Complete Electrical Failure

All started about three weeks ago. I was headed out of town on a 3 hour trip, got around the corner from where I left and looked down to see my volt meter pegged to 19 and the check gauges light on. Pulled over and re-started the Jeep, problem solved. No more issues until about a week and a half ago. Started having some cool/cold starting problems. Jeep would crank fine, and as soon as it caught it tried to cut back off...really low idle. It never did stall, and after about 5-10 seconds it picked itself up and all was well. Didn't do this every cool/cold start...maybe half the time.

Well tonight I go to run some errands, after driving it this morning with no issues. I start the Jeep, and as soon as it fires it runs for a fraction of a second and stalls right back out. At this point the instrument panel and everything else electrical went dead. No lights, no radio, no gauges...nothing. I try to turn the ignition back on again and still nothing. What I did notice was while the ignition was in the OFF position, the radio would come on about 1/4 power and flicker. When the ignition was in the ON position, the radio would go OFF and the brake light would very faintly come on (my e-brake was on). A little ass-backwards no? Opening the door would kill everything (or what little bit I actually had).

I got out of the Jeep and was going to get my tools out of the back to unhook the battery and see if that did anything. I get out and happen to glance back in to see my dome light come on and everything come back to life. Turned the ignition on, dash lit up like normal, I noticed my radio presets were gone and my trip-meter had reset. Tried to crank the Jeep and it wouldn't fire...just sit there and crank, so I knew the computer lost it's memory and eventually the idle would come back, with some help (been down that road before when i've had batteries go flat on me before).

After about 5 minutes the idle was back and everything was good to go. Drove around for a couple of hours since and all is well. The true test will be tomorrow morning once it's had a chance to settle down.

All my battery connections are relatively new (less than 1 year) and pretty much spotless. All my cables were upgraded by myself and a friend to 2 and 4 gauge (welding cable actually). If it acts up again in the morning i'll be cleaning my connections just to be safe.

In case you've never had to get a late model XJ (or vehicle for that matter) going when the computer doesn't have a memory, it goes about like this:

http://www.youtube.com/watch?v=Q5OyrakCNBw

I tried to get a video of the radio spazzing out, but there wasn't enough light for my camera to pick it up on my phone.

Anybody been down this particular road before? I'm all ears to suggestions!

I would start with the main grounds. Check clean and tighten them. BigAlpha recently had a similar problem if I recall and his was a short in his tow light box, it was all melted and wires were crossing. Just start running through it little by little and check for bad connections as you go along and check for bad grounds and crossed wires. If you want I can give you a hand with it anytime after Easter weekend.

I'll let you know what's up dude, thanks for the offer. I've got a car i'm going to work on tomorrow (hopefully for a profit this time!)..so we'll see if it does it again any in the morning.

I'll probably clean at least the terminals tomorrow just to eliminate that. If that doesn't help, then let the fun of tracing wires begin!

X2 on the grounds. I forget all the technical names, but basically, there is a little "woven" cable that hooks your firewall to the back of the motor block. This wears, and loses good connection. Replace this cable.

What happens when the vehicle completely dies, it resets a computer that monitors idle and throttle position. With the bad connection, the voltage changes, and the computer thinks the throttle is too open, so it backs it off, causing it to stall out. Once it warms completely up, it will be all OK again, until next drain.

I had that much of your same problem and for proof of concept (before actually making a repair) I took a 10awg wire and held it to the neg batt post, and to a cleaned area of the intake manifold. Started after a drain, and fired up with no problems. So, now I have a fix on the list!

As to your other shorts... I dunno. Search around on here. I have read some threads kinda similar. Good luck!

X3. Start with grounds. I believe dipstick and back of head to firewall are the main ones, probably one off the neg post of the battery. Actually disconnect, freshen them until shiny before reattaching.

Thanks for the suggestions guys. All cables, including grounds, were replaced less than one year ago with 2 and 4ga wire by myself and a friend of mine. I'm going to start with the battery and work my way back from there. Even though the connections appear to be clean and making a good contact, electrical work has taught me that often times it's not enough.

Not the first time i've had the computer go flat on me and lose it's idle...had a number of flat batteries in the past.

If it ends up not being grounds, try refreshing the bulkhead connector. I may just be biased towards this as it's the latest "jeep goes completely dead and randomly decides when it's going to work" root cause I've seen, but tweaking some of the pins in one on the trail revived a jeep long enough to get it off the trail and home to where it could be properly cleaned with CRC contact cleaner and refilled with new dielectric grease. If a 97+ is anything like a 96- you will need a quarter inch socket wrench and plenty of patience.

Definitely worth a shot! I did check to make sure the connections were completely in, and they were.

What's the ground like to the computer? Maybe there's an abraded wire someplace.

kastein said:

If it ends up not being grounds, try refreshing the bulkhead connector. I may just be biased towards this as it's the latest "jeep goes completely dead and randomly decides when it's going to work" root cause I've seen, but tweaking some of the pins in one on the trail revived a jeep long enough to get it off the trail and home to where it could be properly cleaned with CRC contact cleaner and refilled with new dielectric grease. If a 97+ is anything like a 96- you will need a quarter inch socket wrench and plenty of patience.

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x2

Driving home one night from work and the jeep shut off completely. No power to anything in the interior, but the headlights and the hazards still worked. It started after I pulled over.

2 days later, driving home from lowes, hit a bump and the jeep shut off. Had to tow it back to the house. Completely tore apart the dash, etc and was about to give up. I leaned on the bulkhead connector and the radio came on.

Took it apart, cleaned the gunk out of it and put it back in and it's been fine ever since.

I"ll give the computer a look over tomorrow if I have time...spent all morning afternoon working on a Pontiac that was an epic fail, then 4 hours at work tonight fixing other cars...Been running around in the Jeep all day today with zero issues.

Loved that video...reminded me of my own adventure LOL
Did you mention your alternator? Have you had it checked?

Lots of different circuits in any vehicle, but they fall under two general categories: switched and un-switched.

Do your headlights, interior lights disappear--then you have main power issues as they are un-switched circuits protected by fusible links or maxi-fuses. If only the switched circuits--radio, ignition, HVAC are effected then the problem is more likely fuse panel/PDC, grounds, ignition switch related.

Battery, starter, and alternator all checked good. I was on my way to work that night anyways, so I ran a test on it when I got there. The battery is less than 1.5 years old, and the alternator is coming up on 2 years old this summer (brand new alt, not a reman).

Didn't get a chance to check anything today..spent the better part of 8-10 hours doing an evap/heater core replacement on another XJ. Been driving mine for the last 2 days and you can't even tell it ever did anything wrong.

I hate electrical issues! So far i've been quite lucky on my Jeep..this is the first time i've had a problem like this that wasn't a result of a bad connection at the battery.

I had a similar problem at one time

I was grounding out on my exhaust manifold, the heat melted the insulation and the bare wire was grounding right on it.

Would only do it if the stars aligned and wouldnt start until the wire came of the manifold. Worth a check

It's an electrical fault... The only reliable way of reproducing the failure is to be late to something very important. I suggest filling your schedule with important meetings, you will find plenty of time to debug it

kastein said:

It's an electrical fault... The only reliable way of reproducing the failure is to be late to something very important. I suggest filling your schedule with important meetings, you will find plenty of time to debug it

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Hahaha..very important meetings or late for work usually brings out the best in bad karma (vehicle problems, excessive traffic, and of course getting stuck at all of the 20 traffic lights between you and your destination).