Diagnostic Aids
WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
If an intermittent is suspected, see INTERMITTENT TROUBLE CODE DETERMINATION under ON-BOARD DIAGNOSTICS under SELF-DIAGNOSTIC SYSTEM.
Electromagnetic Interference (EMI) from ignition coil or from spark plug wires could cause a faulty signal condition in CMP signal circuit to PCM. Ensure routing of CMP circuitry is correct.