B1628

Step 1: Perform a visual inspection of the transmission range sensor connector and wiring harness near the transmission for damage, corrosion, loose connections, or broken wires. Check connector pins for corrosion, bent pins, or pushed-back terminals.

Step 2: Using a digital multimeter, backprobe the reverse position switch signal wire at the transmission range sensor connector while shifting into reverse. Verify continuity and proper voltage signal (typically 0V in park/neutral, 5V or 12V in reverse depending on manufacturer). Compare readings to other PRNDL positions.

Step 3: Disconnect the transmission range sensor connector and test for continuity across the reverse position terminals of the sensor itself while manually moving the shift linkage to reverse position. Sensor should show continuity (closed circuit) in reverse, open circuit in all other positions.

Step 4: Trace and inspect the wiring from the transmission range sensor to the BCM/TCM connector, checking for opens, shorts to ground, or shorts to power using a multimeter. Pay special attention to areas where wiring passes through the firewall or near heat sources.

Step 5: If wiring and sensor test good, check the BCM/TCM connector terminals for damage or corrosion. Measure resistance of the entire circuit from sensor to module with both ends disconnected (should read less than 5 ohms).

Step 6: Clear codes, test drive the vehicle through all gear positions multiple times, and verify the code does not return. Confirm backup lights, reverse warning systems, and all PRNDL-related functions operate correctly.