From the FSM...
The voltmeter gives an indication of the electrical
system voltage. The instrument cluster circuitry controls
the gauge pointer position. The instrument cluster
circuitry calculates the proper gauge pointer
position based upon a system voltage message
received from the Powertrain Control Module (PCM)
on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the electrical system
and internal programming to decide what system
voltage message is required. The PCM then sends
the proper message to the instrument cluster on the
CCD data bus.
Refer to Group 14 - Fuel System for more information
on the PCM. Refer to Group 8C - Charging System
for more information on charging system
components and diagnosis.
Are you sure your ignition switch is good? It's pretty simple to check the voltage drop on it.
Well I think I may have narrowed it down to 2 wires. Either the main Starter wire, or the wire going to the Transmission, but I did an continuity test and the both show find, yet if I move them when the system is not working, the alternator begins to charge almost right away. I removed all the sheathing from the wiring harness in the remote area of the charging system. Getting somewhere... I think? LOL!!
Sometimes you can only find it when the system is under load. Start the vehicle, put your meter on the closest scale above 12 volts. Touch the red lead on the end closest to the battery of cable/wire being tested. Touch the black lead to the other end of the cable at its next termination. If you read anything above 1/2 volt, either clean the connection or replace the cable/wire.
What you are reading is the voltage drop. Difference in potential from point A to point B.
You can have one strand of wire making continuity, but it won't carry the load.
Well I feel like a real dumba$$ now. All along, it turned out to be the alternator. It was just fluke that it tested out good when I had it removed at the auto store 3 times. As it turns out the bad connection was really where the generator force drive wires go, but the damage was internal. I finally changed the alt and everything is fine. So I greatly thanks you for all your help. You've been a great help!!!
I have this same exact problem... I haven't done anything to it yet to diagnose... But I'm sure others have. Is it usually the alternator causing this problem?? I'd hate to buy one and find out its not the issue.
1998 Wrangler Sport w/ 5.2L 318 Swap
1998 Grand Cherokee 5.9 Limited - Kolak Ignition upgrade, K&N CAI, DT Headers w 3" Kolak exhaust/Flowmaster 50/Magnaflow CAT, Front/Rear Baer Drilled/Slotted Rotors, Front/Rear EBC Greenstuff Pads, Alpine CD/MP3/iPod Control Deck, RF 6.5 Power Series Separates
I know this thread is old. But I had a recent issue like this with my SO's 98 Jeep Grand Cherokee Laredo. (Lights dimmed, almost died) She was in a pinch and took the Jeep to a shop. (They mostly deal with electrical issues. Hence the name: Golden Electric) Was told the alternator was "shot." So they replaced the alternator with a "Brand New" one. Grand total: $169. She drove it home and had no issues. She went to pick our son up from wrestling practice and it started dying again. So back in the shop it went. They claimed it was the computer and that it was gonna cost her a lot of money. After being in the shop for another 4 hours they finally found the problem. A bad/loose ground wire! That's all it was!
So for anybody who has this problem in the future, just check the ground. Hope this helps!