Engine/Transmission (1998.5 - 2002) Torque Lock/ Unlock and poor shifting

[turretplug]

My torque converter was constantly going thru the lock and unlock cycle while driving at speeds between 40 and 50 MPH. I had the APPS Noise Isolator installed based on reading many of the posts in this forum. The problem is two fold now. The transmission does not like to drop into overdrive unless I am on a perfectly flat road or a down hill and the cruise control is no longer functioning. Overall the transmission shift points based on load and speed seem way off from what they used to be. Looks like my one fix has left me with another problem and I do not want to just start throwing parts at the system without a plan.

 

[JLandry]

If your transmission is having difficulty going into overdrive (4th gear), then there may be a problem with the 3rd to 4th gear shift solenoid.

If you have a lot of miles on the transmission, without resorting to doing a bunch of tests to determine the exact problem, it can't hurt to replace the 3rd to 4th lockup solenoid, the governor pressure sensor, the governor pressure solenoid, and the output shaft speed sensor. All of these parts wear out in time and can be ordered online for very reasonable prices at Transmission Parts USA. You can easily replace them yourself.

Best regards,

John L.

 

[cerberusiam]

Gov pressure sensor, gov solenoid, and output speed sensor to start with, they are the source of just about all the shifting problems aside from a hard part failure. If you have not replaced them in 40k they are due.



Try pulling the APPS filter off and see if that makes a difference. If it does great, you will know your on the right track. If not throw it away as it is useless for a permanent fix anyway.



If the solenoid is holding lockup fine the rest of the time and you have no obvious slipping issues don't waste the money on the solenoids and harness. You need to remove the source of the noise that cause the lockup fluctuation and the only way to do that is get the alternator ground wire and charge wire OUT of the main harness and reroute them.



That will cure 95% of the lockup fluctuation problems. The rest is just because its a flaky system and its getting old. Putting in a triple disk TC and shift kit will a lot of times solve the problem also.

 

[turretplug]

I don't have any slippage issues with the transmission. With the APPS filter removed the TC goes back into its lock and unlock cycling. The reroute of the alternator ground and charge wire. What am I trying to reroute them away from? Do I need to use a shielded wire like something that would be used for a strobe? Truck has 153K with regular 30k transmission service. I recently changed to synthetic ATF and put in a MAG-HYTEC double deep pan. The TC lock and unlock problems were present before I changed the fluid and the pan.

 

[cerberusiam]

Does it shift correctly without the APPS filter, but, the TC plays its game at a steady speed?



Does the TC only lock\unlock at steady throttle in the 35-50 mph range, or, does it do it at any steady speed like 65-70?



Look at the harness where the wires are bundled. Both the battery ground wire and the alternator charge wire run in the same harness as all the wires that to and from the ECM\PCM. With the possible fluctuations from the alternator charging in the charge wire, the battery ground wire running right thru or close to the alternator fields there is the potential for a lot of dirty signals thru the main harness.



If you remove those 2 wires and reroute them seperately, one over the rad support and one on the firewall, it takes 90% of the noise potential away from the harness that runs the trans controls. Its worked better than anything else on at least 3 problematic trucks I know of.



Shielded wire on both circuits would be the optimal solution. Ground circuit is maybe not as critical but stray induced noise in the ground circuit will raise havoc at times also.



If that doesn't completely cure it a triple disk TC usually does. The triples take a lot longer to lock\unlock so the slight variations in signals to the lockup solenoid aren't as noticeable. The PCM may still have a fluctuation in the ground circuit for lockup but its so short the TC never unlocks.

 

[turretplug]

The truck does shift properly without the APPS filter, the TC lock/ unlock cycle is confined to approximately 35 to 50 mph, when I am at highway to freeway speeds it locks and holds fine.
I will remove the APPS filter and run shielded battery charge and alternator ground wires. I will use the triple disk TC as a fall back position if the rewiring does not work.
I think I remember an article from the magazine that talked thru a good reroute wiring diagram. Do you happen to remember which issue if there was one. Rather not reinvent the wheel if someone has already come up with a good plan.

 

[cerberusiam]

I do not remember an article on it. Sure there has to be some as this had been discussed before. We just picked the obvious straight forward way to reroute and it worked.

 

[John - K5AWO]

Don't overlook the sensor on the left side of the transmission.

Pull it out, wipe the grunge off of it, and put it back in.
Simple little job, can work wonders.

