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**pjmoreland** · 11-03-2022, 02:57 PM

I purchased a 1989 K1500 recently that has a 700R4. It has been interesting to observe the behavior of the TCC lockup logic. Under light acceleration, it seems to lock the TCC at quite a low speed, like around 35MPH. It does unlock it quite readily with increased acceleration though. Personally, I prefer having the TCC lock at speeds over 45MPH, as it lugs the engine less that way. Also, I could be wrong, but it seems to lock the TCC even if I have shifted manually to "D" (third gear). Also, the TCC seems to unlock when coasting.

11-03-2022, 02:57 PM	#138
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,349	Re: 700R4 TCC Wiring I purchased a 1989 K1500 recently that has a 700R4. It has been interesting to observe the behavior of the TCC lockup logic. Under light acceleration, it seems to lock the TCC at quite a low speed, like around 35MPH. It does unlock it quite readily with increased acceleration though. Personally, I prefer having the TCC lock at speeds over 45MPH, as it lugs the engine less that way. Also, I could be wrong, but it seems to lock the TCC even if I have shifted manually to "D" (third gear). Also, the TCC seems to unlock when coasting.