Electrical gremlins

[rullemj]

Hey guys!

 

Haven't posted anything in a while, mostly because the Jeep's been working flawlessly for a while :rolleyes:. Maybe I'm hitting an issue that's already been adressed, in that case feel free to redirect me. If not then maybe we can all learn something new.

 

My problem started a week ago. Driving down the road i hit some big bumbs and the car went completely black (I know now this is because it burned through the fusible link for the igniton positive) but had no clue then. Had a burned smell in the cab while i coasted to a stop so checked under the dash at the fuse panel and found the wire plugged into the "Batt" terminal looking pretty fried and wiggling. Probably been a while in the making.

 

Got towed home and got to looking around at the basics; burned fuses, obvious corrosion, loose terminals etc. Didn't find anything that stood out except my fried "Batt-connection" so I went ahead and wired a postive lead into the igniton switch (red terminal) and the power was back.

 

Checked the fusible link which was broken. Replaced it with a standard 15 amp blade-fuse. Might go back to a link later.

 

So power's back into the igniton switch, reading full voltage out of the yellow terminal aswell as one with I think smaller gauge purple wires. However there's no voltage coming from orange or brown. Is this correct? As I understand these are accessory something? There's no power to the stereo or gauges except lights.

 

When I put the electrical system under load with both the heater in full, lights on and window-motors working I blow my 15 amp fuse and loose ignition power. Am I using the correct amp fuse? or is there a still a short somewhere? Tried putting a fresh postive lead into the red ignition terminal thinking the wire itself might be bad but same problem. 

 

My MJ's an 88 Laredo. The Batt terminal I spoke of is used in junction with the Ign terminal for some relays to drive an automatic lowbeam feature as I understand it, I live in Sweden and can't find anything plugged into these slots on fuse-box diagrams from the US.

 

I'm no electrical expert but think myself somewhat logical, however I feel stuck, sometimes you can't see the obvious staring at it for too long. Fresh thoughts are much appreciated :bowdown:

 

Thanks

 

 

[87MJTIM]

Here is a link for the 88 electrical FSM.

 

This may help you trace the gremlins away.

 

http://comancheclub.com/topic/12083-electrical-manual/

[HOrnbrod]

Check the ignition switch for proper alignment and/or burnt contacts. THIS thread will help.

 

And yes, a 15A fuse is undersized with all those devices (lights, heater blower, window motors) running at the same time. Try a 25A fuse.

[gogmorgo]

The automatic low-beams you're talking about are called Daytime Running Lights. It's an option in the US, but legally required in Canada and other jurisdictions. The modules do go bad sometimes, but I'd worry about your other problems first.

[rullemj]

Thanks guys. I appreciate the help.

 

Will read up on the linked threads for sure.

 

I'll report back when I've had a chance to get a proper look at the switch and try a bigger fuse as suggested.

 

Have a good one.

[ScottJeep]

When you mentioned the heater fan it triggered thoughts of this nightmare of mine...

 

http://www.jeepforum.com/forum/f11/definitive-blower-motor-blown-melted-resistor-switch-wire-fix-580627/

 

http://www.jeepforum.com/forum/f11/definitive-blower-motor-blown-melted-resistor-switch-wire-fix-580627/

 

I'm still amazed that you don't see Jeeps on the side of the road burning.  While looking for parts I probably opened up 50 XJs in the YJ. 

Several SHOULD have been there because of dash fires. Things were melted beyond belief.