p0740 code looks like a wiring problem or mechanical?

2000 CHEVROLET ASTRO
220,000 MILES • 4.3L • 6 CYL • 4WD • AUTOMATIC
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MGLSITE
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Ran a live data scan in trans and this is what I got.
TCC Enable No
TCC Mode 0
TCC Duty Cycle 95
TCC Slip Speed 345
TCC Brake Switch Closed
TCC Duty Cycle open/short to ground No
TCC Duty Cycle Short to voltage No
TCC Enable open/short to ground Yes
TCC Enable short to voltage No

I was wondering if this looks like a wiring problem or mechanical


Thanks
Nov 17, 2025 at 10:05 AM
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STRAILER
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This seems like an electrical problem, specifically the torque converter control solenoid which is bad and shorted or the wiring inside the transmission is shorting to the case or you have a shorted tog round exterior wire from the PCM but chances are the solenoid is bad and need to be replaced.

TCC Enable: NO
The PCM is not commanding the torque converter clutch to lock.

TCC Duty Cycle: 95%
PCM is trying HARD to apply the TCC (95% command = full apply).

TCC Slip Speed: 345 RPM
The clutch is not locking, tons of slip.
But this could be because the apply circuit never actually energizes.

Brake Switch: CLOSED
This means the PCM thinks the brake pedal is being pressed.

TCC Enable open/short to ground: YES
This is the problem.
The PCM sees a fault in the electrical circuit that enables TCC apply.

Please let us know what happens.
Nov 18, 2025 at 11:00 AM