Had the engine tune up know i lost 2/3 gear at any rpm fluld good elec sol hooked up all vac lines hooked up new mod just in case was working fine before work on engine and every thing is hooked up ck 4 times still no 2/3 gear great rev & 1st also changed fluid filter was clean pick up tobe ok also
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.
SOURCE: What model transmission is on my 92 4x4 Suburban 5.7 1500. (350)
Output shaft is generally a different lenght on the 2wd vs the 4wd.
SOURCE: slight miss in engine, hard shift from 1st to 2nd long 2nd gear
Check both O2 sensor(s) and catalytic coverter.. P0420 means catalyst below threshold. Also check the sensor at the transmission and solenoid.
SOURCE: Automatic Transmission shifts late and rough after warm
AS YOUR CAR IS VERY OLD. THE ENGINE PARTS MUST BE VERY OLD. IN THIS SITUATION EVERY CAR DOSENT WORKS PROPER WHEN THE ENGINE BECOMES HOT. YOU JUST NEED TO CHECK AT CHEVY SERVICE CENTER FOR A BETTER SOLUTION. THEY WILL HELP U BETTER AFTER CHECKING YOUR CAR PERSONALLY.
PLS. RATE MY SOLUTION.
NICE DAY
KETAN
SOURCE: 1997 chevy k1500 pickup-transmission shifting problems
check the fluid level in the transmission, also change the transmission fluid and filter
SOURCE: 01 duramax allison changed fluid and filters now in limp mode
Make sure you have the proper amount of tranny fluild in it and get that Valvoline fluid out of it. Allison transmissons have there own type of tranny fluid and you want to use it. You can buy the right stuff from a Allison dealer. Most Detroit Diesel dealers are also Allison dealers. Look them up in your phone book and they will tell you the quanity and sell you five gallon pails of the fluid. Just get the serial number off of the side of the transmisson before you call. Change the fliters again too. Believe me, this is important. My company has Yard horses with Allison transmissions and you don't want to screw with the small stuff. Service them right and they work as hard as you want.
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