I am posting this for my friend (neighbor to my mother). He has a 24V Ram, '01 I think. Anyhow, he has been fighting the lock-unlock problem for a while. I had him pull the alternator fuse and try it. Same thing, no change. I also put a multi-meter on the alt to test for AC voltage and it was .013 volts at the highest. I suggested checking the trailer plug and possibly the brake light switch. He did say that if he cleaned the battery terminals and reset the APPS it might be good for two months or two days. What else should he check?

Probably wouldn't hurt to check all the grounds and battery terminals and the batteries as well. I have been fighting a something close to that for a while now.

He has cleaned the battery terminals and that is when it may work for a month or maybe a couple days. What other ground are you meaning?

No other ideas?

There is a ground going from the PCM on the passenger side behind the air filter. Both batteries ground to the block just follow the cables. Tue drivers side battery has one on the frame as well . it is in the wheel well. Also check the connections going to the fuse block under the hood

Thank you, I will pass the word on.

Well I have to throw this out there cause it just happened to me. The overdrive and T/C lock up solenoids are a pair and somehow I managed to fry both in the transmission.

Well I have to throw this out there cause it just happened to me. The overdrive and T/C lock up solenoids are a pair and somehow I managed to fry both in the transmission.

So, how did you diagnose the solenoids?

PCM, ECM and VP44 all get there ground from the battery ground cables. There is no body ground connection for those units.
 

 

I had him pull the alternator fuse and try it.

 

Did you have the field lead pulled too? But its odd there is no AC noise measured. The only reason I asking about the field lead is Pepsi was explaining how his was wore out field brushes causing EMF noise from the arcing of the brushes.

MnTom this issue came up when i was going camping over the 4th weekend. Started up Mt. Hood and ran into an issue of the truck rolling coal really bad then not wanting to up-shift/down shift. When I got it home I pulled all 6 injectors and had them tested found out that 2 of the injector tips were not sealing. Had them fixed did the reinstall and was still having a trans issue this time i didn't have 7600lb behind me when i hooked it up to my buddies Modis and scanned it I found 2 trans codes P0743 Torque converter clutch solenoid /trans relay circuits and P1765 trans 12-volt supply relay controller circuit. So these 2 codes are what sent me to the trans. 

 

codes can be found here

 

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes

I don't know about any codes on his truck, so that may point to something. When he would take a test drive and go by me it would be constantly going from lock to unlock at about one second intervals.

I was having the same issues. Had the Trans rebuilt w all new solenoids, RV TC. Was fine for about a year, started all over again pulling a light camping trailer from a vacation 600 miles from home. I spent about 6 weeks trying to figure it out, no luck. Took it to a new diesel performance place in town, he just took a 6 speed manual out of a 2001, my lucky day, I didn't look back. No more issues, the truck seemed like it gained 60HP w the 6 speed. I love it, Dave

I am posting this for my friend (neighbor to my mother). He has a 24V Ram, '01 I think. Anyhow, he has been fighting the lock-unlock problem for a while. I had him pull the alternator fuse and try it. Same thing, no change. I also put a multi-meter on the alt to test for AC voltage and it was .013 volts at the highest. I suggested checking the trailer plug and possibly the brake light switch. He did say that if he cleaned the battery terminals and reset the APPS it might be good for two months or two days. What else should he check?

  

Replace APPS?

Replace APPS?

That may be what it needs too.

There was another post some where... I just read it. But you might consider replacing the speed sensor. (Another unusual solution)

I also had the same issue. If I cleaned my battery terminals on the passenger side battery it seemed like mine would be fine for a few days or a month. There was no pattern to when it would start acting up. I used spray grease and covered the terminals on the passenger battery and that gave it about 6 months before it acted up again. I was coming home from work one night and the truck died going down the highway, fuel pump wouldn't run. Don't remember what codes were in it but turns out my ecm decided it was time to die. Bought a used ecm from a friend of mine and haven't had the unlock issue once and it has been close to a year now.

Might be a day or two before I find out what he is doing. I was talking to him yesterday and he said something about today going to be a long day. He is a mechanic for a cement company and said that he was going into a mixer today because of a 600 yard pour scheduled. That is one huge pour......

Mine ended up being the negative/ground cable from the back of the alternator rubbing against the battery tray hold down (wire on metal contact). I just wrapped the wire with some fuel line and zip ties and haven't had a problem since.

The guys at O'Rieley's thought mine could have been an APPS as well. The deal they were going to give me before I did the 6 speed swap was if that wasn't my problem bring it back for a full refund if that didn't work. Think the cost was like 138 bucks if I remember correctly.

The best fix for me during all my troubles was the TC lockup switch, just cost me 5 bucks for a toggle switch & I had the wire.

Dave

The best fix for me during all my troubles was the TC lockup switch, just cost me 5 bucks for a toggle switch & I had the wire.

Dave

The problem I have with that is you are not fixing the problem, just covering it up. If the truck ran for over 10 years without it there is some reason for it to act up. It just takes time and effort to find it then fix it.

I have started having lock up and OD issues too. More cycling between 3rd and lockup and it can't decide at certain speeds/RPM's OD will cycle in and out quickly. Like right in and out.

Can I use a non digital VOM to detect the small AC noise from the alternator? I'll start cleaning electrical connections.

Anyone using battery connection spray on the connections? You know, the red stuff that dries and seals connections.

Would the main negative cable on the right side rubbing on the metal elbow between turbo and intercool potentially be a problem?