Yesturday, about two hours from home on a six-hour drive, the Generator light came on and the volt meter went from around 14.5 to just above 12 V (approx). The temperature gauge never fluctuated--indicating the belt had not broken. I pulled off at the next exit to find no obvious problems. There was an Auto Zone close by, so I had the alternator tested--it's fine.

Proceeded on, as the AutoZone tech and I both agreeded that there would be no one to fix it until Monday. Made it back home, using lights conservatively for only the last 1/2 hour of the drive, as dusk was settling in. As I used lights, the voltmeter dropped slowly until it was just above "8" volts as I pulled into the driveway. Whew, made it home, that's it.

Today, I found one battery at around 11V, and the other at about 9.5 with the flukemeter. Any hints of further steps to take? I plan to jump it tomorrow and take it to DJ's auto and truck in Naperville, I have few electrical skills. I purchased the batteries from Sam's in Sept '02 and they have a three year warranty. They offered to replace them if defective when I called them. Anyone else have any ideas of things to check for? Thanks in advance for the help.

 

Sorry, I guess it's in the signature line, but my truck is a '96 2wd with the 12 valve engine and a five speed. About 281k miles. Thanks

 

Could be that one of your sensors on the engine went south... I had the Crank Position Sensor on my 92 crap out and I lost my alternator too... Luckily it was just a bad connection that was easy enough to fix. Hope this helps,
Good luck.

 

Have you looked at the charging system fuse in the pdc?- and the contacts on hte alternator?

I'd disconnect both batteries(engine stopped, key off) and would measure voltage on them again, charge them separately if possible, and see whether one or both do respond to charging. (Or show signs of being defective)
I'd also try a known good battery (or two) to verify the charging system.(after going for the fuses and contacts)

HTH

AlpineRAM

 

Thaks for the info, the fuses look fine, the contacts are okay, have not changed anyway.

Many newer cars have a battery fuse as well, in case one goofs hooking up for a jump start.

 

don't check fuses with you eyes... They do crack and disconnect always use a DVM to test them.

Well a charging system is simple either voltage regulator or alternator. The alternator tested good then the next step is to check the voltage regulator.

 

I don't know for the 96, but on the 97 there is one big fuse in the pdc, where the red cable from the alternator enters it. (Towards the engine)
You can check it with a DMM.

HTH

AlpineRAM

 

you cant be charging. the batteries will read low because they are in a state of discharge. the regulator is in the pcm. i would get the alternator to a repair shop. it most likely has the brushes worn out. check for battery voltage at the alternator terminal. you have 2 smaller wires. one is 12 keyed and the other is a varible to ground controlled by the regulator. you can disconnect both small wires from the alternator. use an ohm meter and test the two small terminals. if its open it has a brush or rotor problem.

 

hi 96 12V

I have a 98 12V, and if it's the same, there is a relay in the fuse box that controls supples 12V to the field (the PCM controls the ground to regulate). The relay is controled by the PCM and will not close until the PCM senses engine rotation above crank speed (ie:it's running)

So, it could be the relay (same as horn, you can try swapping) or just bypass the realy and use a jumper between the Common and Normally Open contact, with this you will have 12Volt to the field (you can measure this at the bottom terminal of the the small feed wires at the alternator)

If all the wiring checks out, the regulator in the PCM could be toast. Some members here have put an external 1 wire reulator on to avoid the high cost of a new pcm, if you do a search here you can find them.

I had the same thing happen and drained my batts to 8Volts, I recharged with a charger and they managed to hold the charge again .

Good luck

 

By the way, the realy to the above post is the ASD relay, just remembered

It's alittle early here and my coffee has not kicked in yet

 

Well, the truck started without a jump this morning--and the voltmeter jumped right back to 14.5 as normal. Drove out to DJ's auto & truck, a 30-minuite drive, no change. Tried A/C & lights on, no change. They checked it all out including the alternator and voltage regulator--all fine. Cleaned and re-connected the cables, all looks well. No problems since, but I'll be watching that voltmeter more now.

What they did find--front driver's side caliper was hanging up, it's been pulling a bit on braking for a while. New calipers, rotors, and pads for the front--$680. Only $110 labor, the rest for parts. Actually not bad, last time I tried looking into doing it myself and Carquest & Dodge both wanted $129/each for new rotors. Word of warning to the new or those looking for a truck of this type--brake work is costly (lot of weight here) and there is not a cheap alternative. Also, I only got about 40k on a set of rotors--anyone else make more than that?

Thanks for all your input!!