What Does B1690 Mean?
B1690 indicates the Body Control Module (BCM) has detected an open circuit in the autolamp delay system. This system controls the automatic headlight shutoff feature that keeps exterior lights illuminated for a preset time after the ignition is turned off. The BCM has identified a break in continuity within the delay circuit wiring, relay, or module connections.
Common Causes
35%
Open or corroded wiring in the autolamp delay circuit between BCM and headlamp relay
30%
Failed autolamp relay or poor relay socket connection
20%
Damaged or disconnected BCM connector affecting autolamp delay circuit
15%
Failed BCM internal autolamp delay driver circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of autolamp relay (typically in underhood fuse/relay box) - check for proper seating, corrosion, or damaged socket contacts. Remove and inspect relay pins for burning or corrosion
2
Step 2: Using a digital multimeter, check for battery voltage at relay socket power supply terminal with ignition on. Verify ground circuit continuity (should read less than 0.5 ohms to chassis ground)
3
Step 3: Locate BCM connector (usually under dash or behind kick panel) and inspect for water intrusion, corrosion, or pushed-back pins. Check wiring harness from BCM to headlamp relay for chafing, breaks, or rodent damage
4
Step 4: Using wiring diagram for specific vehicle, backprobe BCM connector autolamp delay output circuit and measure voltage/continuity while commanding autolamp system on via scan tool active tests (if available). Should see switching voltage (typically 0V to 12V)
5
Step 5: If all wiring and relay check good, substitute known-good relay to verify. If problem persists, measure resistance of circuit from BCM to relay control terminal (should be less than 5 ohms)
6
Step 6: After repairs, clear code, cycle ignition off and verify autolamp delay functions properly (lights remain on for programmed duration then shut off). Re-scan to confirm no code returns
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
B1690 indicates the Body Control Module (BCM) has detected an open circuit in the autolamp delay system. This system controls the automatic headlight shutoff feature that keeps exterior lights illuminated for a preset time after the ignition is turned off. The BCM has identified a break in continuit...
The most common cause of B1690 (Autolamp Delay Circuit Open) is: Open or corroded wiring in the autolamp delay circuit between BCM and headlamp relay
Typical repair costs for B1690 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. This only affects the convenience feature that keeps headlights on briefly after exiting the vehicle. Headlights will still function normally with manual or automatic control during driving. Repair at convenience to restore autolamp delay functionality.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1690 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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