Passenger side HID does not get power

[Mike18GT350]

Hello,

I have a 2018 Shelby GT350. The car comes with HID headlights. I was on a drive in the fall and the passenger side HID went out. Only the HID went out, the three marker lights work fine. Before I hent ahead and replace the HID bulbs, I performed the following troubleshooting:

1. Checked the fuses (the 7.5 a in the passenger side kick panel and the 20 a fuse in the main box in the engine bay)
2. Pulled the front bumper and did a headlight flip. When plugged into the driver side, the passenger unit works fine. Additionally, when plugged into the passenger side, the drivers unit HID does not light.

My conclusion is that there is an electrical fault somewhere between the power source and the leads going into the headlight unit plug. Has anyone ever run into this issue before? Any help would be greatly appreciated.

Thanks,

Mike Santangelo

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[honeybadger]

Hey Mike - this might be helpful for how the headlight works. If I were to guess, your bulb on the passenger side is out.


Overview of s550 mustang headlight wiring

 

[Mike18GT350]

Thank you for this. The Passenger side unit works fine when plugged into the driver side. The issue is with the power getting to the plug wires for the HID.

Thanks,

Mike

 

[honeybadger]

Oh yeah, sorry. Completely miffed that one. Check the voltage at the plug according to the wires in the video and see if you have a short

 

[Mike18GT350]

Yup, those line are not sending power. I am now checking the headlight switch

 

[honeybadger]

Yup, those line are not sending power. I am now checking the headlight switch

the switch controls a relay. If you're not getting power at the plug, it's going to be a short between the fuse box and the plug, IMHO

 

[Mike18GT350]

Thanks

 

[kgschrader]

the switch controls a relay. If you're not getting power at the plug, it's going to be a short between the fuse box and the plug, IMHO

Not trying to be an a*hole, but if no power is there, it is mostly likely an open circuit.
If it is/was a short, the fuse would most likely be blown.


Kirby

 

[honeybadger]

Not trying to be an a*hole, but if no power is there, it is mostly likely an open circuit.
If it is/was a short, the fuse would most likely be blown.


Kirby

Doh! Clearly i'm not a sparky in my day job

you'd think after wiring a car, i'd remember the difference between open circuit and a short. then again, I still frequently burn myself on hot materials when fabricating, so not all that surprising.

 

[Adam the Lighting Guy]

Stupid question time.

Was the ground also checked for continuity?

One would think that a common relay would power the ballasts but with these Canbus cars it may be powered by the BCM or another module.

 

[JAJ]

Here's the wiring diagram for a 2016 GT350. Presumably the 2018 is similar.

HID power is fed directly from the Battery Junction Box through a 20A fuse to pin 10. Pin 1 is a signal that turns on low beam and pin 12 switches on high beam.

Pin 3 is power that runs the parking and marker lights that are controlled by a signal on Pin 5.

Presumably the two grounds are separate inside the unit - one for parking lights and one for the headlight.

Both right and left headlight connectors are pinned the same, so swapping the headlight demonstrates that the unit itself is working.

If you've got a voltmeter, check that there's power on pin 10 and check that pins 12 and 1 have high beam and low beam "on" signals on them. Then check that both pins 8 and 14 are grounded.

 

[Mike18GT350]

Here's the wiring diagram for a 2016 GT350. Presumably the 2018 is similar.

HID power is fed directly from the Battery Junction Box through a 20A fuse to pin 10. Pin 1 is a signal that turns on low beam and pin 12 switches on high beam.

Pin 3 is power that runs the parking and marker lights that are controlled by a signal on Pin 5.

Presumably the two grounds are separate inside the unit - one for parking lights and one for the headlight.

Both right and left headlight connectors are pinned the same, so swapping the headlight demonstrates that the unit itself is working.

If you've got a voltmeter, check that there's power on pin 10 and check that pins 12 and 1 have high beam and low beam "on" signals on them. Then check that both pins 8 and 14 are grounded.

Thank you! This is very helpful

 

[Mike18GT350]

Stupid question time.

Was the ground also checked for continuity?

One would think that a common relay would power the ballasts but with these Canbus cars it may be powered by the BCM or another module.

I have verified the ground

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