With RPO C60/C67/CJ3

1. (VIN M) Check ENG EMIS Fuse. If open, check CKT 241, CKT 459 and CKT 59 for a short to ground. (VIN L, X) Check CRUISE Fuse. If open, check CKT 739, CKT 459 and CKT 59 for a short to ground.
2. Check that ground G117 is clean and tight.
3. Check A/C Compressor Clutch Connector terminals for corrosion.
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (refer to General Troubleshooting Procedures). Diagnostic Aids
^ Refer to System Diagnosis. With RPO C60/C67/CJ3