C0655

Step 1: Locate the level control compressor relay (typically in underhood fuse/relay box) and perform visual inspection of relay, connector terminals, and wiring for corrosion, damage, or burned contacts. Remove and inspect relay for physical damage or burn marks.

Step 2: Using a digital multimeter, test relay coil resistance across control terminals (typically 80-120 ohms) and verify continuity through switched contacts when relay is manually activated. Replace relay if out of specification.

Step 3: With relay removed, check for battery voltage at relay power supply terminal (key on) and verify ground circuit continuity at relay control terminal using multimeter (should be less than 1 ohm to known good ground).

Step 4: Back-probe the relay control wire from the suspension control module while commanding compressor activation via scan tool active tests. Verify module is switching ground on/off (should pulse between 0V and battery voltage). If no switching occurs, suspect module failure.

Step 5: Inspect and clean all ground connections for suspension system components, including module ground and relay ground. Verify less than 0.5 ohm resistance to battery negative terminal.

Step 6: After repairs, clear codes and perform active test of compressor operation through scan tool to verify relay clicks and compressor runs. Road test vehicle and verify system maintains proper ride height without code return.