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Discussion Starter · #1 ·
Well folks, after completing the rebuild on my 2000 Rodeo, I thought all was well. But, then I noticed the TCC lock up was acting weird. From a dead stop (or a really slow speed) once shifting through all of the gears was complete and the first command for lockup was given, it was not normal. It will lock for a moment, unlock for a moment, then lock down solid and stay locked up good. Now, the more confusing part is the lock and unlock at cruising speed is normal. If I mash down the accelerator hard enough to speed up a lot, it will unlock, speed goes up, then it will lock back down solid when I back off the accelerator with no hesitation or crazy B.S. I let this go on, hoping it would go away after a while, but it didn't. After putting about 550 miles on it, I developed a slight leak at the front pump seal. o_O So, now I've pulled the transmission back out to determine the issue. So far, I've found that the end play on the turbine shaft was out of spec a little. The book calls for .004 - .031, and mine was .042ish. So, not really bad. And I can easily fix that.
Then there was the front pump bushing and the converter hub. They were not getting along at all. The brand new pump bushing was all scored up all the way around, and the converter hub was scored on one side. So, I can only assume the hub was not truly straight. I created a crude set up to try and check the run out on the hub. Here is the video:

So my supplier is getting me a new converter since they promised only .006 of run out. I'll have to install another new bushing of course. I'm also going to try another TCC solenoid just in case. Other than that, I don't know what do here.
 

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Discussion Starter · #2 · (Edited)
Well, after replacing the torque converter, and locating a black front pump seal, I no longer have a leak. I was told to find a black one. “They are better than the brown ones.” This is true y’all. It has a much better lip on it. I also replaced the pump bushing with one from Sonnax. But, I still have a weird lock up issue. I did manage to find a new GM TCC solenoid, so I feel good that that is not the issue. I do have a new piece of information though. When cruising, if I get down to 3rd and then back up to 4th, I get the same bad lockup. I still have good lock up on and off as long as it is still in 4th gear. Works perfectly. I’m at a loss here. I do think it may have something to do with the shift solenoid(s) now that I know it will act poorly just from going down to 3rd. I thought it was only from a dead stop.
 

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The Torque Converter Clutch (TCC) is hydraulically controlled the TCC Control Valve, which in turn is hydraulically controlled by the TCC solenoid, which in turn is electrically controlled by the Powertrain Control Module (PCM). The TCC solenoid control signal is 12 Volts DC On or Off.

Recommend you splice in a 5mm 12 volt LED in parallel with TCC solenoid coil so you can monitor the status of the control signal. When the LED is illuminated the TCC should be applied ("locked").
 

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Discussion Starter · #4 ·
Well, no luck still on my lock up issues. I put all of my original solenoids back in, except the new GM TCC solenoid. I left that one. New filter for good measure. Topped off with 5 quarts of new fluid. I thought at first it was fixed. The very first time it called for lock up as I drove down our road, it seemed to lock up fine. Then I drove some more, and did several gentle accelerations from stop up to 50-60. Each time it got slightly more noticeable until it was consistent again. Lock, unlock, lock good. I have no ideas left. I'll add a test light next Buster, but I don't have great expectations on this. I believe the 12v signal is good. If I tap the brake pedal with my left foot while cruising, it will unlock right away. That's one test I was instructed to do to make sure the circuitry is intact. There seems to be a hydraulic issue here. I just have no idea what??? I'm starting to hate this transmission.
 

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There could be a problem involving the Throttle Position Sensor (TPS) that causes the PCM to switch the TCC solenoid control On and Off. The LED will determine if the PCM is the source of the erratic TCC engagement.
 

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Discussion Starter · #6 ·
Thank you very much Buster for encouraging me to do more testing!

I have new information from last night's testing. I had my wife drive the truck while I sat in the passenger seat with my logic probe and test leads I attached at the front case connector for the TCC circuit. This was very enlightening! As she drove, it would go into 4th and lock up just fine. WHAT!? This truck is actually her daily driver. I said, "This thing hates me! It must only want you to drive it." So, I asked her to keep going. We did numerous stop and go cycles up to 60 mph or so. Then I asked her to give it a little more throttle pressure, and BAM! I was amazed at what was actually happening. It was going into lockup in 3rd, but I thought it was a shift into 4th when I was driving it. It stays in the 3rd lock up for a good period of acceleration time. Then, it shifted to 4th while unlocking at the same time, and locked back down. This short shift into 4th and quickly locking down of the TCC is very confusing. I Don't know, but it's almost like it has 6 shifts. We repeated this process numerous times, and were able to produce the same results over and over.

Now, I had her give it a hard launch, and wow! 1,2,3,lock up, then unlocked into 4th, and just keep going faster and faster. It would not lock up in 4th until she backed off the throttle.
 

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IMHO the TCC is working as expected, but be aware the 00-02 Trooper/02 Axiom uses a PWM controlled TCC so you don't notice the lockup like the Rodeo On/Off TCC.
 

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Discussion Starter · #8 ·
Thank you sir! I guess I was worried about nothing. I just wanted this truck to be good to go again. We really need this truck, and my wife has been missing it dearly these last couple of months.
Now I can focus back on the ABS light that won’t go away, and a random miss-fire code that comes and goes. Then there’s the disc brake rear end I’ve been wanting to get swapped out too. I hate drum brakes!
 
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