Need help figuring out issue with our 2000 5.9l r/t

Scoggin1092 · Oct 26, 2017

Bought our Durango two years ago...shortly after the PCM went bad....replaced it and everything was fine till June when that PCM went bad....Replaced and again all was fine...for about 3 weeks...driving down the highway and there was a brief (2 minutes tops) overcharge....pulled over and by the time I stopped the volt gauge was back to reading normal...drove it home and all was fine for a few days.....drove it to my shop....and when I got there the overdrive light flashed and the check engine light came on...I turned it off and it wouldn't start...so I figured that overcharge the few days before fried the PCM....so another PCM installed....again all was fine until I romped on it getting on the highway and check engine light came on and it went into limp mode.....carefully drove it home...and have been trying to figure out the issue ever since...I'm listing everything I have replaced up to today....I have had it to 3 different shops and no one can give me a clue as to what the issue or issues are...
My check engine light is still on...and before I took it to the shop this last time I had 2 codes that didn't clear for the mechanic...PO1765...Trans 12 Volt Supply Relay and the Transmission Shift 3-4 shift solenoid....Shop tested the wiring and all came back ok....I went to pick it up yesterday and a new symptom popped up....will not idle...had to feather the gas to get it home...

Replaced battery
Alternator is almost new...have had it benched tested 3 times...came back ok
I replaced all 3 PCM connectors
Replaced CAM position sensor
Replaced the Crank Position Sensor
Replaced Throttle Position Sensor
Replaced Shift Position Sensor
Replaced Shift Position Sensor transducer
Replaced Torque Convertor Clutch Solenoid and the Overdrive Solenoid....
The last shop I just picked it up from said either our PCM was fried since I put it in before replacing what I listed above or it's the transmission (46re)....I am doubting the transmission path since I have never had an issue with it..ie shifting wrong...not shifting...hard shifting....I can disconnect the main electrical connection to the tranny and and shift manually just fine...
I know the bands need to be adjusted but not real sure adjusting them will solve the issue(s) that are preventing me from driving it...
I am at a total loss as to what to try next other than throw another PCM in it and see what happens...I'm hoping someone somewhere can help me figure this out.....

Volphin · Oct 26, 2017

1) What was the root cause of the overcharge condition, and tell me about the alternator you installed.
2) You may have a wiring harness issue. Not real fun to diagnose, but something in the loom is causing the issue in my opinion. You can either A) buy a new engine control harness or B) go digging for the issue. I would start with B, specifically the alternator and charging circuit. You are looking for chafed wires and open insulation visually and then test each circuit with a VOM while you flex the harness. The transmission codes are not likely to have contributed to the issue, but inspect that portion of the harness as well.

Scoggin1092 · Oct 26, 2017

Not sure we ever figured out the root cause of the overcharge.....alternator is not a stock one...I put in a beefier one....and that was put in when the PCM went out the very first time....Dec of 2015....
I did forget to mention that when we replaced the PCM (lost count on which one) it cleared those 2 codes I mentioned....and it was out of limp mode...drove it to my shop and after shutting it off...it wouldn't start...I did have the old PCM which would allow me to start and drive the car albeit in limp mode...I also forgot to mention that after that initial overcharge...the connector to the PCM....one closest to front of car....left if you are looking at it from driver's side of car...had some blackness around some of the connectors that wasn't there previously(hence why I replaced that connector)....after it wouldn't start after the incident I mentioned above....the same connector had the same blackness on it...not all...just around some of the pins.....also it isn't charging right still....think it should read 14 and it reads around 8 .....does this change your thinking or ????.......

MWeed · Oct 26, 2017

If the computer isn't seeing proper voltage all sorts of gremlins will appear. Find the root cause of your low voltage and get that fixed first. Batteries are critical on first gen D's.

Scoggin1092 · Oct 26, 2017

So my next question is.....even though the alternator bench tested fine 3x....could it be bad or should we concentrate on the wiring harness.....and in general what if anything would cause the low voltage besides bad wiring....I have worked on cars for 40 years but this electronic stuff is giving me fits.....

Volphin · Oct 26, 2017

Harness. There is no other viable explanation. Follow the burned pin back. Bet it leads to the charging circuit.
I'd also double check that alternator by disassembling it and inspecting the components. Not all new alts are compatible with your system. Pull one from a junkyard D and run it if unsure. There is no need for more amps than stock...

Volphin · Oct 26, 2017

Scoggin1092 said:
So my next question is.....even though the alternator bench tested fine 3x....could it be bad or should we concentrate on the wiring harness.....and in general what if anything would cause the low voltage besides bad wiring....I have worked on cars for 40 years but this electronic stuff is giving me fits.....

The burned mark indicates over voltage. It may be low now due to some of the current finding another path to ground... a short. I don't care if the alt tested fine. This is obviously an intermittent condition, and an over voltage CAN damage them. When they test them, all they do is measure the output at full discharge. It's important to know what the output is at trickle as well.

Volphin · Oct 26, 2017

Oh, and another item to look at is the battery cables and ground situation. Make sure ALL ground locations are clean and tight. there is one in the front fender well that is known for getting nasty. make sure your battery cables are free from corrosion (even inside the insulation!) and battery posts are tight and clean.

Scoggin1092 · Oct 26, 2017

did clean and replaced all the grounds sometime in July thinking that was part of issue...will double check them againincluding the battery cables.....I am thinking of just getting a stock alternator just to eliminate that as a problem source as well....and after your response I started thinking more and the thought came to me...it might be an intermittent problem.....
Thank you for all of your input.....no one could seem to help diagnose this except to say the transmission might be getting ready to go out...I know the previous owners had a tranny put in.....a year or two before we bought it....now I know that doesn't always mean crap but the transmission was giving us no symptoms of failure...the only thing I noticed was.....it seems to shift into overdrive sooner than I what I thought it should but I don't know the speed it is programmed to shift into overdrive...I believe ours shifts into overdrive around 45/50.....
Again thanks for the input at least now I have an idea of where to go from here....which is more than I have known for almost 3 months....

VviperR · Oct 27, 2017

I would first dump the aftermarket "beefy" alternator. Get a stock oem one. Next you probably shorted fried whatever wires in the charging system. Ds are sensitive to over voltage, thus the new pcms, suprised honestly you didnt blow more up.

Scoggin1092 · Oct 28, 2017

I forgot to ask....will this issue also cause it to go into limp mode.....I did go out and get stock alternator....now I just have to find the bad wire....so while I'm working on it I just want to make sure the limp mode issue is part and parcel of the wire(s) being bad

Scoggin1092 · Nov 14, 2017

Replaced "beefier" alt with a stock one....also replaced the sensor under the battery ....can't find any bad wires...so my next move is to replace the PCM.....my question is..I have found one that is local that says the BCM needs to be programmed not the PCM...I have called around and haven't found anyone who will do this...so do I just keep looking for one that you program the PCM not the BCM...also I found one that is for an 01 5.9l v-8 4wd ....will that one work for my 00?

Need help figuring out issue with our 2000 5.9l r/t

Scoggin1092

Volphin

Scoggin1092

MWeed

Scoggin1092

Volphin

Volphin

Volphin

Scoggin1092

VviperR

Scoggin1092

Scoggin1092

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