BCM reprogramming options for tow/haul

holstbnet · January 5, 2006

Hello!

I have a 2003 Chevy S-10 LS 4.3 auto 2wd and have been making some modifications here and there. For example, I added factory foglights and the switch, harnesses etc. I tested functionality with the Tech 2, commanding the lights on and they work fine. However the BCM needs to be reflashed to support the foglights... I have to bring it to the dealer soon. They tell me it can be done no problem.

I am swapping in a center console from a SUV that includes a "tow/haul" switch on the shifter. And I know for a fact that Blazers/Jimmys and other S series utilitys were available with tow/haul mode, and I have a light on my gauge cluster for it. You cannot get tow/haul on a S-10 pickup though, and never could. I added a wire to the C3? BCM connector on the correct pin for tow/haul switch, and grounded it out but it did not turn the light on the cluster as to be expected.

BUT.. what I'm wondering is: while the dealer is reflashing BCM to support my new foglights, can they also add the tow/haul functionality? Are there strict calibration rules and it won't take a utilities BCM calibration in a pickup? Can you just pick and choose what options you want to enable?

I am just curious how that whole side works there...

GM-Tech · January 5, 2006

Sometims there are options that can be enabled in the BCM, such as fog lights, keyless entry, etc. There are no options for the PCM. User selectable options aren't available to the PCM because of strict government regulations concerning emissions. Any change would have to go through validation to ensure the vehicle meets the standards that applied to it when it was sold. When we program a PCM, the software we use presents a calibration and we can either accept it or not program the PCM. No options.

I don't see how tow/haul could be enabled on a vehicle that wasn't designed with it. The various modifications to the shift characteristics has to be available within the software to begin with. Just adding a wire ain't gonna do anything and even if it was something that could be turned on in the BCM, the BCM only gets the signal from the switch and then sends that request to the PCM, which doesn't have that feature on your vehicle.