98 Jeep Grand charging problem

da-moocher · 09-14-2007, 06:12 AM

Battery checks at 12.80v off, start jeep and now across battery 12.10v so I know its not charging, checked ground to large red wire on the back of alltinator and I read 28. volts.
regulator is built in to the PCM , jeep console says check battery and gauges and the charge gauge goes to o after 5 min of running

**Midnight Tech** · 09-14-2007, 09:16 PM

Bad news - time to replace PCM. Whoever had the bright idea to put the regulator in the PCM and not as a separate part should be made to pay for every Chrysler PCM replacement when it dies.

**qldit** · 09-14-2007, 11:45 PM

Good Afternoon Gentlemen, what is that circuit config MT, doesn't the large wire on those machines go directly from the alternator to the battery?

28 volts at the output terminal sounds a bit on the high side, in a conventional system that would almost suggest that wire circuit to the battery is open circuit.

I am out of touch with a lot of those vehicles, we don't have many here.

Cheers, qldit.

da-moocher · 09-15-2007, 01:57 AM

Thanks for the input on my output. The problem was the large red wire, traced it with ohm meter from the altinator to the fuse box, the end crimped contact to fuse box was not making contact, crimped and solderd and now I'm back to 14.5volts across battery and charging.

Thanks
Dave

**qldit** · 09-15-2007, 02:29 AM

Good Evening da-moocher, well done old chap!

Normally there are no fuses in that line, it just goes straight to the battery.

With all those crimped connectors in that circuit make sure you solder them, those crimps alone generate degraded connections and heat finishes them off!

That is a common kind of problem where the crimps are poor, it can sometimes cause localised heating at the nut connection on the alternator and affect the through bolt insulation and overheat the diodes inside.

Give those connections special attention and if the wire is discoloured or "cooked" in that area, replace it entirely and use new fresh lugs. (soldered!)

14.5 volts across the battery sounds pretty decent, keep your eye on it and if it gets any higher than that it may dissipate of water from the battery. (mainly through heat)
Nominally 14.4 maximum is ideal for a 1240 / 1250 SG battery.
Check the battery fluid level, add distilled water if neccessary to the bottom of the split rings.

Cheers, qldit.

09-14-2007, 06:12 AM	#1 (permalink)
da-moocher Registered User Join Date: Sep 2007 Posts: 2 OS: xp	98 Jeep Grand charging problem Battery checks at 12.80v off, start jeep and now across battery 12.10v so I know its not charging, checked ground to large red wire on the back of alltinator and I read 28. volts. regulator is built in to the PCM , jeep console says check battery and gauges and the charge gauge goes to o after 5 min of running

09-14-2007, 09:16 PM	#2 (permalink)
Midnight Tech Admin/Head GreaseMonkey/Igor's alter ego/Grand Exalted PoohBah Join Date: Dec 2001 Location: SC Posts: 2,921 OS: Windows XP Home/Pro SP3/Windows 98SE/Fedora Core 6/RH 7.2 with Autopoint/TAMS II	Re: 98 Jeep Grand charging problem Bad news - time to replace PCM. Whoever had the bright idea to put the regulator in the PCM and not as a separate part should be made to pay for every Chrysler PCM replacement when it dies. __________________ Please post all questions in the appropriate forum. Questions sent by email or PM will not be answered. Sharing my life...with my Imzadi! Interested in Trek gaming? Check out the Dynaverse! Proud supporter of the Carolinas Aviation Museum. If we have helped you in any way, please donate to keep TSF up and running!

09-14-2007, 11:45 PM	#3 (permalink)
qldit TSF Gearhead Join Date: Mar 2007 Location: Brisbane Australia. Posts: 592 OS: All Systems, mainly Linux	Re: 98 Jeep Grand charging problem Good Afternoon Gentlemen, what is that circuit config MT, doesn't the large wire on those machines go directly from the alternator to the battery? 28 volts at the output terminal sounds a bit on the high side, in a conventional system that would almost suggest that wire circuit to the battery is open circuit. I am out of touch with a lot of those vehicles, we don't have many here. Cheers, qldit.

09-15-2007, 01:57 AM	#4 (permalink)
da-moocher Registered User Join Date: Sep 2007 Posts: 2 OS: xp	Re: 98 Jeep Grand charging problem Thanks for the input on my output. The problem was the large red wire, traced it with ohm meter from the altinator to the fuse box, the end crimped contact to fuse box was not making contact, crimped and solderd and now I'm back to 14.5volts across battery and charging. Thanks Dave

09-15-2007, 02:29 AM	#5 (permalink)
qldit TSF Gearhead Join Date: Mar 2007 Location: Brisbane Australia. Posts: 592 OS: All Systems, mainly Linux	Re: 98 Jeep Grand charging problem Good Evening da-moocher, well done old chap! Normally there are no fuses in that line, it just goes straight to the battery. With all those crimped connectors in that circuit make sure you solder them, those crimps alone generate degraded connections and heat finishes them off! That is a common kind of problem where the crimps are poor, it can sometimes cause localised heating at the nut connection on the alternator and affect the through bolt insulation and overheat the diodes inside. Give those connections special attention and if the wire is discoloured or "cooked" in that area, replace it entirely and use new fresh lugs. (soldered!) 14.5 volts across the battery sounds pretty decent, keep your eye on it and if it gets any higher than that it may dissipate of water from the battery. (mainly through heat) Nominally 14.4 maximum is ideal for a 1240 / 1250 SG battery. Check the battery fluid level, add distilled water if neccessary to the bottom of the split rings. Cheers, qldit. Last edited by qldit; 09-15-2007 at 02:41 AM.