I'm hoping someone can help me out with my TC lockup issue, I'm at my wit's end. Truck is a 98.5 24v, only real modifications are a BHAF and Edge EZ. Trans was rebuilt about 100k ago with billet torque converter and full R&R.

I've been chasing a locked torque converter issue for months. After researching the issue I tried a number of different fixes. Flushed and filled the trans, pulled the valve body and inspected, replaced lockup solenoid, checked lockup spring, bypassed the trans cooler, and finally checking for AC noise. Upon checking for noise, I used a cheap DV and came up with 30V AC. Used a Blue Point Pen-Probe style DVM and the AC voltage fluctuated and was well over 0.1VAC. Replaced alternator with O'Reilly reman and same readings. Returned that reman and put in the existing alt.

Removed the 140A fuse for the alternator and issue remains. Seperated the ground from the loom on the back of the alternator and covered with aluminum foil. Issue remains. I tried adding another ground from the battery to the body of the alternator, no change. I then tested the system, with the 140A fuse for the alternator removed, and there is still 2.48V AC at the bridge of the fuse and fluctuating at the battery terminals. What is going on??? How is there AC noise when the alternator fuse is removed?

Couple more details - the TC will lock and unlock. Not on the highway, it's usually fine there. When cold, it behaves normally. After warming up, the TC will lock. It also will unlock randomly and stay unlocked for a little while. If I turn the truck off while it's unlocked, then start again, the TC will usually lock. Is my PCM toast? ECM? Did my alternator fry everything already? The VP44 and lift pump were replaced about 40k ago. I've posted this on a couple other forums in an effort to fix this as it's been ongoing for nearly a year.

 

Did you try the 1k ohm resistor trick in leiu of factory temp sensor?

 

I did that last winter for a while for better MPG while I was driving the truck every day. Not sure how that would help?

 

Ithink it was Geno's but not sure, I bought the kit to splice into the wiring loom. I think it's a resistor but whatever it was it stopped my lock unlock stuttering.

 

Thermistor changes resistance value on temp change. Stock one can go whacky, telling PCM fluid is too hot or too cold for converter lockup, when it is really ok (probably). Lousy connection can have effect on that as well.

 

Okay, that makes sense. I checked it, it was slightly dirty so I cleaned it and put the 2.2k ohm resistor back in place (previously was plugged in like stock).

I removed the Edge EZ and also the trans relay from the fuse box under the hood. We'll see if this helps, although I'm not getting my hopes up as it was still locking afterwards in the driveway.

Thanks for the help so far guys!

 

I thought you were having problems as the converter clutch unlocking when its not supposed to....its locking up randomly? Usually that is the converter going out. Or possibly a grounded wire (chaffing), but I don't think the valve body will hydraulically allow lockup in 1st. Not without modification anyway.

I think you could narrow it down by clipping the B11 (I think, lookup which wire for lockup mystery switch) wire, PCM switched ground to lockup solenoid. If it still locks up you need a converter most likely.

 

Yes, locks up randomly. Well, I think there's a pattern to it. After removing the trans relay, it no longer locks up but I can tell that the converter is trying to. Could this be from not enough fluid flow to the TC?

I can try to clip the b11 but I believe this may be a valve body issue.

 

i have a 12 valve and a 47re that had the same issue. I cleaned the battery posts and cables with the cleaning tool then put dielectric grease in the battery connector ends. I know that these trucks have horrible ground issues... i ran a 10 gauge wire from the passenger fender to the passenger battery, then a wire from the battery to the alternator on the bottomm bolt. Make sure you heat shrink all bare wire at the eye connectors on the wire. dielectric grease the bolt on the alternator as well. my trans has never shifted smoother, going on 2 almost 3 weeks with zero problems. thats what i did, not sure if there is a big difference with the 24 valve. worth a shot before spending a fortune on it! good luck

 

Thank you Rank, I will try that. I'm taking it to a local trans shop that builds many diesel set ups a month. Before sending it over, I'm going to drop the pan again, make sure the spring is broke (again), make sure the filter(s) are not clogged, and inspect the valve body once more.

If all that plus the new grounds don't fix it, I'll probably throw a new converter in there and try that. 140k is a lot and maybe it's the converter after all.

 

Big thanks to RANK12VALVE! Looks like this worked. I will keep everyone posted if it goes back to it's old habits but right now it's working very well.

Ran the two wires like he stated, one from the negative battery terminal on passenger side to ground post on the alternator and another wire from the same battery terminal to the stud on the shock mount. Also pulled the pan on the 47re and checked all the filters and didn't have even a trace of material. Took it down the road while it was cold and everything worked normally. Let it sit and idle in neutral for about 30 minutes while I cleared off my roof and waited for it to warm up. Took it for another short drive, about 15 minutes, and it behaved normally the whole time.

This is a relief, I hope it stays. Much cheaper than a rebuilt or even a converter. Can't believe this was a 15 minute change! Thanks again!

 

Not a problem! Glad that it worked, hopefully this is able to help more people in the future! Cheers!