DodgeDawg2500

Hello,

I have done some searching and read the Tech articles on this issue and plan to clean all grounds connections etc.

I am wondering if I should: clean all grounds/connections as outlined in tech article, then reset APPS, and if neither helps/works then buy a noise filter or tape the alternator wire. (Which wire is it anyway? The tan and black wire?)

What is the latest opinion on this issue? This just started for me where I am cruising along around 35-50 MPH and the RPMs go up and down erratically, the truck feels like it's "surging" and then it stops. If I let off the gas or increase speed it goes away. This is the "hunting issue" right?

Thanks in advance for the advice.

Vman4220

I battled this with my 2001 and was told I needed a new transmission until I was lucky enough to find the invaluable information here. By following all of the directions that you have mentioned and purchasing the noise filter from Geno's ( recommended on this forum ) the problem was resolved. Instructions come with the filter to tell you which wire.

snowjoker

What I did when nothing would work was run a gound wire directly to one of the tranny pan bolts.. it ended my problems

samaf

I found a broken wire in the wiring harness going to the trans and mine was doing the same as yours. Good Luck


Sam

Redlinear

I called that "bucking". Truck would be in overdrive and start bucking at anything resembling an almost uphill grade.
You'de have to let off, or give it fuel to make it stop.

Danderson

The noise filter cured mine on the '98.5. Five minute fix.

DodgeDawg2500

Thank you for all the replies. I am going to work on this over the weekend.

Where is the PCM? Can anyone post a picture of it? I have an AFE Stage II intake and I am thinking the housing may cause issues when looking for ground wires etc from the PCM.

Where do the wires hook into the transmission? Is this something I will see easily?

jrs_dodge_diesel

PCM is on the passenger side of the firewall.

The cheapest fix for this problem (it's free), is to clean all of the grounding points (there's six key points). Clean all of your grounding points.

Clean both negative battery terminals. There's also two wires going from the negative terminals to the chassis. Clean the terminal end on the wire and the chassis point. The crucial one is the PCM ground. The PCM is on the firewall, passenger side. Clean both end of the ground wire and the connection points. I replaced my PCM ground wire due to the amount of corrosion I saw.

That should take care of it. In most cases the hunting is caused by a "ground loop". Those are caused by dirty and corroded ground connections, which puts noise and stray signals in your electrical system. And since overdrive is electrically controlled, it gets affected. A bad battery, wiring issue, or electronic component failure can cause this problem as well. The power filter IMO, is a band-aid that doesn't address the underlying cause (the grounding issue).

DodgeDawg2500

Thanks for all the replies.

Last question: I am pretty sure the negative battery cable grounds are easy to find, but are the ground wires from the PCM easy to find?

Thanks.

jrs_dodge_diesel

Yes, one of the PCM mounting bolts has a dedicated grounding wire running from that bolt, to the chassis. The wire is about a foot long.

My PCM grounding wire was the worst looking one on my truck with a decent amount of corrosion on the wire crimps. I replaced mine with a new wire, and crimped and soldered on new ring terminals. I think this wire is a critical one, since it is the PCM that controls the O/D clutch.

Tallguy67

ok, if I have a few mins over the weekend I am going to try and create a document about this and put it in the wiki so I can find it easily. One of us pops up with this problem every couple of weeks. I am not ranting, just trying to be helpful. I started dealing with this same problem just about a year ago. I finally solved it for good in August. In 3rd and 4th gear and when on the throttle gently the truck would buck the rpms up and down about 500rpm between 50 km/h and 90 km/h. Stay hard on the throttle from sit still until 90 km/h and no problem. I started out by resetting the apps. Problem went away for a couple of driving hours. Replaced apps, problem went away for a few more driving hours. I cleaned ALL the grounds that came off both negative battery cables and the problem went away for about 20 driving hours. I cleaned all the grounds and added dielectric grease and the problems came back after about 30 driving hours. By this time I was getting REALLY good at cleaning the ground wires. Someone on the forum sent me a link to a permanent fix for the problem but it involved cutting some wires between the APPS and the PCM and running new ground wires to the tranny. I was prepared to go that route if I had to but I decided to try one last thing first. I bought the transmission noise isolator from Geno's for about $10 I think. When it arrived, I cleaned the grounds one last time, installed the noise isolator (took less than 5 mins) and I have never had a problem since. If you do each of these things and still have the problem, check back in and let me know, I will find the diagram for the PCM/APPS/tranny rewiring job and post it up here.

DodgeDawg2500

I worked on the truck this weekend. I did not see a speck of corrosion on any of the ground wires. However I did see some on the negative battery connections, so I cleaned them and sprayed some anti-corrosion gunk on them.

I also removed the drivers side ground from the body, just to make sure there was nothing between the connector and the body that could be causing the issue, still no corrosion. Then I put the sheet metal screw back in and began to tighten. Yes it was straight. The screw would not go back to factory tight, so I ended up with a machine screw, a few washers including a lock washer and a nut, problem solved. I wanted to post this for a couple reasons - 1. It seems like it should be stated, 2. I definitely did not want to mess with anymore sheet-metal screws as there is no way I could get a nut on the back of the connection for the PCM.

I also: -reset the APPS,
-noticed the wire from the alternator to passenger side battery was taped up, so I removed the old tape and retaped,
- zip tied the cable from the alternator to the mounting point on the battery housing
-finally checked the wiring harness on the transmission.

The "hunt" or bucking issue I originally posted was very sporadic in nature, so I have no idea if this worked. I am heading to GA for the weekend and will report back if anything arises.

Thanks again for all the replies. This is a great site with a wealth of information.