Was dead battery, now excessive voltage

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

Went to start the liberty this morning, had a dead battery. Left it to charge today at 2 amps. Got home this evening and it fired up fine. But now I get a CEL and it's for excessive voltage. Confirmed that voltage spikes with the engine revving with a meter. I know Chrysler used to regulate voltage through the ECM, is that the case here? Meaning I've got a dead ECM.

flash7210 · **Posted:** Tue Feb 23, 2016 7:42 pm

On the CRD, the voltage regulator is part of the alternator.
I fixed mine myself. See here:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=83913&p=885630#p885630

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

This alternator had been replaced before by me from Advance Auto. So it carries a lifetime warranty. So I went to the local store, there tester was broken. So I went to the next town over, they didn't have the cable to test it! Thankfully the rep at the store knew me from the other location. I had seen 17V or higher when it was running. Plus the DTC stating the same. So they have one ordered for me.

Thinking back, I had a dead battery before this. But I thought it was a light left on or something. I'm wondering if the alternator failed and has an internal short that was draining the battery.

I just hope it's isolated to the alternator and not anything with the ECM.

Billwill · **Posted:** Wed Feb 24, 2016 1:44 am

patracy wrote:

This alternator had been replaced before by me from Advance Auto. So it carries a lifetime warranty. So I went to the local store, there tester was broken. So I went to the next town over, they didn't have the cable to test it! Thankfully the rep at the store knew me from the other location. I had seen 17V or higher when it was running. Plus the DTC stating the same. So they have one ordered for me.

Thinking back, I had a dead battery before this. But I thought it was a light left on or something. I'm wondering if the alternator failed and has an internal short that was draining the battery.

I just hope it's isolated to the alternator and not anything with the ECM.

I hope for your sake that it is the alternator or else you have a wiring problem probably or maybe a bad ECM.

I had six bad wires in an inaccessable harness that were shorting to ground or to some other random wire. If I did some action such as turn on front wipers or the air-con kicked in...voltage would shoot up to 17 volts, "Ping" and engine shut down.

I eventually isolated the bad wires but by this time the battery had boiled itself dry!

WWDiesel · **Posted:** Wed Feb 24, 2016 6:24 pm

Excessive charging voltage can kill a battery in short order! It can damage internal connectors, warp plates, melt plates, and / or boil battery dry of electrolyte.
Be sure and have battery tested after you get alternator replaced and confirm charging voltage AT battery is within acceptable limits.... :wink:

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

Wanted to wait a week before posting, but it appears the alternator was the problem. I think something failed internally and shorted, that's what caused the dead batteries. Thankfully it would seem that the electronics are not fried.

Thank goodness the ECM doesn't handle voltage regulation on the CRD!

Billwill · **Posted:** Sat Mar 05, 2016 3:56 am

patracy wrote:

Thank goodness the ECM doesn't handle voltage regulation on the CRD!

According to Keith at GDE the 2005 CRD does have the ECM control the voltage regulation inside the alternator while the 2006 CRD has internal regulation inside the alternator.

The Service manuals for both models have contadictory informatiom as to how this is done with the Theory of Operations not matching the wiring diagrams :shock:

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

Not sure what to say, that link posted above showed a voltage regulator. And my issue was resolved with replacing the alternator.

Was dead battery, now excessive voltage

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