Diagnostic Aids
WARNING: This page is about a different car, the 2002 GMC Cab & Chassis Sierra and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Inspect wiring for poor connections at PCM and at transmission in-line 20-way harness connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wires that could short to bare metal or other wiring. Inspect for wires broken inside their insulation. If diagnosing for intermittent short or open conditions, move wiring harness while observing scan tool for value changes.
DTC P0758 defaults to an elevated line pressure condition which may result in TCC partial apply. This may induce idle surge and engine stall. See SHIFT SOLENOID VALVE STATE & GEAR RATIO table under DESCRIPTION & OPERATION.