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New-to-me 5.9 GC, some questions.

1K views 8 replies 5 participants last post by  leftfield6 
#1 ·
So i bought a used 5.9 Limited a few weeks ago, I knew it needed a VC, tires, few other things. So far, I've done the VC (not hard, glad I'm keeping the 249), new AC compressor, and new tires. Some things I haven't gotten to yet include replacing the sagging headliner, and replacing some blown speakers.

Before I get to those "nice to haves", I have some newly discovered issues to deal with.

  1. Charging system - after a few days of working fine, my charging systen seems to have fritzed out on me. Driving along today, all good, suddenly my volt gauge goes to ZERO, and "check battery" begins flashing on the VIC. Still running fine, as are all the electrical items like lights, e-fan, etc. I make it back home, about 10 miles, with no drama. Now, in the driveway, it will start up, gauge reads about 10 volts or so for a minute +/-, and then it drops to zero, and check battery message. I cleaned terminals, and checked cables, they look okay. Has my voltage regulator died? Alternator?
  2. Sunroof has stopped working. Worked fine for days, and then suddenly yesterday, no workee. Is there a fuse for the sunroof on the 98. Don't see one listed in the owners manual, and my repair manual is not here yet from the guy I bought it from.
  3. Mt wipers don't park. I know there is a thread/FAQ about the module behind the kick panel, but I wonder if this is connected to the sunroof. I saw in another thread that the interval wiper function and the sunroof share some circuitry or fuse. Thoughts?

Other than that, she's got a few things to work through. A little clunking coming from the back over speed bumps, needs new shocks for sure, she's bouncy! Couple of spots on the bumper where the clearcoat has failed. I'll be touching that up.
 
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#3 ·
for sunroof, from what i've heard (I don't have one) check the fuses, and then check the actual buttons themselves. Seems they get bad after a while and wont control the sunroof. Just be glad it's stuck closed lol
 
#5 ·
Thanks all. The only issue I'm working on right now (obviously) is the one that's keeping me off the road, and that is issue #1. (voltage issue)

So, today I went down to the local FLAPS and had them do the battery test. Battery tested fine. So, since it's so damn easy to do, I pulled the alternator right there in the parking lot and took it inside so they could mount in in their testing rig. Good news/bad news is that it tested perfect. Good news, because, hey, I don't need an alternator. Bad news, cause that means I move on to the next likely fail point. I guess it's the PCM now, right?
 
#6 ·
It could be the voltage regulator, but I would check all the other basics before you go that route.

Are the battery terminals clean and tight? All your grounds clean and tight including the engine strap ground?

Still sounds like the alternator is on it's way out.
 
#8 ·
Terminals are spotless and tight. Haven't checked the other grounds like engine strap but will do. The test rig at Advanced Auto does a pretty complete series of tests on the alternator and it tested out perfect. Guess it could be something in the alt, but the way the problem occurs makes me thnk it's something in the PCM.

Regulator is in the pcm,you can bypass it.there is some info on that on the dodge forum,google it
I checked into that. Good info here on this page ---> http://store.alternatorparts.com/hd-external-voltage-regulator-conversion-field-replacement-kit.aspx

Might consider that. Looks like a replacement PCM would set me back about $300 for the 5.9L. Versus the kit linked above that is $65. Hmmmm.
 
#9 ·
Pretty sure it's my PCM. Here's the new info on the symptoms/behaviors:

  • If I start the Jeep and the volt gauge jumps up to about 14, it will be fine until I turn the ignition off, no matter if I drive 1 mile or 10 miles.
  • If I start the Jeep, and the volt meter goes up to just a hair over 12, in less than half a mile, the volt gauge drops suddenly to zero concurrent with warning chimes and "Check Battery" on the VIC. Jeep will keep running, at least for a while. I really haven't pushed this too far. New thing to add here is that I plugged a cigarette lighter volt meter in, and watched it as the Jeep malfunctioned. In the case where it starts off barely above 12V, when the chimes/alarms/VIC go off, the voltage actually jumps to 13.7 or 13.8 volts, :dunno:

So, I've had the battery checked and it's good. Even swapped batteries with another vehicle, did the same exact thing. Alternator has been checked by a FLAPs, it passed perfectly. Took it to a dedicated auto electrical shop, they checked it and said it is fine, no problems.

Battery cables look fine, seem fine when I check them with a multimeter.

It's almost certainly the PCM at this point, doncha think??
 
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