Need help chasing down an electrical gremlin on the '89 MJ

[XJs4Ever]

I'm not sure wtf is going on here, but about a month ago I replaced my CD deck. Immediately I noticed every time I started it, my settings were lost. Checked the 12v constant memory and 12v switched wires - both ok. Returned it for another radio of the same type - same thing.

 

Yesterday I said screw this and put the old deck back in. Now NOTHINGS working! No dome light, no radio, the aux fan and spot lights come from the fuse block - they're also dead. Clock glows but no display.

 

Heater blower still works, dash lights work, wipers, cig lighter, fuel pump, headlights turn sig brake all ok. It starts and runs fine.

 

Most fuses in the block are dead as well as half the single slots, but a couple are still hot. But here's the wierdest part...

 

The hot wires from the fuse block that fed the radio, aux fan and spots are now grounded. I put a meter on them and have continuity to the chassis, for chrissake! How can so many hot wires be shorted to ground now?

 

My thoughts are, one [or more] of the dozen relays those stupid Renix-era Jeeps have has suffered a melt-down. I can find no smoked wiring anywhere. I put a test lite on the constant 12v memory wire and started the truck and the light dimmed alot as it was cranking but it stayed lit.

 

Before I start systematically replacing every dang relay on it at the cost of $12 each, I know theres some great minds on here and I'm beggin for some direction to go that I havent thought of yet.

[Akula69]

I would suggest that you check any of the locations where you have worked in the dash area - meaning anytime you moved a dash component - as you might have pinched a portion of the harness.

 

Failing that, remember that there are only three 'hot' wires in the harness that feed the radio: One is always hot (feeds that clock as well), the next is switched with the ignition (have you done anything with the column?) and the third is for the power antenna (if your truck had this option the relay will be on the heater core case about where the passenger could kick it and short it out).

 

Finally, you might have had a momentary short that melted the brass receiver which holds that fuse inside the fuseblock. If so, its 'meltdown' could explain the remaining problems that have cropped up in the block.

 

A sure solution would be to pull the dash (easier done then said - 8 bolts and it swivels) and trace the wires in the harness. If you found your problem - great - if not at that point a replacement interior harness/block it relatively cheap at the pick and pull (about 19.00 here)

 

Good Luck!