 

[cerberusiam]

When you pull the passenger side battery ground cable out of the harness you should find the ground wire splits into 4 different pins on the ECM harness. We ran the ground cable back along the firewall and into the harness where it splits for ease. My son got ambitious tracing wires and actually removed the charge wire from the harness but you could just disconnect both ends and make sure they are out of any possible contact with the alternator and run the new one over the rad support and to its mounting point.



Moving those 2 wires completely cured the lock\unlock problems. The only intermittent glitch is in very rare circumstances at low throttle, on a grade, certain engine load, acceleration, and in OD we get a pulsed unlock\lock that seems to be the PCM just not able to decide what it wants. A little more throttle or lockout OD and no issues. A triple disk and mild shift kit should address that.



The crappy OE converters are their own worst enemies at times. The PO had the trans rebuilt because of this issue and it just got worse with time. We tried a filter, tin foil, move the wires, reset the APPS and it had limited effect. The ONLY way to cure the noise problem is remove the source and it works quite well.

 

[JLandry]

For shielding some of the wires previously mentioned, something like Braided Wire Loom grounded to the chassis on one end might work nicely.



Just a thought.



John L.

 

[turretplug]

Thanks for all the input. I will get working on this fix this weekend.
Jon

 

[59Turbo]

Try running a new ground to the pcm grounds, not directly to the pcm case but the actual ground wired in the connectors, that fixed mine after trying all of the above.

 

[SnoKing]

Gov pressure sensor, gov solenoid, and output speed sensor to start with, they are the source of just about all the shifting problems aside from a hard part failure. If you have not replaced them in 40k they are due.



Try pulling the APPS filter off and see if that makes a difference. If it does great, you will know your on the right track. If not throw it away as it is useless for a permanent fix anyway.



If the solenoid is holding lockup fine the rest of the time and you have no obvious slipping issues don't waste the money on the solenoids and harness. You need to remove the source of the noise that cause the lockup fluctuation and the only way to do that is get the alternator ground wire and charge wire OUT of the main harness and reroute them.



That will cure 95% of the lockup fluctuation problems. The rest is just because its a flaky system and its getting old. Putting in a triple disk TC and shift kit will a lot of times solve the problem also.

OK, I am working on rerouting my wires. I have the brown/Orange ground wire pulled out to the point that it splits into four smaller wires near the data plate on the drivers side. Do I reroute and just extend this wire to reach back around via the firewall? Also, I pull the charge lead out and route it across the top of the rad?

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Chris

 

[fox]

I'd suggest checking to make sure the apps filter is connected to the correct wires.
I've not yet seen the issues you have with a noise filter installed correctly.
I did see issues with it connected to the wrong wire once!

 

[SnoKing]

Well it took me most of the morning to complete the rewiring. I made up an extension about 12-14" long for the charge lead to reach the distribution panel. I bolted the extension to the existing lead, tape and then installed shrink tubing over it. For the ground lead I cut it near the plug near the passengers battery and bought 5' of number 8 marine wire and spliced in all but about 7-8" of the 5' piece and again installed shrink tubing over the butt connectors. This ground wire goes under the air filter box and across the firewall and is in a plastic loom.

Will not know if I fixed my problem until I tow again, as that is the only time I had it unlock. It happens around 60MPH will pulling. I see the DTT flash the unlock LED and the TC unlocks if I let up a hair it locks again.

I do have the DTT filter that they installed back in 2004. This problems has always been there. Hopefully it is gone in the garage box with all the nasty tape off the factory looms. That was the hardest and most time consuming part, taking the exist loom and wire bundle apart. Chris

Here is a picture of the alternator lead going up to the top of the radiator.
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And then coming down of the drivers side and the orange extension connecting to the distribution center. You can see the bolted together connection also.
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Here is the ground lead hooking back up to the OEM plug below the passenger battery.
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In this picture is the wiring junction near the VP44. The top wire loom heading back toward the firewall is the ground lead.
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The wiring loom coming up next to the dipstick is the ground lead and going across to passengers side of firewall.
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[JR]

Did this just start with the new TC you were talking about in your other thread?

 

[SnoKing]

Did this just start with the new TC you were talking about in your other thread?

I posted earlier!

"
I do have the DTT filter that they installed back in 2004. This problems has always been there. Hopefully it is gone in the garage box with all the nasty tape off the factory looms. That was the hardest and most time consuming part, taking the exist loom and wire bundle apart. Chris"