Tallguy67

Hey Alberta folks,
I am going slightly nuts. My TC keeps unlocking and the locking back up. This started back in the spring. I replaced the APPS with no improvement. Then I cleaned all 5 grounds off the batteries and PCM. The problem went away for about 20 hrs of driving. 2 weeks ago I cleaned them all again (including battery posts) and gave everything a light coat of dielectric grease. That cured it for about 90 minutes of driving time and the problem is back again. I am willing to try the noise isolator that folks talk about that supposedly solves the problem. I know I can mail order it from Geno's but I am hoping for a faster solution. Do you know if I can buy them anywhere local to Calgary?

Heimie

I tried the noise isolator too. It didn't help me. What I did to cure the problem was what you did. Clean all the grounds and add grease. That helped a little. I added a separate ground from the TCM (I think, it's the one on the firewall on the passenger side) to the battery. The biggest, most noticeable difference came from when I cleaned and added the grease to the A/C compressor plug. This one was really dirty because of all the oil from the filter when doing oil changes. Huge pain to get to, but seemed to do the trick. Also don't forget to do the same with the altenator connections. It seemed to last a whole year (about 35000 kms for me) before I had to do it again. I did it again, and now it has been almost two years. Good luck! Hope this helps!

Tallguy67

Thanks for the additional ideas Heimie. I will give those a try as well.

Marine

I just cleaned all the terminals and added post shims today. Also cleaned battery grounds that go to the inside fenders. Also cleaned the ground at PCM and firewall. Haven't driven it yet but will find out tomorrow how it went. My alternator is throwing out 30 volts AC as well as 14 volts DC. I'll have to look into that some more.
If what I did today doesn't fix the issue I'll look at the A/C plug.

Marine

Been driving around today and so far no unwanted unlocking/locking. :-)


From my torqued out reuterbender

torquefan

I've messed around with a lot of those trucks with that condition, and the repair I've ended up with, that works every time, was a fix that was once spelled out on the DTT website. It involves running a signal wire directly from the APPS to the PCM and eliminating the signal wire that was routed through the ECM. The one improvement I made to their procedure was to use a shielded wire for added protection. Pretty easy and effective fix and the price is right. Hopefully it's still on their site somewhere. I'll have to take a look for it.

Tallguy67

Torquefan,
If you can find that it would be MOST appreciated. While cleaning grounds IS an exciting way to spend 45 minutes, it is starting to get a little stale
Trust me, I am doing a good job of it too, I am polishing everything up to nice shiny metal with a sanding drum on my dremel and then I gave everything a light coating of dielectric grease. Like I said, this latest cleaning cleared things up for about an hour of driving time. That isn't a good return on investment for a 45 minute job.
I could even understand if the truck was parked outside in the rain or if this was winter when road salt and snow melt could be accelerating corrosion. This truck gets parked in the garage out of the sun and all of the elements. I wish I got pampered as much as it does.
I appreciate any help.

Marine

Did you install battery post shims?

Tallguy67

What are battery post shims?

Marine

http://www.princessauto.com/pal/product/8064453/

torquefan

Hey, I found a copy of the same thing but from ATS. It is just the same as what I have done in the past. Let me know if you have any questions.
http://www.atsdiesel.com/additionali...02)%20v1.0.pdf

Tallguy67

Torquefan - One quick comment and question. I notice this is titled '4th gear hunt', I am having the problem in 3rd and 4th gears. Is it all related to the same root cause and solution?

Marine

Yes.

Sent from my torqued out reuterbender

torquefan

Yes x 2. I searched some threads here and other websites, trying to find the site with that info on it. Saw claims that some people had luck with the noise filter, some did not. Same with this rewire procedure. The trucks that I looked at for this problem seemed to have some things in common: looking at the APPS signal with a graphing meter showed a clean signal between the APPS and ECM, but a spiky rough signal from the ECM to the PCM. I tried driving them with the alternator field disabled, with no change, so I felt that ruled out the alternator as a cause. I had started out by cleaning grounds and battery connections, with no change in the condition, and also tried a "known good" APPS, also with no change. After the rewire, the problem disappeared and never came back that I was aware of. I suspected an internal ECM problem, maybe a capacitor starting to get flaky, but other than cleaning the ECM connector and verifying good pin fit, I never tried swapping or replacing ECMs to see if it made a difference.

Anyway to answer your question, some trucks would act up in 3rd gear as well as 4th. Good luck with the fix.