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. 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. Check for wires broken inside their insulation. If diagnosing for intermittent short or open conditions, move wiring harness while observing scan tool for value changes.
If all of the PRNDL indicators are inaccurate, ensure that the park/neutral position switch is properly adjusted.
TRANSMISSION RANGE SWITCH LOGIC (1)
| Gearshift Lever Position | Signal "A" | Signal "B" | Signal "C" | Signal "P" | ||
|---|---|---|---|---|---|---|
| Park | LOW | HI | HI | LOW | ||
| Reverse | LOW | LOW | HI | HI | ||
| Neutral | HI | LOW | HI | LOW | ||
| "OD" | HI | LOW | LOW | HI | ||
| "3" | LOW | LOW | LOW | LOW | ||
| "2" | LOW | HI | LOW | HI | ||
| "1" | HI | HI | LOW | LOW | ||
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