Rebuilt 4L60e installed, does not shift properly?

2003 CHEVROLET S-10
128,955 MILES • 4.3L • V6 • 4WD • AUTOMATIC
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TWOZR2
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2003 S10 ZR2 4.3 Auto 4L60e. Transmission has been replaced with a remanufactured unit from Powertrain Products. It does not shift properly. Start truck put in D starts off in L shifts to 2 hard at a higher RPM than expected. Doesn't shift any further. Let off gas and it acts like it goes to N. RPMs drop like in N. Get on the accelerator RPMs rise to 2nd gear road speed before engagement. Never shifts to D or OD. Won't shift out of 2 up or down. Starts off in 2 and stays in 2. Manually put in L1 stays in 2. The speedometer doesn't work. Transfer case output VSS has been replaced with a new one. Here's a list of codes: P0502, P0507, C0236, B0036, U1000, U1096, and U1064. Basically, it behaves like a 2-speed transmission at first takeoff, then never leaves 2nd. Reverse is operating fine.
Apr 26, 2023 at 9:05 AM
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STRAILER
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Here are the code definitions:

P0502: This code indicates a problem with the Vehicle Speed Sensor (VSS) circuit,

P0507: This code indicates a problem with the Idle Control System,

C0236: This code indicates a problem with the rear wheel speed sensor circuit,

B0036: This code indicates a problem with the Airbag System, specifically the driver-side airbag circuit.

U1000: This code indicates a communication fault in the network between various control modules in the vehicle.

U1096: This code is similar to U1000 and indicates a communication fault in the network between various control modules

U1064: This code is also similar to U1000 and U1096, but is more specific to the Body Control Module (BCM).

These codes can be caused by a bad ground, I would recheck the grounds on the transmission bellhousing to make sure they were connected when the unit was installed. Also, double check the electrical connector on the transmission itself. Please let us know what you find.
Apr 27, 2023 at 3:06 PM
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TWOZR2
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I'm going to check those grounds for sure, especially being 20 years old. One confusing thing is that the scanner I have, Zurich ZR13S, specifically pointed out: Left rear speed sensor signal missing quote unquote for code C0236. There are no left or right rear speed sensors. From what I have found is the VSS on the transfer case output is the only sensor monitoring the rear. I replaced it and still no improvement and still getting the same codes. It was suggested that the problem may lie in the instrument cluster. I have access to a'98 ZR2 Blazer with the same cluster. Maybe switch the two and see what happens.
Apr 27, 2023 at 7:33 PM
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STRAILER
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Yep, that could be the problem. Here is a guide to help check the wiring diagrams for the transmission which are below:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Please let us know what happens.
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Apr 29, 2023 at 11:03 AM