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Unread 08-09-2013, 10:09 PM   #1
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
Electrical problems after heater core replacement

Hey all,

Vehicle: 2000 XJ 4.0, 4x4, Sport.

So I completed the heater core replacement job, and also replaced the evaporator while I was in there. Re-installed the dash and am getting pull-my-hair-out electrical issues. The only issue that was present prior to doing the work is fault code P0135. The jeep starts and runs fine, but here's what's happening:

1. Rear defroster switches off immediately after pressing the switch. It should, as I recall, stay on for a short period of time before shutting itself off.

2. Starts and runs fine, but when the headlight switch is pulled out, the tachometer is intermittent, the rear defroster switch lights up solid, the rear window wiper runs constantly.

3. Fault codes P1694 and P0135 are present.

I've double checked all connections, and have found no visibly damaged wires or connectors. I have had trouble figuring out how the dashboard grounds to the chassis. I have a section of wire with alligator clips, and I connected a bare portion of the dash directly to the battery negative cable, still have same problems. I thought that maybe the alligator clips didn't provide enough contact, so I made a much better ground cable that I will connect sometime soon. I spent 5 hours on this thing today, and have thrown the towel in for the night.

It's probably a longshot that anyone has experienced similar problems, but any advice will be appreciated.

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Unread 08-09-2013, 10:24 PM   #2
wgirvine
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1992 XJ Cherokee 
 
Join Date: Oct 2007
Location: Rosamond, CA
Posts: 602
Somewhere, you are missing a ground.
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Unread 08-09-2013, 10:39 PM   #3
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
That's what I'm thinking and hoping. The old cliche "sounds like a bad ground" haha. Do you know how the dash is supposed to be grounded? Does the dash frame complete the ground, or does the wiring? What leads me to believe that the dash frame is responsible for completing the ground is that there are a few areas on the dash frame where ground wires are terminated.
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Unread 08-10-2013, 10:47 PM   #4
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
Well, I put everything back together, including a dedicated chassis ground and still have the same problems. I did find a couple bare wires on the harness leading to the ignition switch, however. Both wires read 12.08V. If they are both hot, can they still cause some kind of short if they touch? The jeep used to have an alarm system on it.




Can anyone identify this black electrical connector?

It's located along the steering column, and I don't have a clue where it is supposed to connect to.

Hoping to figure this thing out because I sunk $500 in parts for the heater core, evaporator, water pump, radiator, etc.
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Unread 08-10-2013, 10:50 PM   #5
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
One more thing:

It's throwing two codes now, P1698, P1694. Both pertaining to the transmission control module. I'm wondering if the TCM shorted out cuz of the bare wires I found, but scratching my head as to why it has the issues listed above pertaining to pulling the headlight switch and having the rear wiper turn on!
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Unread 08-11-2013, 02:55 PM   #6
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
TCM swapped with junkyard TCM, and same issues persist.
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Unread 09-03-2013, 07:00 PM   #7
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
UPDATE:

Problem was a bad ground. Even thought I ran a dedicated ground from the dash frame to the firewall, it was on the driver's side. Apparently that metal framework doesn't connect with the passenger side dash frame. I had a sheared off mounting bolt, and that was causing my open ground.
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Unread 09-03-2013, 10:44 PM   #8
tamnoz
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2001 XJ Cherokee 
 
Join Date: Apr 2006
Posts: 59
bad ground

I do about 50-60 Chrysler products heater/evap jobs a year and I was ready to tell you bad factory ground. Been there.
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Unread 09-03-2013, 10:52 PM   #9
Uhoh429
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2000 XJ Cherokee 
 
Join Date: Jul 2009
Location: Chicago
Posts: 21
Yeah, I own a jeep and a chrysler town and country. For the most part, I think they're well made vehicles, but there have been a few instances where I say to myself, "Really!? Why would anyone produce this" every manufacturer has its problems.
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