B1690: Autolamp Delay Circuit Open
The B1690 code indicates that the Body Control Module (BCM) or Generic Electronic Module (GEM) has detected an open circuit in the autolamp delay control line. This circuit manages the timing that keeps the headlights on after the ignition is turned off. An open circuit prevents the module from properly controlling the delay function, which can cause the lights to stay on permanently or become inoperative in automatic mode.
1. Commonly Affected Makes
2. Most Common Causes
- Open circuit in wiring or connector between the headlamp switch/BCM and the headlight relay
- Faulty headlamp switch (internal open)
- Damaged Body Control Module (BCM/GEM)
- Blown fuse in the delay power supply circuit
- Poor ground connection at the module or switch
3. Symptoms You Will Notice
- Headlights stay on continuously after ignition off
- Autolamp (automatic headlight) feature does not work
- Headlights do not turn on in automatic mode
- Battery drain due to lights left on
4. Step-by-Step Diagnosis
Check for blown fuses related to the autolamp delay circuit
Inspect wiring and connectors for damage, corrosion, or loose connections between the headlamp switch, BCM, and headlight relay
Test the headlamp switch for continuity and proper operation
Verify ground connections at the BCM and headlamp switch are clean and tight
If all else is good, test or replace the BCM/GEM
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but the headlights may not function correctly in automatic mode or may stay on, draining the battery. It is safe to drive with manual headlight control, but have the issue diagnosed soon.
How much does it cost to fix?▼
Typically $100–$300 for diagnosis and repair, depending on the cause. A faulty headlamp switch or wiring repair is on the lower end; BCM replacement can cost $400–$800 or more.