Automatic Headlights stopped working - Resolved, my error.

[HarryD]

Up to just now, with 90,000 miles, the headlights have been operating in Automatic Mode with no issue.
They just stopped working, and my first assumption was that the light sensor on the dash stopped working, but the lights stopped turning on when the windshield wipers were on as well.
When operating the windshield wipers, the headlights would turn on after a short (maybe 10 seconds) delay even if it was not dark enough for the light sensor to turn the headlights on.
Any thoughts?

Sponsored

 

[RangerBill]

Up to just now, with 90,000 miles, the headlights have been operating in Automatic Mode with no issue.
They just stopped working, and my first assumption was that the light sensor on the dash stopped working, but the lights stopped turning on when the windshield wipers were on as well.
When operating the windshield wipers, the headlights would turn on after a short (maybe 10 seconds) delay even if it was not dark enough for the light sensor to turn the headlights on.
Any thoughts?

Is the windshield in front of the camera near the rearview mirror clean? That camera is used to switch high and low beams when in autolamp headlight mode. Check for any DTC codes with a code scanner that reads all codes (not just powertrain codes).

 

[Big Blue]

Which of the Auto Headlight functions are not working? There are several, and they all have different conditions to activate. I agree with @RangerBill . Check for DTCs. There maybe one set that does not trip the CEL. Maybe clearing it will get you functioning again.

 

[HarryD]

Thank you for these insights. I do not use the Auto Hi-Beams (selected Off).
Sensor and windshield camera areas are clean. I did not think to check for codes-Good Call. I will try that.

 

[airline tech]

Yes - You will need to check for codes to see which half of the circuit is faulting.

Switch - (Switch to BCM)
Sun load Sensor (Sensor to BCM) & (FCIM)

The SCCM (Wiper) input - requires the (Auto-Lamp) circuit to be operational.

 

[HarryD]

I was able to check for codes tonight, and my code reader shows no Diagnostic Trouble Codes were stored.

 

[RangerBill]

I was able to check for codes tonight, and my code reader shows no Diagnostic Trouble Codes were stored.

Does your code reader read all codes? You might want to download Forscan and purchase the recommended OBDII adapter to be able to read all modules in the truck. Many readers only powertrain DTCs.

Sponsored