Autolamp Output Circuit Failure B1693
The B1693 code indicates that the Body Control Module (BCM) or Lighting Control Module (LCM) has detected a fault in the Autolamp output circuit. This means the module cannot properly activate the headlights in automatic mode due to an open circuit, short to ground, or internal failure of the module's output driver.
1. Commonly Affected Makes
2. Most Common Causes
- Open or short-to-ground in the Autolamp output circuit wiring or connector
- Faulty headlamp relay or damaged relay control circuit
- Internal failure of the BCM or LCM output driver
- Blown fuse in the headlamp relay power supply circuit
- Defective headlamp switch if it provides input signal to the BCM
3. Symptoms You Will Notice
- Automatic headlights do not turn on or off as expected
- Headlights may stay on constantly or fail to illuminate in auto mode
- Check Engine Light or Service Lamp warning on the dashboard
4. Step-by-Step Diagnosis
Scan for codes and verify B1693 is present
Inspect the Autolamp output circuit wiring and connectors for damage, corrosion, or shorts
Test the headlamp relay and its control circuit for proper operation
Check the relevant fuse in the headlamp relay power circuit
If all external circuits are good, suspect internal BCM/LCM failure and perform module self-test or replacement
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but automatic headlight function will be impaired. You may need to manually operate the headlights. The issue is moderate and should be repaired soon to ensure proper lighting.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause. Wiring repairs are cheaper, while BCM/LCM replacement can be more expensive.