What Does B1689 Mean?
This code indicates the Body Control Module (BCM) has detected a malfunction in the automatic headlamp delay circuit, which controls the amount of time headlamps remain illuminated after the vehicle is turned off. The BCM monitors this circuit for proper voltage, resistance, and circuit continuity. When an abnormal condition is detected in the delay timer circuit or its control path, this code is set.
Common Causes
35%
Faulty autolamp delay relay or timer module
30%
Damaged or corroded wiring/connectors in the autolamp delay circuit
20%
Malfunctioning Body Control Module (BCM)
15%
Faulty headlamp switch with integrated delay function
Diagnostic Steps
1
Step 1: Perform visual inspection of all wiring and connectors associated with the autolamp delay circuit, checking for corrosion, loose connections, damaged pins, or chafed wires near the BCM, headlamp switch, and delay relay location
2
Step 2: Using a digital multimeter, verify power supply (typically battery voltage) and ground integrity at the autolamp delay relay or module connector with ignition on, comparing readings to manufacturer specifications
3
Step 3: Test the autolamp delay relay by measuring coil resistance (typically 70-100 ohms) and performing a bench test by applying appropriate voltage to verify relay clicking and continuity through contacts
4
Step 4: Monitor live data from the BCM using the scan tool to observe autolamp delay timer status, input signals from the headlamp switch, and output commands to verify proper communication and control logic
5
Step 5: If all previous tests pass, swap the suspected relay/module with a known good unit or test the headlamp switch delay function by measuring resistance values through various switch positions
6
Step 6: Clear codes, cycle the autolamp delay function through its complete operation (engine off, doors closed/opened), and verify the repair by confirming proper headlamp delay operation and no code return
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a malfunction in the automatic headlamp delay circuit, which controls the amount of time headlamps remain illuminated after the vehicle is turned off. The BCM monitors this circuit for proper voltage, resistance, and circuit continuity. ...
The most common cause of B1689 (Autolamp Delay Circuit Failure) is: Faulty autolamp delay relay or timer module
Typical repair costs for B1689 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is safe to continue driving as it only affects the convenience feature of delayed headlamp shut-off after exiting the vehicle. The headlamps will still function normally for driving purposes, but may not remain on after the vehicle is turned off, which could reduce visibility when exiting in dark conditions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1689 to identify the root cause.
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Quick Info
Category
Body
System
Exterior Lighting System
Difficulty
Type
Manufacturer
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