonight a buddy and I were able to get some were I think. We pulled the fuse block out a bit and started wiggling it around trying to get the test light to the wires behind it and I guess from all the movement of it it did something because now the dome light and cd player work (no sound comes from the speakers). I still do not have gauge back lighting or fuel pump thought. Also I noticed that the yellow ish brown wire for the fuel pump when the key is on it has very little power (test light is very dim) not sure if it is supposed to be like that or not....

I also pulled the bracket that holds the Computer in place and when I pulled the computer down I notice to wires a "White / Black" and a "White / Purple" neither were connected but looked like if they were they would go to the larger of the two plugs.

Any other ideas?

Matt

Don't worry about those two wires, they were cut when the dealer did a TSB update to the CPS/CKP crank sensor connector.

Quote from TSB:

"Locate the crank position (CKP) sensor connector (Figure 1). Remove the connector from the EEC harness by cutting the two CKP sensor wires close to the connector. These wires should be white with black tracer, and violet with white tracer"

maybe i missed it when reading, but did you test the ingnition switch at the bottom of the steering column?

or if its anything like my 89 5spd, bad connections in the fuse block from hydraulic clutch fluid leaking on the contacts and corroding/destroying them.

Ok, good to know about the TSB.

No you didn't miss it, I never did test the ignition switch at the bottom of the column, I did how ever check to make sure it was plugged in properly and it was. It doesn't look like any clutch fluid has leaked over the fuse block but I'll take another look.

Got a little further with it today. I started probing wires with my test light and I decided to test the fuel pump wire for the 1000x time and what do you know it had power this time. But the pump still wouldn't turn on. I pulled the pump bench tested it nothing tapped it a few times and it started pumping just fine, Put it back together and the truck now starts and runs just fine. But I still do not have gauge cluster back lighting or speakers, but I think the speakers is something different all together so that's not a big deal.

Matt

[email protected] said:

Ok, good to know about the TSB.

No you didn't miss it, I never did test the ignition switch at the bottom of the column, I did how ever check to make sure it was plugged in properly and it was. It doesn't look like any clutch fluid has leaked over the fuse block but I'll take another look.

Got a little further with it today. I started probing wires with my test light and I decided to test the fuel pump wire for the 1000x time and what do you know it had power this time. But the pump still wouldn't turn on. I pulled the pump bench tested it nothing tapped it a few times and it started pumping just fine, Put it back together and the truck now starts and runs just fine. But I still do not have gauge cluster back lighting or speakers, but I think the speakers is something different all together so that's not a big deal.

Matt

Click to expand...

back lighting could be a bad bulb or bad headlight switch.

89xj said:

back lighting could be a bad bulb or bad headlight switch.

Click to expand...

Agree.

Thanks for the help guys. I'll probably fix the cd player and leave it at that for now as long as everything else keeps working. Kinda odd that just all of a sudden it stopped working then all of a sudden it started working again. Oh well must be a Jeep Thing haha....


Matt