B1751

Step 1: Perform visual inspection of the transmission range sensor connector and wiring harness for obvious damage, chafing against exhaust/frame, corrosion, or pin damage. Pay special attention to areas where harness routes near sharp edges or heat sources.

Step 2: Disconnect the transmission range sensor connector and use a digital multimeter to measure voltage on the signal wire(s) at the harness side connector with ignition ON. Reading should be 0V or reference voltage (typically 5V), NOT battery voltage (12V+). If battery voltage is present, there is a short to power in the harness.

Step 3: With connector still disconnected, measure resistance between the signal wire and battery positive at the harness side. Reading should be infinite (open circuit). Low resistance indicates a short to power in the wiring between sensor and control module.

Step 4: If harness tests good, inspect the transmission range sensor itself. With sensor disconnected, check for abnormal resistance values or shorts between sensor terminals using manufacturer specifications. Typical sensors show varying resistance based on gear position.

Step 5: Reconnect all components and clear codes. Cycle the transmission through all gear positions while monitoring live data for proper park/neutral switch state changes. Verify code does not immediately return and that starter only engages in Park/Neutral positions.

Step 6: If all wiring and sensor tests pass but code persists, suspect control module fault. Test control module connector for corrosion or damaged pins, and verify proper ground circuits before considering module replacement.