XJ - Light switch/turn signal/radio/engine electrical issue

[87Warrior]

This evening I returned from a quick ski trip to Steamboat Springs, Colorado. Snow was nice, but not enough. Weather was fantastic for skiing all day. Naturally we took the XJ on the 10 hour drive. Unnaturally we had some issues.

 

Quick history of the Jeep

Purchased the 1993, 4.0L, 2door, Sport, with 70K miles 5 years ago from a neighbor who moved here from Denver. He said the only thing they did to the Jeep was have AC installed and had a Tape deck put in. The AC system looks very factory, so we assume it was a Mopar kit and dealer installed. Ever since we have owned the XJ it had a few annoying issues. The Radio could not pick up many FM stations and the Blower motor would kick on if the key was turned back to ACC. (is this normal for the XJ/MJ?) The radio would also quit transmitting sound randomly; summed it up as an old radio. We installed a Mopar cruise control kit 4 years ago, very easy and straight forward. A few weeks back I pulled the tape deck from the XJ and installed the CD player that was in the MJ. Plugged right in and worked great. Perfect, tunes for road trips

 

The issue

After 6.5 hours of driving we made it to Denver, CO. Needing to switch lanes I press the blinker right to make a safe lane transition. When I pressed the stalk, the radio shut off for a split second and resumed playing. Nobody else noticed so I figured I was loosing my mind. Made it through the city and started up the long strech of I70 to the tunnel. Had cruise set at 65mph, transmission in "D". We start driving into some fog so I decide to kick the head light on. Pulled the switch and the radio turns off completely AND the engine looses all power, like the key was turned off. A 1/2 second later the Jeep is resuming to the set 65mph. We continue on to the 'Boat without issue and a record 24mpg on 85 octane.

 

Head to downtown that night for some dinner. Drive the XJ, park, eat, and return to the Jeep. The radio does not come on. No big deal, the hotel is just a few minutes down the road. I hit the left blinker and nothing happened. Pull up, repeat, and the signal flashes.

 

Go skiing and don't give the XJ much thought. Sure, the radio did not fire up when headed to the slopes in the morning, but I was more focused on the edging my skis received. Dinner time rolls back around we head back to downtown. Now when the turn signals are activated they do a 'fast flash' like LED's have been installed. I check the bulbs and they are functioning properly.

 

I wind up at NAPA to buy some wire, electrical tape, and a fuse holder to at least get the radio working for the 10 hour drive home. Snipped the 'Switched ACC' power wire from the radio and tapped it to the cigar lighter to see if it would fire up. Nothing. Patched the wire then sniped the 'Constant Power from Batt' wire and tapped into the cigar lighter. Presto, the radio kicks on but losses all settings when the key is switched off because the cigar lighter is switched. Button everything up to make sure there are no short possibilities. At this point the turn signals flash at a slightly faster than normal speed, but much slower than a 'fast flash'.

 

Drive home with this set up and encounter no problems. Only squeezed out 21mpg on the 85 octane due to strong crosswinds.

 

Cliff notes

- 1993, 4.0L, 2door, Sport, 117K

- Used the blinker and the radio briefly shut off

- Pulled the headlight switch and lost the radio and engine power (like the key was turned off) for a brief second

- Radio refuses to come on; no lights, no-nothin'

- Blinkers experience 'No Flash' and 'Fast Flash'

- Removed the 'Constant Power from Battery' wire from the radio harness and tapped into the cigar lighter. Radio works.

- 21mpg and 24mpg bests in the XJ with 3 adults and skis up top

 

How in the world should I try to diagnose this? I can read and understand wiring diagrams and am comfortable with a multimeter, but I cannot even figure out where to look or what to test. Any direction is much appreciated :yes:

[64 Cheyenne]

Grounding issues can cause some of the problems if not all of your issues. I'd check battery cables, block to firewall connections etc.

[JeepcoMJ]

remove your rear hatch "door" panel. on the left side of the hatch (driver's side, there is a black single pin female wire, and a blue 2 wire single pin wire. if they are plugged together, you have power to ground...that can and will cause your issues. unplug them.