C0090

Step 1: Perform visual inspection of all wiring and connectors from ABS control module to right rear wheel area, looking for chafing, corrosion, water intrusion, or damaged insulation. Pay special attention to flex points near suspension and wheel well.

Step 2: Using a digital multimeter, measure resistance across the right rear ABS solenoid valve terminals (typically 3-8 ohms). Compare reading to manufacturer specifications to verify solenoid coil integrity.

Step 3: Disconnect ABS control module connector and inspect pins for corrosion, pushed-back terminals, or damage. Check for continuity between the solenoid valve connector and ABS module connector pins (should be less than 1 ohm). Also check for shorts to ground or power (should be infinite resistance).

Step 4: With module disconnected, measure voltage supply to the ABS solenoid circuit to verify proper power and ground signals from the module side using wiring diagram reference. Typical supply voltage is battery voltage when activated.

Step 5: If all wiring and resistance checks pass, perform a solenoid activation test using the scan tool's bidirectional controls to command the right rear solenoid on/off. Listen and feel for solenoid clicking at the HCU. Lack of operation indicates HCU or module failure.

Step 6: Clear codes, road test vehicle with multiple ABS activation events, and monitor for code return. If code returns immediately with good wiring, replace ABS hydraulic control unit or control module based on previous test results.