HID lights keep turning off?

REDSKULL322

MEMBER
2012 FORD MUSTANG
3.7L
V6
2WD
AUTOMATIC
110,000 MILES

My car listed above (Premium) has HID lightbulbs (which I have never worked with before). With increasing frequency, I'm noticing that as I drive, both headlights (sometimes just one, sometimes the other, sometimes both) will turn off, and if I flip the light switch on and off, the headlights will come back on.

Again, since I'm unfamiliar with HID, I don't know whether this means that the bulbs have gone bad and need replacement, or if it's something more serious. Furthermore, I'm not sure if this is something that I can do myself or whether it would be best to take it in.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

This type of issue doesn't seem like the bulbs need to be replaced. Does this happen regardless of if it is on high or low beam? I ask because the high beam uses a relay which may be failing. On the other hand, if it happens with both, it could be a printed circuit board within the smart junction box under the dash. (See pic 1 below)

There are other things that can cause it, but based on what you describe, I suspect it is one of the two things I mentioned.

Let me know.

Joe

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Monday, January 9th, 2023 AT 5:55 PM

REDSKULL322

MEMBER
6 POSTS

It definitely happens when the car is using low-beams, but it is difficult for me to determine whether it happens with high-beams as well (I live in a major city and rarely have the opportunity to use them).

Is there a separate relay for the low beams that might be failing? Alternatively, if the issue is the circuit board you mentioned, what is the solution to fix this?

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Tuesday, January 10th, 2023 AT 3:25 PM

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

There isn't a relay for the low beam. That is controlled by the circuit board in the smart junction box (SJB). The high beam has a relay that is used to power a solenoid in the light assembly and provide high beam.

If the circuit board is faulty, and it sounds like it may be, the SJB likely will need to be replaced. However, I would first check to make sure there are no loose wires.

Try this. The SJB is on the right side (passenger side) either behind or above the kick panel. Turn the lights on and gently move around the wires going to it to see if the lights flicker. If they do, we likely have a connection issue. If there is no change, the SJB is the primary suspect.

Let me know what you find or if there is anything I can do to help.

Joe

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Tuesday, January 10th, 2023 AT 6:35 PM