LS left headlight stays on and wont go off

[dfwlincoln]

My left headlight stays on and wont go off unless I unplug at the headlight assembly. Does anyone have a clue what to do on this?

 

[lseguy]

Im going to guess a faulty headlight switch. Only a voltmeter will give you more specific info.

 

[97stscaddy]

Not sure how the headlights are wired in these, but seeing that only one side has the problem, im gonna say its a stuck relay.

What year is the car? Does it have HIDs?

 

[dfwlincoln]

2005 and it is halogen

 

[owlman]

Here's the diagnostic flow for your problem from the service manual (2006). :shifty:

 

[97stscaddy]

The instrument cluster monitors the headlamp switch position. When the headlamp switch is in the HEADLAMPS ON position, the instrument cluster sends a message to the front electronic module (FEM) to illuminate the headlamps. If a problem is detected with the circuits to the headlamp switch, the instrument cluster defaults the headlamps on. The FEM controls the ground circuit for each halogen bulb or high intensity discharge (HID) relay (if equipped). If a problem is detected with any of the signal circuits to the headlamp switch, the instrument cluster defaults the parking lamps and headlamps on. The FEM controls the ground for the headlamp bulbs (and the HID relays, if equipped).

Jeez, this electronic crap is a PITA... all just so it will tell you when you've got a bulb out.
At least they had the sense to make the light stay ON when something is wrong. Nothing like trying to drive home in the dark with no headlights.

Good luck figuring it out.

 

[ToddG]

Its an electrical octopus!! My buddy's Benz had a similar problem. Every time he would use the power window switches, the horn would honk. Go figure.