My left hand headlight is stuck on high beam

[COYOTE1952]

hi can anyone please tell me why my left hand headlight is stuck on high beam please , the right one works fine both high and low but the left one is stuck on high, i ve checked the globe and its ok as are the fuses and relays, i could nt find the headlight control module, but was told my Australia shipped mustang did nt have one, is that true? any help would be appreciated thank you

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[Skye]

I do not have an answer for you. But the problem did make me think of a feature.

Attached is an excerpt from the US manual. It describes Automatic High Beam Control.

If you have the option, see if you can unselect it. Curious if the condition changes.

The excerpt also lists reasons why problems might occur.

While it doesn't explain why one lamp is doing this, maybe it could help in diagnosing.

Edit,

It's a stretch, but I also wonder what effect disconnecting the battery would have. Disconnect, wait 30 minutes for everything to de-energize, then reconnect. It won't hurt. And while it might not fix the problem, it might give tells as to where the problem area might be.

 

[Nightmonkey]

A motor in the headlight that moves a flap.
The mechanics in the headlight, the motor or the current flow to the motor may be the problem if it only occurs on one side.

 

[Skye]

https://www.mustang6g.com/forums/threads/driver-side-headlight-stuck-on-high-beam.78216/

Pretty cool. @Fenix supplied a photo of the assembly for the bulb.

 

[Mach VII]

I am shocked that is how this functions, what happened to the 'digital age'?

 

[Nightmonkey]

That's how this works for decades for bi-xenon HID.
It is proven solid and good, no "digital shitification", because hidden for the customers eyes.
There a itterations of this, e.g. with a drum with different silhouettes for different patterns of light output, which is rotated to change the pattern.

If you want "digitalisation", you need to get a car with multi beam led head lights.

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