Ex has a 99 WJ, 4.7 Limited.
Aside from her coolant leak(sounds like radiator), she said her computer shut down 5 mins after telling her she had a coolant leak. She said it took awhile to come back/reset, during which time she had zero power. No lights, no nothing and couldnt even lock/unlock doors.
Finally when it rebooted, or reset, all of the gauges went wild and power came back.
Any ideas on the problem ?

Thanks.

 

When I blew the upper radiator hose in my 99 (while driving, dontcha know), it never threw a code or console warning at me at all.

I also had the electrical problem you describe and it ended up being a badly intermittent battery cable clamp. One of the many times I went in to screw with it, the shock of going up and down as it made and broke connection fried my alternator diodes. Just popped 'em. Once I went in with a post brush and some baking soda water I was able to get a permanent grip on it with the clamp. No issues since...though I did end up replacing the alternator!

 

OK, so you're thinking it may not be anything with the computer?
She's at work about an hour away so I can have her get that checked. (post connection and alternator). I'm wondering if maybe water got on electrical parts.
Thanks, GCWJ

 

The radiator hoses and the battery are clear across the engine bay from each other so I would assume they are unrelated problems.

​​​​​​An intermittent battery connection can kill the alternator. Obviously, only replace that if it's bad! What I mean to say is to grab a cheap battery post brush and some post cleaner on your way over. That could be all that it is. Tighten the clamp *good* and wait to see if she has any more issues.

 

Cool. Thanks.

 

the PCM will shut down if it doesn't have a constant supply of 12 volts. When the power becomes intermittent, it shuts down to protect itself from voltage spikes. Hopefully, this happens before anything gets fried. Wild swings of the gauges is a warning. They are not directly connected to the sensors like they used to be, but receive their information from the PCM. This is part of the digital bus system used in the WJ models.

 

NAILED It!

The only thing you need to buy today is a battery terminal cleaning brush. Pop off both, scrub them both to shiny, and be happy. The alternator is likely fine.

 

Are the WJ with the 4.7 V8 known to have battery cables/connectors that fail over time, need to be replaced?
I have an 04 with issues

 

Not just jeeps, but ALL vehicles with top post batteries and molded lead terminals have this problem! This is made more serious by poor maintenance.