B1627: Reverse Input Circuit Malfunction
Diagnostic trouble code B1627 indicates a fault in the reverse input circuit of the transmission range sensor (TRS) or PRNDL position sensor. This sensor monitors the gear selector position and sends signals to the powertrain control module (PCM) or body control module (BCM). The fault occurs when the reverse input circuit fails to provide the expected electrical signal due to an open circuit, short to ground or voltage, or erratic signal. In Ford vehicles, this code is typically associated with the transmission range sensor mounted on the steering column or console. When this code sets, the control module cannot verify reverse gear position, which may affect reverse lights, backup camera, navigation, and transmission control logic.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty or worn PRNDL position sensor
- Damaged, corroded, or loose wiring in the reverse input circuit
- Short to ground or voltage in the reverse signal circuit
- Open circuit in the wiring harness between sensor and control module
- Sensor connector contaminated with moisture, oil, or corrosion
- Internal failure of the PCM or BCM processing the signal
- Incorrect adjustment of the transmission shift linkage cable
3. Symptoms You Will Notice
- Reverse lights not working
- Backup camera or navigation system not engaging in reverse
- Transmission shifting issues or erratic behavior
- Check Engine Light or transmission warning light illuminated
4. Step-by-Step Diagnosis
Scan for additional codes and verify B1627 is present
Inspect the PRNDL sensor connector and wiring for damage, corrosion, or loose connections
Test the reverse input circuit for continuity, shorts, and proper voltage using a multimeter
Check the transmission range sensor adjustment and replace if necessary
If wiring and sensor are okay, test the PCM/BCM for proper signal processing
5. Frequently Asked Questions
Is it safe to drive?▼
It is generally safe to drive short distances, but you may experience issues with reverse lights, backup camera, or transmission shifting. It is recommended to diagnose and repair the issue promptly to avoid potential transmission problems.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, depending on whether the sensor or wiring needs replacement. Labor costs vary by shop and vehicle model.