xp8103

For some reason I don't remember this happening before but maybe I'm just daffy.....

It seems like my trans (47RE) hunts at times if at just the right speed or just the right load. In fact, I've felt it shift only briefly between gears (both in the tone of the engine and the slight lurch that comes with a shift). It also seems to hold a gear longer as it's shifting up thru. I assume that the shift profile keeps the engine in or around it's optimal operating RPM but I don't remember it acting like this.
I had the trans serviced last year, late fall sometime, change the fluid, fliter because I haul a camper on it now and then and had no idea if it had ever been serviced before.

I PASS GAS

Is it actually shifting gears, or the torque converter unlocking and locking? I had this happen, and read that the common cause is a bad ground. There is a very detailed thread on this somewhere about which grounds to add as well as adding a grounding strap. There is also a noise filter for that circuit that you can add.

Mine was doing this when cruising around 35mph (I have 3.73 gears so give or take a few if you have a different ratio.

xp8103

I guess that's a good question. How do you tell the difference between shifting and the TC locking and unlocking?

Geico266

At a constant speed around 45-50mph the TC will just unlock & lockup again without any pressure on the peddle.

Caused by bad grounds which causes "electical noise" to confuse the ECM.

Several threads to help. Good news it's cheap to fix, bad news takes a few hours to do it right.

https://www.dieseltruckresource.com/...highlight=Lock

xp8103

Sounds like grounds are the place to start. Are alternator brushes a problem area? For $25 sounds like replacement can be done without an issue??

Geico266

Yes, sir! Worn brushes can cause "noise" too. Good idea to replace them.

The best place to start is the battery to fender grounds on both batteries. Scrape the paint off and get it to bare metal. Then run a NEW ground from the ECM (behind the aircleaner) to the battery ground on the fender. Clean the ECM ground wire also. Take yout time and even clean the screws. I wire brush on a die grinder speeds things up. Scrape all paint off, and cover with dielectric grease when you are done.

That should do it!

If that gets some of it you are on the right track. If there is still a problem you'll need the noise filter from DTT.

xp8103

Went to the DTT site, didn't see the noise filter. Is there something I should look for??

xp8103

Well, FINALLY had a chance (and nice weather conicided) to get under the hood to reground. Did so on both batteries, cleaned the neg post on the passenger side as it was the only one with "growth" annd then cleaned the ECU ground. No more hunting!
Woo hoo!!

jeepmanjr

Howdy! My first post - thanks for having me!

I've experienced the lock/unlock issue with my '99 several times over the years, nuthin' bad though. That is, until recently. 35-40 mph locked in 3rd and 50-60 in OD. In/out, in/out.... I have a TC lockup switch which I was forced to use to prevent it from happening. I did some research on the Net and this is what I did:

My resources were limited because I was at work. I took an aluminum pop can (yeah...we call it pop where I'm from! ) and cut it into two strips. I wrapped them around the black/tan ground wire running from behind the alternator to the pass side batt and taped 'em in place. On my way home the TC never disengaged once except for normal operation. WOO HOO!!

Perm fix: I wrapped the entire length of wire with a couple layers of aluminum foil. Then I took the same length of RG-8 coaxial cable and removed the copper shielding, slit it down its length and soldered a short piece of #12 wire to the shielding end. I wrapped the shielding around the wire and aluminum taping it in several places. The wire got a solderless connector on the other end and it went to ground. The whole length was then covered with black wire loom/covering. You'd never know it was there.

The ground wire can actually lay across the alternator and apparently is picking up electrical noise. Supposedly, this noise can travel to many different components via the ground wires and cause all kinds of problems. I detail my engine compartment regularly, so who knows, maybe I moved the wire around a few times causing the intermittent problem.

Anyway, before you go scraping paint, etc., give this a try. An extremely easy fix and no filter was needed!

Danderson

I just performed the Dunrite Transmission tinfoil fix as outlined on the homepage of the "other site". Worked perfectly!

xp8103

It's a neat concept but aren't you really merely masking the problem rather than fixing it?

Ranman

So I'm reading this and wonder if it is the cause of my chatter going up a hill on the way home from work. If I put my foot in it while in any other gear than 1st or 2nd it would start to chatter. I thought I had a bad TC and would need to get to replacing it soon. Went out and cleaned the grounds and tin foiled the wire over the Alt. Covered it with a wire loom. Took 30 mins total. DANG!!! .........I love this group. Thanks!

Puke

Reset your APPS before you go too far looking for other things.
It's an easy re-set. Unhook your batteries completely, leave them off for an hour or so (make sure to leave your key on), then re-hook them up (after your've turned your key off), turn on the key, depress the accellerator pedal slowly and then let out slowly. Then you are done,,,,BUT FOR HELL SAKES, FIND THE INSTRUCTIONS ON THIS SITE (WHEREVER THEY ARE) AND FOLLOW THEM, I THINK YOU NEED TO LEAVE YOUR PARKING BRAKE ENGAGED, ETC.,).

projectRam

thanks i did the two strips of beer can and taped with black tape and it is fixed after five years thanks