Hi
Over the last month ive noticed a change in character from my transmission.
When cruising at about 45mph it has started to start shifting backwards and forwards through the gears going from 1250 rpm to 1500 rpm, if i give it a little more juice it goes away?

Has anyone experienced this before, is it a common problem?

The truck has only done 150,000miles

1998.5 3500 4x4 dodge cummings

Cheers in advance
Grant

 

Try keeping your truck out of OD until 50 mph.

 

Clean all grounds. Both ends of negative battery connnections and the ground wire from the ECM to the firewall. Also check the wires that run on the passenger side over the alternator and make sure they are not rubbing the alternator case.

I just did this on my truck and eliminated the exact problem you are talking about.

 

Cheers mate
Ill go through those and let you know the results.

 

My truck did the exact same thing and had to replace the battery and clean the cables.

 

Mine started doing this at about 100K I cleaned everything, and reset the APPS, and calobrated the pinion factor. It went away for awhile then came back. I am now at 114K and truck is in the shop for a tranny rebuild. 150K on a know 125K tranny is a pretty good run; it may just be it's time.

 

This is how to go about fixing the problem. The problem is that the ECM is picking up "noise" due to a weak ground. This causes the torque convterter to lock and unlock. That's where the fluctuation of rpms comes in at.

 

I went in to a dealership a few weeks ago to get a crank postionng sensor. While there I asked to speak with a diesel tech and they walked me back to the shop and intoduced me to their guy. Before I could get the entire question out he stopped me and told me to do the following. Find the ground connector for the PCM. It can be found right behind the passanger side battery. He told me to cut it out and solder the wires together. Don't use a butt connector, solder it. I could not bring myself to cut the connector out so I cleaned it with electrical parts cleaner and put it back together. The tranny has worked perfectly since. Try it and let us know.

 

I agree! I have trced this problem down to the two gray ground connectors passenger side by battery. Cut the connector out and reconnect & you'll be good to go.

How's everything over on the other side of the big pond? Used to be Ireland was a hot spot for trouble. How did you guys solve that? We could use some advice! LOL

 

I forgot about those. I also disconnected them, cleaned them, and reconnected them using dielectric grease. In the future, I would not be worried about removing them and soldering the connection though.

 

Cheers everyone for your help on this one.
I cleaned up the batterie earths and the grey connector for the ECM (looked **** clean to begin with?) and the problem has gone away
Cheers for helping me save time and money, priceless!
Grant

 

wow. this forum is great. my truck started to do this a few months after i bought it. i will try to clean and check the grounds tomorrow. thanks guys.

 

Had the same problem. What it is rfi radio frequencies interfearances. Sorry about spelling. I talked to dave at gorend tranny. What he said to do is go to your plug on your tps. It is 6 wires. Take the black with yellow tracer and tap into. Not break it just tap into it and run a wire to your ground. It grounds the tps better. I did that and worked great. He is the man. I love their stuff. It's the best.

 

what's PCM ground behind passenger battery?? I see a ground wire from right pcm bolt to the upper firewall(just under the cowl to hood weatherstrip)
is it this?? I cannot see any ground behind battery....