Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
If the glow plug relay is stuck in the ON position, check for proper operation of the glow plugs, perform Glow Plug System Diagnosis. See appropriate SYSTEM & COMPONENT TESTING article. When glow plugs are commanded ON by the scan tool, an internal PCM timer protects the glow plugs from damage by cycling them ON for 3 seconds and then OFF for 12 seconds.
The glow plug output feed wire nut and battery feed wire nut at the relay should be checked for proper torque, 44 INCH lbs. (5 N.m) and for corrosion.
An intermittent may be caused by the following:
- Poor connections.
- Rubbed through wire insulation.
- Broken wire inside the insulation.