Hello group!

Having an issue but let me add what lead us here -

2012 GMC Terrain, driver side headlight is/was out.

Purchased some new bulbs in order to replace them, and it'* still out. Swap bulbs from driver to passenger, and the driver side is still out. The original bulb I pulled was good as well.

Next step was to check the fuses. First with those under the hood as well as relays. I really only played with the high-beam since I saw no fuse for low beam.

To add, the high-beams DO work on both sides. The headlight passenger side does work when headlights are manually turned on, and DRL on both sides work.

I read on another forum where a bad BCM module fuse can attribute to a headlight issue so I shut the vehicle off (with battery still in place) and pulled the BCM module 1, and 2 (I believe in spots #4 and # as well as I think another BCM module fuse. All fuses tested in working condition.

I replace the fuses, ensuring they are fully seated, then proceed to start the car. This is when I was presented with lights on my dashboard and being prompted to SERVICE POWER STEERING, SERVICE ABS, etc.

Vehicle'* functions do not work, whether it'* the power windows, power locks, and the vehicle will not shift out of park. The lights, highbeams, nothing I do works outside of the stereo and climate control.

This tells me it has to be one of the modules has "reset" due to my removal of fuses.

I read on another thread to disconnect the battery for +15minutes, reseat/replace the BCM module fuses, and touch the positive/negative battery cables (after the battery has long been disconnected) to discharge the vehicle fully. This was all just done.

Connected everything back up, fired up the vehicle, and was presented with all the same messages and symptoms. Even the parking brake shows engaged but it is not.

To add, the vehicle drove perfectly fine as it'* a daily driver all before I ever removed any fuses. And the battery is only 2-3 months old as it was replaced under warranty. It measures at +13.1v so I know it'* fine, it starts up right away.

I did the whole "leave the key in the ignition, on position, vehicle off, for 11 minutes) and none of this helped.

The only light that remains when I turn the vehicle off is the battery symbol and the battery key could not be removed so I had to use the tiny little hold to allow to turn the key fully in order to remove.

What process am I missing or what am I doing wrong?

Tried to be as thorough as possible.

I meant to say *the key could not be removed* but I am not allowed to edit my posts.

You are allowed to edit, as long as you save it before five minutes elapses after the original post time and date. Back in the day, this was done to prevent people from changing what they said after stirring up days of drama. I took care of it for you.

It doesn't have fuses or relays in either fuse/relay panel for low beams. Check out this diagram, here'* where to start:


From: https://charm.li/GMC%20Truck/2012/Te...%20Schematics/

I'm guessing there is no power going across one of the BCM module fuses you tested, one or more of them isn't making good contact, or one or more of the fuse terminals is damaged or defective. Get a volt meter and see how many volts are making it across.

For the headlight issue, I'd check on the ground for the left headlight before doing anything else.