ignition switch red wire hot with blower on

[muley88]

1996 Cherokee Country. When we turn on the heater/ac blower, the red wire coming into the ignition switch connector from the battery gets melting hot after a few minutes. This wire has a splice on it which replaces the part just before going into the connector, I suspect because it has melted before.

Seems like this would be a short somewhere. Ideas? Thanks.

[citizen@large]

Be patient friend, an expert will be along soon enough...

In my Limited opinion, a 'short' or 'ground fault' should blow a fuse before getting anywhere near 'hot' enough to actually melt the wire(s). I would search for the controlling fuse and try to trace it's termination. Perhaps it was previously bypassed? NOT GOOD

[AlohaBra]

Originally Posted by muley88

1996 Cherokee Country. When we turn on the heater/ac blower, the red wire coming into the ignition switch connector from the battery gets melting hot after a few minutes. This wire has a splice on it which replaces the part just before going into the connector, I suspect because it has melted before.

Seems like this would be a short somewhere. Ideas? Thanks.

This is a tough one, but a schematic is a good map to trace by:

Link to site, and look at Fig. 33. You can trace the red wire.

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

As far as blower motor or short (which is a misleading term: it means two wires crossing causing a short circuit--but people usually mean a short to ground which blows fuses), you will have to look at the wiring harness to see if it was wired wrong or damaged.

Does the blower motor had all the speeds or just high?

[muley88]

The red wire gets hot in relation to the blower speed. Speed 1 - not hot. Speed 2 - maybe warm. Speed 3 - getting hot. Speed 4 - hot. It gets hotter the longer the blower is on and we have insulation melting. It's as if the red wire is eventually feeding power to the blower motor instead of blower motor relays. At least I think there are relays. Need to get schematics.

Blower motor does operate on all speeds. Nothing fishy there as far as I can tell.

Thanks for the link to schematics, but they are cursory like the ones in the small Chilton's book we own. Maybe I can get full schematics at the library.

[AlohaBra]

You can try look at my set for the 2000 MY here:


http://jeep.larrynova.com/00/00_XJ_Wiring.pdf

[dave92cherokee]

I'd pull the dash trim pieces off and follow the wire as best you can. It sounds like either there was a problem in the past and they spliced it straight to the controls to make it work or another wire inside the dash has heated up and melted a spot on the red wire connecting the two causing them to short together and draw more current than the wire can handle. On my jeep someone rigged up the electric fan to a switch that was mounted on the dash and the wires were drawing to much current and melted the insulation thus resulting it in also burning through and melting about a dozen wires inside the dash and half a dozen in the engine compartment. To fix the damage when I bought it I had to completely remove the entire electrical system under the hood and the dash from the jeep to fix the wires and cover with heat shrink tubing to prevent shorts from happening.

[muley88]

Thanks for the suggestions from everyone. We disconnected the one terminal going into the connector to the ignition switch where the ignition switch was heating up (which is also the terminal supplying the heater blower) and measured current there and also at the fuse for the heater blower (after the ignition switch. The current was the same and only a little heating occurred, so that said the terminal itself going into the connector was the problem.

We went to a wrecking yard and got a terminal that matched the connector (instead of the hokey substitute terminal), soldered it in, and no more heating. A less than $1 fix. Nice.

I suspect that heating at that terminal occurred because of a previous blower motor that failed and drew too much current and melted some insulation on the wire at the connector. The electrical fix was poor.