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Unread 08-23-2013, 12:07 PM   #1
GS41Sailor
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Weird electrical problems after evaporator replacement

I just finished replacing the ac evaporator and heater core in my new to me 97 XJ 4.0I6. after reassembling everything I have the weirdest electrical problem. None of the following works:

dash illumination
gauges
parking lights (front and rear)
side marker lights
turn signals
brake lights
backup lights
ac compressor (even when jumping the low pressure switch)
hazard flashers
Parking brake indicator lamp

When metering the voltage on the 12v accessory outlet the reading is 6.3v with the glove box door open, but when closed I read 12.3v. The 4wd and shifter lamps glow dimly with the glove box door open and extinguish when the glove compartment door is closed.

Has anyone had a similar problem? I am at wits end trying to locate the failure point. I have disconnected and cleaned (contact cleaner) all of the brick type plugs under the dash and all fuses check OK. What have I done wrong? Please help!

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Unread 08-23-2013, 03:25 PM   #2
AbkshelbyXJ
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Check all fuses first. Sounds like you have either damaged or not plugged in the body computer. Others will chime in with other ideas.
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Unread 08-23-2013, 04:04 PM   #3
GS41Sailor
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Thanks. Where is the computer located? Is it in the engine bay behind the left headlight? How can I test the computer? It is not throwing any codes.
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Unread 08-23-2013, 04:08 PM   #4
CJ7-Tim
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There is no body computer or Body Control Module (BCM) on the XJ Cherokee.


Quote:
Originally Posted by GS41Sailor View Post
....When metering the voltage on the 12v accessory outlet the reading is 6.3v with the glove box door open, but when closed I read 12.3v. The 4wd and shifter lamps glow dimly with the glove box door open and extinguish when the glove compartment door is closed.
From the symptoms it appears that you have damaged some wiring, or not fully connected a wire harness.

12v switching to 6.3v and back to 12v and lights illuminating without a good reason should make one suspect a short circuit, or possibly a disconnected ground wire.
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Unread 08-23-2013, 04:25 PM   #5
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Thanks CJ-7. How would I begin troubleshooting for a bad ground? I have carefully inspected each connector and each appears to be fully mated. No visible nicks or bad spots in the visible portions of the wires around the connectors.
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Unread 08-23-2013, 04:35 PM   #6
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Did you disconnect the main wire harness connector on the driver side firewall and remove the dash ?
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Unread 08-23-2013, 04:39 PM   #7
GS41Sailor
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Yes, if it is located on the transmission tunnel drivers side. I just swung the dash rearward on the passenger side
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Unread 08-23-2013, 05:01 PM   #8
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Make sure the main wire harness connectors are firmly plugged together, and then look at, and feel all the wire harness sub harnesses for damage. I would guess you put a screw through one or pinched one between the dash and the body.
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Unread 08-23-2013, 05:58 PM   #9
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OK. Will do that tomorrow if these darn rains will just let up a bit. Thanks again for the pointers. I will post the outcome after I take another verry close look.
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Unread 08-24-2013, 03:27 PM   #10
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Just got finished....again. Disconnected all connectors to the dash, swung the dash out, inspected all wiring, found nothing suspect. Reconnected all connectors ensuring that they are well seated, hung the dash on the two studs below the windshield, reconnected the neg. battery cable, turned the ign. sw. to run and lo and behold the gauges came up! No turn sigs. or flashers unless you hold the button on the glove box in. Hold it in and turn sigs and flasher works. Turn on the headlights and all gauges go to 0, both turn sig. arrows light up and the airbag light comes on. Turn off the headlights all goes back to normal. What do I check now? Headlight switch maybe? Everything worked great before I took the dash out. The rest of the project was easy except for this electrical garbage!!! Help!!!
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Unread 08-24-2013, 05:24 PM   #11
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Failure of the headlight switch is somewhat common. The symptoms described do not bring to my mind any failure of a specific part, which kinda sucks for you.

IDK why the glove box switch would cause all that, but you could disconnect it, or temporarily relocate it/tape it up so it stays in the off position.
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Unread 08-24-2013, 06:32 PM   #12
GS41Sailor
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Thanks cj-7-Tim. A trip to Advance tomorrow for a new switch and maybe that will do it. I'll post the result. Thank you for the help and support.
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Unread 08-27-2013, 04:16 PM   #13
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Well, after installing a new headlight switch, a new gremlin has appeared. When turning the headlight switch to the extreme ccw position (to turn on the dome lights) dash indicates OK but dome lights do not light. Open the door and the dome lights light. If you rotate the HL sw. cw past the click, both turn signal arrows light and all gauges go to 0. Any suggestions where to look next? Does anyone have any wiring drawings showing grounding points or connector configurations? I have a Haynes but It is not really much help.

Last edited by GS41Sailor; 08-27-2013 at 04:29 PM..
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Unread 08-27-2013, 07:03 PM   #14
CJ7-Tim
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Once you go past brake jobs and oil changes, Haynes and Chiltons are worthless.

Check here-
http://www.pacificcoastmanuals.com/
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Unread 08-27-2013, 07:31 PM   #15
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There are two (multiwire) ground points under, and attached to the dash structure. One on the far right side to the right of the glove box and one to the far left side to the left of the steering column. These may have been distrubed during the dash removal/install. Check the one near the glove box first.
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