Sanity check: '96 XJ intermittent short tracing - JeepForum.com

 
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post #1 of 4 Old 09-28-2013, 04:35 PM Thread Starter
mjbraun
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1996 XJ Cherokee 
 
Join Date: Sep 2013
Location: Chicago
Posts: 5
Sanity check: '96 XJ intermittent short tracing

My 1996 XJ 4.0 has, for many years, had a problem with the power door locks where the M13 fuse (20A) would blow and the locks would cease to function. Both driver and passenger side switches work and I can hear the relays operating, but the solenoids aren't being triggered.

Mechanics have given up trying to isolate the problem (and I gave up replacing fuses), but I thought I'd give it a go tracing out the probable short. A spanner in the works is that the fuse doesn't blow immediately on use, but rather some time up to a week after, which makes me think it might be a worn cable intermittently shorting out on the chassis somewhere while the vehicle is in motion.

Looking at this Autozone Wiring Diagram #31 I see the only wire shared between both lock/unlock relays is the "LT GRN" straight to the fuse. Would I be correct in replacing that wire with new connectors and 14-gauge AWG (as per SirGCal's post here) wire as an initial repair step?

In my Haynes manual, I see splice R6 / 99 20BK (I assume that means 20 amp, black, so probably ground) as being a related cable, so I'm not sure if that might also be a place to swap out.

Thank you!


Last edited by mjbraun; 09-28-2013 at 04:56 PM. Reason: Additional data
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post #2 of 4 Old 09-28-2013, 05:05 PM
JWELK
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1999 XJ Cherokee 
 
Join Date: Apr 2011
Location: Ceiba
Posts: 910
Yes, but you don't need to increase the wire size. Before you replace the wire, I would pull either the lock or unlock relay to see which circuit has the short. As they both supply 12 volts continuously, either could have the short. If, after pulling each relay, then both relays to verify, and then finding the fuse still blows, you know it is the Lt/Gn wire. Otherwise the short is in one of the branch circuits. The driver door is usually the culprit, as it gets used the most. Of course if the car has been damaged, then look in that area.
Let us know,

Regards.

Jim W
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post #3 of 4 Old 09-30-2013, 09:12 AM Thread Starter
mjbraun
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1996 XJ Cherokee 
 
Join Date: Sep 2013
Location: Chicago
Posts: 5
Jim,

Thank you for your response: I hadn't considered that the branch circuits could be involved. I recently replaced the driver door switch assembly (the driver window switch was janky) and that may have eliminated the problem if that was the cause. But I'm going to pull one of the relays and give it a go. The car hasn't had any accidents so it's probably not a damaged component, so I'm pretty sure that the relay pulling diagnostic "sequence" you suggested will help me better narrow down the source of the short.

Much obliged!
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post #4 of 4 Old 10-01-2013, 10:08 AM
JWELK
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1999 XJ Cherokee 
 
Join Date: Apr 2011
Location: Ceiba
Posts: 910
My pass side regulator broke, I took off the panel and the switches and discovered that none of the door locks work. That means the door locks are wired in series and a short in any of them will blow the fuse.
Let us know

Jim
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fuses , power door locks , wiring

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