What Does B1606 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground in the anti-theft indicator lamp circuit. The circuit that controls the security/theft warning light on the instrument cluster is drawing current through an unintended ground path, causing excessive current flow. This typically occurs when damaged wiring insulation allows the positive circuit to contact vehicle chassis ground or when internal lamp/module failure creates a ground fault.
Common Causes
45%
Damaged or chafed wiring harness causing short to ground between BCM and anti-theft indicator lamp
25%
Failed anti-theft indicator lamp or LED assembly with internal short to ground
20%
Corroded or moisture-damaged connector terminals at instrument cluster or BCM creating ground path
10%
Failed Body Control Module with internal driver circuit short to ground
Diagnostic Steps
1
Step 1: Perform visual inspection of instrument cluster wiring harness from BCM to cluster, checking for pinched, chafed, or damaged wires especially near metal edges, hinges, and routing clips. Look for signs of previous repairs or aftermarket installations.
2
Step 2: Disconnect the instrument cluster connector and measure resistance from the anti-theft indicator lamp circuit pin (identified via wiring diagram) to chassis ground with a digital multimeter. Should read open circuit (OL); any measurable resistance below 10k ohms indicates a short to ground in the wiring or lamp.
3
Step 3: If Step 2 shows short, disconnect BCM connector and repeat resistance measurement from lamp circuit wire to ground. If short disappears, BCM internal fault is confirmed. If short remains, fault is between BCM and cluster connectors.
4
Step 4: Inspect all connectors for corrosion, pushed-out pins, or moisture intrusion. Clean connectors with electrical contact cleaner and apply dielectric grease. Check connector pin tension and repair/replace as needed.
5
Step 5: If wiring checks good, substitute known-good instrument cluster or lamp assembly to verify internal lamp short. Many clusters have separate lamp boards that can be replaced without full cluster replacement.
6
Step 6: After repair, clear codes, cycle ignition and security system multiple times, and verify anti-theft lamp operates normally during bulb check and security arming/disarming sequences.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground in the anti-theft indicator lamp circuit. The circuit that controls the security/theft warning light on the instrument cluster is drawing current through an unintended ground path, causing excessive current flow. This t...
The most common cause of B1606 (Lamp Anti-Theft Indicator Circuit Short To Ground) is: Damaged or chafed wiring harness causing short to ground between BCM and anti-theft indicator lamp
Typical repair costs for B1606 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects the anti-theft indicator lamp functionality. The anti-theft system may still function normally for immobilization, but the driver will lack visual feedback of system status, which could lead to unexpected no-start conditions if security system is armed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1606 to identify the root cause.
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Quick Info
Category
Body
System
Anti-Theft/Security System
Difficulty
Type
Manufacturer
Recommended Tools
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