What Does B1589 Mean?
This code indicates the Body Control Module (BCM) has detected a short to battery voltage in the autolamp delay increase circuit. The autolamp system automatically controls exterior lighting based on ambient light conditions and includes a delay feature that keeps lights on for a set period after the vehicle is turned off. The BCM detected unwanted battery voltage present on the control circuit for the delay increase function, meaning the circuit is receiving constant power when it should be controlled.
Common Causes
45%
Damaged or chafed wiring harness causing short to power in the autolamp delay circuit between BCM and headlamp switch or relay
30%
Faulty headlamp switch assembly with internal short to battery voltage on delay increase circuit
15%
Corroded or damaged connector terminals at BCM or headlamp switch causing cross-circuit short
10%
Failed Body Control Module with internal short circuit on autolamp delay output driver
Diagnostic Steps
1
Step 1: Perform visual inspection of wiring harness from BCM to headlamp switch, focusing on areas where harness passes through firewall, door jambs, or near sharp edges. Look for damaged insulation, pinched wires, or evidence of previous repairs
2
Step 2: Disconnect the headlamp switch connector and use a digital multimeter to measure voltage on the autolamp delay increase circuit pin at the harness side with ignition on. Reading should be 0V; if battery voltage is present, the short is in the harness between BCM and switch
3
Step 3: If no voltage found at switch connector, reconnect switch and disconnect BCM connector. Measure resistance between the autolamp delay circuit pin and battery positive at the BCM harness connector. Reading should be open circuit (OL); any continuity indicates short to power in harness
4
Step 4: Inspect BCM and headlamp switch connectors for corrosion, pushed-out pins, or contamination. Clean with electrical contact cleaner and check for proper terminal tension. Check adjacent circuits for cross-contamination or melted connector housing
5
Step 5: If harness tests good, substitute known-good headlamp switch to verify if internal switch failure is causing short. Monitor for code recurrence with replacement switch installed
6
Step 6: Clear codes and verify repair by cycling autolamp delay function multiple times and road testing. Monitor live data for proper voltage control on delay circuit during operation
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to battery voltage in the autolamp delay increase circuit. The autolamp system automatically controls exterior lighting based on ambient light conditions and includes a delay feature that keeps lights on for a set period after th...
The most common cause of B1589 (Autolamp Delay Increase Circuit Short To Battery) is: Damaged or chafed wiring harness causing short to power in the autolamp delay circuit between BCM and headlamp switch or relay
Typical repair costs for B1589 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this affects only the delayed shutoff feature of automatic headlamps, not core lighting functionality. Repair at convenience, though lights may not turn off automatically after exiting vehicle, potentially draining the battery if left unattended for extended periods.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1589 to identify the root cause.
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Quick Info
Category
Body
System
Exterior Lighting Control System
Difficulty
Type
Manufacturer
Recommended Tools
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