B1351: Key-In Sense Circuit Short to Battery
The Body Control Module (BCM) or Smart Junction Box (SJB) has detected battery voltage on the key-in sense circuit when the key is not in the ignition cylinder. Normally, this circuit is grounded or open with the key removed. The presence of battery voltage indicates a fault in the key-in switch, wiring, or the module itself, preventing proper operation of systems such as the key-in reminder chime, door locks, and the Passive Anti-Theft System (PATS).
1. Commonly Affected Makes
2. Most Common Causes
- Key-in switch internally shorted to battery positive
- Key-in sense circuit wiring shorted to battery voltage (B+)
- Damaged connectors or terminals bridging to power circuits
- Internal BCM/SJB failure in the circuit monitoring driver
3. Symptoms You Will Notice
- Key-in reminder chime stays on or behaves erratically
- Door locks may not operate correctly
- PATS (anti-theft) system may malfunction or prevent starting
- Possible battery drain if circuit remains powered
4. Step-by-Step Diagnosis
Check for battery voltage on the key-in sense wire with key removed; if present, suspect a short to B+.
Inspect the key-in switch for internal short; test switch continuity with key in and out.
Visually examine wiring and connectors for damage, corrosion, or pinched wires near the ignition cylinder.
If wiring and switch are okay, suspect a faulty BCM/SJB and perform module self-test or replacement.
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but the vehicle may have issues with door locks, chimes, or the anti-theft system. It's best to diagnose and repair soon to avoid potential battery drain or starting problems.
How much does it cost to fix?▼
Typically $100–$300 for switch or wiring repair; if the BCM/SJB needs replacement, costs can range from $500–$1,200 including labor.