Well after trying to find diagrams and failing I started comparing the post from the Silverado forum I mentioned earlier and the BCM in my car looked almost identical to the pics that were in that post. I followed the steps that were there and found the right pins and tested them with a test light to be sure and they were right. Pushed my diode in place and got exactly what I wanted. Full function of my fog lights plus they stay on with my high beams. Not sure how much it will actually help but fun to tinker with anyway. I find it very interesting that the pin location in the same plug in the BCM matches exactly from a Malibu to a Silverado but I guess why not..... Here is the post I followed.... Obviously the pics may vary a little as it is a pickup and we're talking cars.
2014 SIERRA SLT FOG LIGHTS WITH HIGH BEAM HEADLIGHTS MODIFICATION
This mod will let you use the fog lights on low beam same as factory. On and off with the fog light button.
When the fog lights are turned on while on low beam, then the high beams are either flashed or turned on and then off, the fog lights remain on when going back to low beam.
When the high beams headlights are switched on, the fog lights come on also. You cannot shut the fog lights off with the high beams on. When going back to low beam, the fog lights go off if they were off prior to switching high beams on.
Find the BCM under the dash, just to the left side of the steering column, right behind and above the OBD2 connector. It's a black box about 7" square and an inch thick. It will have 7 connectors in the lower edge of various colors.
Pull the BROWN connector loose. There is a little tab you need to squeeze inward to release it.
Look at it closely, there are tiny numbers at the corners to give you pin location reference. Use my attached connector photo and the numbers on the connector, along with the colors of the wires to locate the proper wires.
Locate pin #10 with the Brown and White striped wire. This is the Fog light signal wire for the relay.
Locate pin #18 with the Brown and Violet striped wire. This is the High Beam signal wire for its relay.
Take a 1N4004 diode and push the wire lead of the diode in along side the wires with a pair of needle nose pliers. You need to push hard to get it to slide in about 1/4" so it will stay snug. Make sure the marked end of the diode (stripe) is toward the High Beam.
You can put a piece of electrical tape over the bare diode leads or you can slip a piece of heat shrink over the diode before you install it and shrink it after pushing it in. But there's really no need as these are switched Ground leads, not power.
Put the BROWN connector back in the BCM.
YOU'RE DONE. THAT'S IT.
The BCM is behind this area (pic 1)
This is the BCM. (pic 2)
In this picture, my arrows point to the rows to intersect the proper wires. (pic 3)
The diagram below shows the connector oriented as you see it in the photo above so you can locate the correct pins. (pic 4)
Rectifier Diodes are available at any electronics store or Radio Shack.
Source: https://www.chevymalibuforum.com/threads/bcm-diagram.95322/
Posted by: juliannebirdettee08575.blogspot.com
