I have the following intermittent issue with my 1999 Dodge Dakota 4x4 3.9L V6 (152,xxx miles)...

There seems to be a power surge that changes the battery gauge from normal (in the middle) to high then to low. As it surges to high, all my lights will brighten as if the high beams are on. The surge also makes the lights on my dash brighter too. If I have the windshield wipers on they will go crazy fast. If they surge gets to high my "check gauge" light will ding then my air bag light will trigger too. Now when it surges back, it will either go to normal or go to the low. During the surge to the low, everything stated above will do the opposite. It has now gotten to the point it has drained my battery to its death.
Again this is a very intermittent issue. I can start it up and the battery gauge is on the low side. I can start it up and be normal all day. It will surge at all MPH and when idling. Warm, cold it surges. The weather outside can be warm/cold, rain/sun and it surges.
On the Thursday, my truck finally died. I used my jump pack and got on jump with it but as soon as I let my foot off the gas it died. I got a jump with a big boy truck. It started but as I was giving it gas (30 sec) it dead. After that jump, the engine would not turn over, no click, click, click. I was only a few seconds down the street from my drive way. The big boy truck towed me back home.

Over the weekend I fixed...
I bought a new battery and did a warranty swap on my 3 year old alternator. Still surges. I replaced the starter (since it was the same age as the truck.) Still surges. I replaced the negative wire on the battery, original looked corroded and also the positive wire from the fuse box. I terminated the positive wire from the starter too. Still surges. I removed the fuse to the cigarette lighter since it’s always on (ash tray broke off years ago). Still surges. I found a dead fuse to the backup lights, replaced it... still surges. I used an ohm reader and checked about 90% of the fuses that I could. None were the issue. When I used the ohm reader, it would show I had a short, then minutes later the short was gone.


I have attached a picture that I took as I started it up on Thursday before it dead. The engine light is for my exhaust leak it’s the only code).

I'm planning on replacing the TPS today as well just to rule it out, even though my RPMs don’t jump.

Any other suggestions before I give it to a mechanic?????

 

How long has the check engine light been on?

It should throw a code. You'll need to get it read with a scan tool in '99. There is a battery temp sensor that helps regulate the charge, under the battery. The voltage regulator itself is in the PCM. Reading the code might help narrow down the problem.

Check the codes and make sure all connections are clean and tight.

 

Its wild guess but check all your relays feel them for high heat

Do a night time inspection of all you’re wiring for electrical arcing/visible sparking at night with no light these will be more visible if you know what I mean

 

00DakDan is probably correct Im guessing with electrical problems.

 

you might also inspect the wires that go to the alt. back to the PCM .Grounding the field is what makes it chage.