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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15900
Experience:  15 years GM master tech
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Chevrolet Express 3500 LS: Having trouble finding +12v signal

Customer Question

Having trouble finding +12v signal at brake switch to install a brake controller
Submitted: 1 year ago.
Category: Chevy
Expert:  Gary replied 1 year ago.
how many wires are what colors are at the brake light switch connector ?it should look like this with these 4 wire colorsdoes the purple or the blue/white show 12 volts when you step on the brake pedal ?
Customer: replied 1 year ago.
There are four wires, none of them have voltage present???
Customer: replied 1 year ago.
But when I plug in the connector, and turn on the key, the brake lights work???
Customer: replied 1 year ago.
Is there something different about the 2011 Express? I have installed brake controllers on my previous vehicles, but they were all chevy or ford trucks.
Expert:  Gary replied 1 year ago.
one of those wires has to show 12 voltsfor the brake lights to work2011 chevy express that plug i showed you are the wire colors the same as your van ?
Expert:  Gary replied 1 year ago.
how many wires are in your connector ? 6 or 4 ?this might be a late 2011 and actually have 2012 wiring in it
Customer: replied 1 year ago.
I have a trusted and tested voltage meter, there is no voltage present at the plug. Someone told me that there is some kind of relay somewhere that this van uses to turn on lights, is that right?
Expert:  Gary replied 1 year ago.
if you have 6 then you are correct there will be no 12 volts at the brake switchthe BCM controls all the brake and lightingyou need to get to the BCM # ***** in the first picture and locate connector X5 as seen in the second picture and locate terminal # ***** a light blue/white wire in that connector and that wire should show 12 when stepping on the braketap into that wire for the brake signal for the trailer brake control