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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Working on a 2010 Chevy K2500 brake lights staying on with

Customer Question

Working on a 2010 Chevy K2500 brake lights staying on with key on
Submitted: 1 year ago.
Category: Chevy
Expert:  Mike S. replied 1 year ago.

Will the stop lamps go off if you disconnect the wiring at the stop lamp switch?

Customer: replied 1 year ago.
no
Expert:  Mike S. replied 1 year ago.

Odd indeed. Let me get a wiring diagram. BRB

Expert:  Mike S. replied 1 year ago.

I honestly have no idea on how to diagnose this. You might want to retrieve the codes from the bcm though.

Expert:  Mike S. replied 1 year ago.

I can give you the wiring diagrams since I had already looked them up.

If you have retrieved any codes or are going to I'll hang on, if not, I think I will have to opt out.

Customer: replied 1 year ago.
I have the diagrams from prodemand--I also did not have any codes-----all signals from brake switch and t/s switch have been removed at BCM connectors X1 and X3
Expert:  Reggie Whiddon replied 1 year ago.

HELLO YOU SAY YOUR BRAKE LIGHTS ARE STAYING ON

Expert:  Reggie Whiddon replied 1 year ago.

WHAT have you done as far as work, have you checked the switch

Expert:  Reggie Whiddon replied 1 year ago.

HAVE YOU REMOVED THE STOP LAMP RELAY,

Customer: replied 1 year ago.
I have replaced the switch-BCM and under hood fuse block as far as the relay I have yet to find a stop lamp relay
Customer: replied 1 year ago.
I have also removed all inputs for the brake switch and t/s switch from bcm at connectors x1 and x3
Expert:  Reggie Whiddon replied 1 year ago.

What about the junction block in the rear if u disconnect there do they go out? I had one that had shorted internally

Customer: replied 1 year ago.
I did disconnect the junction block and still have brake lights according to my Tech II scanner, I did notice yesterday that the lights come on as soon as the key is turned to the acc position, according to the schematic there is a acc input on x1 so I removed it from the connector but still have lights on
Expert:  Reggie Whiddon replied 1 year ago.

Wait a minute you said you had brake lights "according to my Tech II scanner" are the lights actualy on are we talking about an input your seeing in data?

Customer: replied 1 year ago.
The lights are on I just use the tech so I don't have to keep going to the back of the truck to check the status.
Expert:  Reggie Whiddon replied 1 year ago.

It is good you have a tech 2, if you do a total dtc check what codes do you have in what module

Expert:  Reggie Whiddon replied 1 year ago.

I am pulling up the wiring now we are fixing this today!!! You say lights are on with key in the acc position? And u have disconnected the bcm, switch and even the joint connextor at rear?

Expert:  Reggie Whiddon replied 1 year ago.

Okay the stop lamp relay I asked you about earlier, is integral to the underhood fuse box. Which you say you have replaced. You also stated you replaced the BCM, did you perform thr programming for the BCM? If it were not programmed with correct rpo, could cause issue.

And lastly with everything hooked up, if you started with switch, bcm, fuse box joint connector what can you unplug and make these lights go off? I would like to know that and the results of a total system dtc check of all modules.

Customer: replied 1 year ago.
The bcm was programmed by Vin and rpo. Full system dtc scan shows no codes. The only thing that turns out the lights is unplugging x1 or x3 at bcm.
Expert:  Reggie Whiddon replied 1 year ago.

Do you have a short to voltage in x3 pin 13

Customer: replied 1 year ago.
I will call tomorrow. What will be a good time
Expert:  GM Bob replied 1 year ago.

Hello my name is ***** ***** I can help.

Need a volt meter to test not a test light

Have you check for for voltage at the brake switch terminal C? Terminal D should read O volts when the pedal is pressed?

This is how the system work (When the driver presses the brake pedal, the switch contacts open and B+ is interrupted to the body control module)

Please get back with me

Thank you

Expert:  Reggie Whiddon replied 1 year ago.

Hello you can call anytime tomorrow, thank you

Expert:  GM Bob replied 1 year ago.

Just checking to see if you need any more help.