Diagnostic Aids
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Do not replace the torque converter for this condition.
Inspect wiring for poor connections at PCM, transaxle in-line 20-pin harness connector and TFP manual valve position switch. Check for bent, backed out or damaged terminals, or poor terminal tension. Check for chafed wire or broken wire inside insulation. Check for moisture and corrosion in wiring and connections. When diagnosing intermittent condition, wiggle wiring harness while watching scan tool for change in value.