2000 Durango with just over 100k started acting stupid a couple of weeks ago. Running at 45mph, all the idiot lights came on like the key had been turned off and on. The engine never missed a beat. It did this a few times. I took the battery in, and it tested out fine. Took the alternator in, and it was only putting out 8-9 volts. Replaced the alternator. All seemed ok for a few days, then the Check Guages light came on. The charge guage had bottomed out, but came back up. I connected my ScanGuage. No computer codes, and it was running around 13.5 volts. This last thing keeps happening. Sitting at idle, I can watch the volts slowly drop below 12, down to 9, the check light comes on, and if I don't do anything, the voltage comes back up to 12.5 - 13. The day after I replaced the alternator, I was driving at night with headlights and a/c on. It stayed at 14.1 for the 10 mile trip through town. That's the only time I've seen 14 volts from this alternator.
So, is this a bad alternator, or am I in for some more fun?

Thanks to anyone who can give me some suggestions...

Jack

 

Replace the battery and replace the alternator and check all connections are clean.


If one goes out it usually means the other is going as well if it didn't start the issue in the first place. My experience says if you do one then do the other.


Let me recommend Auto Zone Duralast Gold series battery and also NEW Duralast Alternators. Whatever brand you chose, do NOT get rebuilt alternators and ensure you get and retain the receipt a life time warranty.

The Gold Series has a 8 year warranty.

 

It is probably a bad connection. Clean your battery cable terminals, posts, and make sure the battery cable to the alternator is tight.

 

i have to say diehard gold cuz i work at sears

 

Your a Sears boy rebel?

 

Here's an update. Replaced the alternator and battery. The first time I try to start it, it starts and dies immediately. If I don't touch the gas, it will just crank. I held it at about 1/3 throttle, and it would run but not idle. After a few minutes, it would idle fine. Drove it a little, and it ran fine. Shut it off, cranked up and idled ok. Still no scan codes.
What the heck's going on here?

Jack

 

try cleaning or replacing the IAC motor,it sounds to me like thats acting up now

 

Either the battery was bad (too low of battery) or the alternator is bad. Judging that you don't see a problem now I would be one to asume the battery was really low. Now charged above 12 volts it can now properly power the diode bridge in the alternator and create an electric field that will properly power the PCM. THis is why you had to keep you foot in it for a little time (to keep the output up enough to run the motor). Also understand that it does theis everytime you battery is too low.

In other words the battery was too low....IMHO


Double chech that the battery is good by taking it to the place you bought it from and have them load test it. Most auto parts stores will also do this for free and you don't even need to take it out of the truck. At this time they can also check the output of the alternator.

 

Here's another update. Now I have a new alternator and battery. It's been fine 'till today. After driving about 10 miles and shutting it off for about 10 minutes, it did the exact same thing. When I tried to crank it, it fired and died immediately. Now it cranks, but doesn't fire.
When I turn the key on, the lights on the dash don't always come on right away, and I hear a clicking that sounds like it's coming from the firewall, but I can't locate it.
Any more ideas guys?

Thanks,
Jack

 

Update part two:
When this truck idles for a few minutes, the voltage still drops way down, the Check Guages light comes on, and the voltage comes back up to 14.