Alright, I need help, I give up. I have a '03 Durango, 4.7 STX. For the past couple of months it started to give symptoms which I can not figure out. As I am driving, my radio will cut out and then my lights will brighten, both dash and headlamps. This started occasionally, once every couple weeks at best. It had developed into several times a trip, which finally capped off by blowing both high beams simultaneously. I have replaced the PCM and a Cam Shaft Sensor which was, I presume, blown in the last episode. I have put a DVM on the battery and watched it for over an hour and I have a constant 14.3-14.4 Volts no matter what I turn off or on. Any ideas would be greatly appreciated.

 

Beens you have been watching it and it is happening when load and no load is present. I will suggest pulling that alternator and taking it to be tested as I suspect your voltage regulater is bad. It is biult into that altenator and if it goes bad it either does not charge enough or it can over charge causeing spikes and blowing circuits/fuses bulbs an such, but before this check all your grounds the chassy grounds remove clean up reattach and prime over it instead of applying the ground onto painted chassy as is with most factory grounds try checking the grounds connections and ground wire conditions. Then if all seems well pull the altenator and take to advance or whomever you deal with and have it tested it is better to be tested off the motor to be sure it is not the problem as then you will know it is somthing else. keep us posted.

 

Thank you, I will check that more thoroughly. I have checked most of the grounds and they appear to be in good shape. The only reason why I have not pulled and checked the alternator was due to anything I read states the regulator is part of the PCM, hence why I changed that. I will pull it though and get that checked likewise. Thank you and I will keep you posted.

 

No, it is in the PCM...

Per the 2002 Factory Service Manual:

ELECTRONIC VOLTAGE REGULATOR

The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulating
circuit located within the Powertrain Control
Module (PCM). The EVR is not serviced separately. If
replacement is necessary, the PCM must be replaced.

Operation: The amount of DC current produced
by the generator is controlled by EVR circuitry contained
within the PCM. This circuitry is connected in
series with the generators second rotor field terminal
and its ground. Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. The
EVR circuitry monitors system line voltage and battery
temperature. It then compensates and
regulates generator current output accordingly.

 

Check you Battery Temp Sensor.. when they go bad they can tell the PCM to send out way to much voltage.

You can test it yourself with a digital volt meter. Best to go it early in the AM before the truck has been started for the day. With the sensor having a temp of 75F-80F you should get between 9,000 - 11,000 ohms anything more or less replace the sensor... Hell, there only around $20 i would just replace it anyways...

 

I wonder if that sensor was the cause of a prob I had last summer. I was on a freeway in Abq when 60+ MPH winds and a driving rain popped up for 30 mins, everyone was doing 20 MPH at best. My alternator quit, P-code for it popped up, and I hobbled as far as I could then had to get towed (rain and wind had let up to normal by then).

After a night in the garage drying out, I cleared the code, and it started and ran fine and has been perfect since.

 

I am sorry OP I thought the regulator was biult into the altenator I am used to my gm trucks I am not familiar with the 4.7 or dodge suv's in general I guess. I had a few to many beers yesterday. I answered the qeustion without knowing. I am man enough to admit my mistake. turned 35 today I celebrated to much yesterday.

 

+1 Old School

Oh it's all good akuser47, however some of your post does make sense. The alternator is governed to only produce a maximum of 14.3 - 14.4 volts, so there is a "type" of regulation on it's output. The reason is the battery must charge with the higher output and amps, whereas the truck must run regulated via the PCM. Here is some information you might want to check out:

https://dodgeforum.com/forum/1st-gen...questions.html

and also here: https://dodgeforum.com/forum/1st-gen...ng-relays.html

dn61066<---I've seen these issues like this happen with a bad battery cell touching ground. Maybe time to get a new battery and clean the connections real good. Sometimes even a load test can't rule out a bad battery. Also a battery temp sensor might be your issue, again illustrated by Old School. Also you might have a CTM issue going on but rule out everything else first.

Jeeper<---Water in the alternator will do that, ground it out causing the failure. Once dried works fine.

 

Thank you for all the GREAT information and responses. I also would like to verify all my ground points to make sure they are all good, I have verified some but not sure if I found all of the main ones. Does anyone have a diagram showing location of all ground points to help ensure I didn't miss the one that may be the issue?

 

Well tonight I replaced the Battery Temp sensor, $26, put the battery back in and it would not turn over. Replaced the battery, which also tested bad coincidently. Took it out for a test drive and no apparent overvolts, at least no radio kick out, however I think I noticed a few flickers, bright, on the headlights.... I am crossing my fingers and hoping fr the best ... Will keep you enlightened as time progresses. Thank you again, I really do appreciate the help. Any other insights or thoughts would be greatly appreciated and considered.