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Discussion Starter · #1 ·
I am having trouble (PCM?) shifting and staying in 4th, it is behaving almost like it is in "Performance mode", but there is no performance mode on this car (see background).

Symptoms: have to be above 55 and foot nearly off throttle to get 4th. With even a small amount of throttle (20%), down shifts to 3rd.

PCM command is accurate, so I believe the problem is in the PCM or ?? did I miss a wire?

Background:
1994 Caprice LT1, 4L60E, Engine Swapped into Toyota Land Cruiser
PCM Speedometer corrected for new axle gearing (no other changes to PCM)
Speed Verified on Scanner
Gear Command Verified on Scanner
 

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Shift logic can also be changed in the PCM. I have similar engine, trans in an 84 El Camino and changed rear axle to 3.42. In addition to resetting axle ratio in PCM, I also had shop tweak the 1-2 shift point.
 

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Discussion Starter · #4 ·
If anyone stumbles across this... the problem was due to Cruise signal. The ECM thought the car was in "cruise" mode, and was using the cruise shift tables. SOLUTION: change the cruise shift tables to match normal mode, or find the super top-secret place the ECM gets its "cruise" signal from. I have been unable to locate documentation on how the cruise signal is passed to the ECM.
 
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