Electrical Problems

I have a 95 XJ with the 4.0 liter engine. A couple of times recently when I have had the heater running on high and the radio on I have lost power and the heater and radio go dead. When this has happened I pull over and turn off the Jeep and restart and it comes back on. I am not real savy on electrical issues and wonder if anyone else has had this problem or could tell me where to start. Any help is much appreciated.

pick up a Haynes guide for your year and look in the electrical section. You will find schematics for the electrical. If you don't know how to read the schematics just ask here. most of it is straightforward with the wire colors labeled and there should be a chart in the beginning for what is what. If you follow the one for the radio and the heater I believe (but not sure) that they are on their own circuit off the fuse block. that being the case if loosing power to both then their circuits on the fuse block are probably fed by a common source. That source is probably connected to a relay that is activated by your ignition key. You've got some digging to do. There is a possibility that the ground is bad but I would think that they have separate grounds. Easy enough to figure out if you jumper them to the chassis (the metal body of the heater or radio or their respective ground wire) and see if they work. It will help to have a multi-meter to test things out to to see if you have power when this happens. I would put money on it being a relay or ignition issue. I know enough to get me into a little trouble so if I can help any more let me know.

It also sounds like an auto resetting breaker but I don't know if there are those in these vehicles. If it only happens when the heater is on high and radio is on that you are drawing the most amps then. If there are bad connections or that breaker is getting weak then it (if indeed there is one) is tripping and resets when you shut things down (killing power to it and it cools down and resets). Again that would be shown in the schematics if there is one.

Since it is the radio and the blower fan I would check the battery connections first and then the ground wires from the firewall and engine to the battery. Then check the ignition switch and wiring harness connector to the igniton switch for loose and / or burned contacts. Most of the power, or control power to relays for all the electical items goes through the ignition switch.

Then lastly check for loose fuses. If you can wiggle the fuse and power comes and goes you have found the problem, but those two items usally are on separate fuses so check the battery connections and ignition switch first.

Mike McGinness
South Houston

Thanks for the help I will go through and check these things out. It usually only happens when I have the heater on high and the radio on so maybe it is a relay. I will keep ya posted on what I come up with. Thanks again.