VSC and ABS lights turn when Headlights Switch On

[Hazel]

My VSC and ABS lights turn on when my headlights switch on. They will stay on until I restart my engine.

I'm not sure exactly when this issue started as it only happened very rarely and I originally assumed it was a wheel speed sensor.

One of the first mods I did to my car was aftermarket headlights and taillights, and I've read around that sometimes those changes can cause this to happen. However, as time has gone on it has become more common and now after I replaced the LEDs in the gauge cluster the warning lights almost always turn on whenever the headlights or marker lights are switched on.

If anyone has any ideas of what might cause or where to start to diagnose this, it would be appreciated.


Edit: After replacing the aftermarket 4th taillight the previous owner installed, the problem has gone away entirely.

[Ultramaroon]

Reinstall your stock lights first.

[Hazel]

Originally Posted by Ultramaroon

Reinstall your stock lights first.

Unfortunately it's been well over a year since I've been in possession of the stock lights. This issue didn't start coming up until long after I installed them.

[Ultramaroon]

Originally Posted by Hazel

Unfortunately it's been well over a year since I've been in possession of the stock lights. This issue didn't start coming up until long after I installed them.

[soapbox]Remember this lesson when considering future mods. I have all of my stock stuff.[/soapbox]

Disconnect one bulb and test drive until the MIL is thrown. Leaving it disconnected, disconnect another and repeat testing until the MIL is no longer thrown.
Then, leaving that last bulb disconnected, reconnect all the others. Does the MIL get thrown again, or did you find the bad/noisy unit?


edit: Okay,,, not MIL, bur rather that odd combination of lights. Is that limp mode?

[Hazel]

Originally Posted by Ultramaroon

edit: Okay,,, not MIL, bur rather that odd combination of lights. Is that limp mode?

It's not limp mode, in fact it seems like the ABS is still functional while the lights are on. The only thing it seems to effect is that I can't use cruise control.

However, after a series of pulling fuses and disconnecting things, I have narrowed it down to the 4th brake light being the issue. The previous owner of my car installed an aftermarket one and completely disconnecting it seems to solve the problem.

Might be something related to the fact that the wiring for it is tapped into the taillight and wires to provide taillight functionality, unlike the stock one.

I ordered a different one and I will see if I have any luck with that one.

[Teseo]

Originally Posted by Hazel

It's not limp mode, in fact it seems like the ABS is still functional while the lights are on. The only thing it seems to effect is that I can't use cruise control.

However, after a series of pulling fuses and disconnecting things, I have narrowed it down to the 4th brake light being the issue. The previous owner of my car installed an aftermarket one and completely disconnecting it seems to solve the problem.

Might be something related to the fact that the wiring for it is tapped into the taillight and wires to provide taillight functionality, unlike the stock one.

I ordered a different one and I will see if I have any luck with that one.

Report any update, pls

[Hazel]

After replacing the aftermarket 4th taillight the previous owner installed, the problem has gone away entirely