B1606: Anti-Theft Indicator Circuit Short to Ground
The B1606 code indicates that the Body Control Module (BCM) or Powertrain Control Module (PCM) has detected a short to ground in the control circuit for the anti-theft system indicator lamp (security light in the instrument cluster). This fault prevents the PATS (Passive Anti-Theft System) from providing visual feedback to the driver, leaving them unaware of the immobilizer status. The issue is typically caused by a wiring short, a faulty LED or bulb in the cluster, a damaged BCM driver, or corroded connectors.
1. Commonly Affected Makes
2. Most Common Causes
- Wiring in the anti-theft indicator circuit shorted to ground (chassis)
- Defective Body Control Module (BCM) with damaged internal driver
- Corroded, dirty, or damaged connectors at the instrument cluster or BCM
- Internal short circuit within the instrument cluster
3. Symptoms You Will Notice
- Security light (anti-theft indicator) stays on constantly or does not illuminate
- No visual indication of PATS system status (armed/disarmed)
- Possible no-start condition if the immobilizer is active and not recognized
4. Step-by-Step Diagnosis
Scan for B1606 and other related codes using a compatible diagnostic tool
Visually inspect the anti-theft indicator circuit wiring for shorts to ground or damage
Test the security light bulb/LED in the instrument cluster for continuity and shorts
Check connectors at the BCM and instrument cluster for corrosion, bent pins, or poor contact
If wiring and bulb are okay, suspect a faulty BCM and perform further module testing
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but the vehicle may not start if the PATS immobilizer is active and the fault prevents proper communication. It is recommended to diagnose and repair the issue promptly to avoid being stranded.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause. A simple wiring repair or bulb replacement may be under $150, while BCM replacement can exceed $300 including programming.