kick down cable not rusted stuck fully out and TH thinks you are passing other cars WOT?
no engine told, of 4 offered day1 new. even a diesel.
1989 oem stock THM-400? NO./
4.3L guessed
full trans code is 1989 !
THM700-R4/4L60/MD8 (4 speed is stock)
TH400 is 3speed not 4. ,now called 3L80 and ended in 1979 ,
but is really 1989 1971-1994
3L80HD (heavy duty version of TH400)<< yes
i just looked in the service manual
it shows this box
THM 700R4 transmission. or TH400/3L80HD
and shows
Throttle Valve (TV) or Detent Cable
one must not lose vacuum to the modulator of the transmission see 100% engine overload, and wants to use lower gears, so the vacuum must be there
and MOD is color coded, and must not be ignored, it must match the weight of the car or it will not shift correctly. Do not use the wrong MOD ever.
this is not a 4L80E/3L80E box no electric shifts. yes TCC lockup. sure.
TCC relay is ECM controlled. clutch main TC lockup. acts like gear 3.5.
A tuneup does not effect THM turbo hydra matic. box.
unless huge engine power loss subsequent vacuum now wrong.
the box shift, itself.
only mod and TV cable and full engine power,changes it and for sure
the GOVERNOR.
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