The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Check PCM Tire Size

**MidLifer** · 11-01-2017, 08:50 PM

I bought the PCM and harness from board member 68 Four on the Floor. He removed VATS and downstream O2 but did not say that he did anything else, so I'm assuming the PCM is programmed as it was when it was on the 2003 2500HD it came from. I don't see why he would have removed the torque management but I'm in touch with him over PM and will specifically ask.

I had read on another forum that if the tire size or rear ratio is markedly different from the vehicle it came out of it can mess with the shift points. I'm assuming that my tires (235/75R16) are not that different from what was on there but I have a 4.10 rear and the truck may have had 3.42 or something different.

In any case, do I need tuner software to check this or can I read it through an OBDII reader with an app?

11-01-2017, 08:50 PM	#3
MidLifer Senior Member Join Date: Apr 2011 Location: South NJ Posts: 1,269	Re: Check PCM Tire Size - Rear Ratio I bought the PCM and harness from board member 68 Four on the Floor. He removed VATS and downstream O2 but did not say that he did anything else, so I'm assuming the PCM is programmed as it was when it was on the 2003 2500HD it came from. I don't see why he would have removed the torque management but I'm in touch with him over PM and will specifically ask. I had read on another forum that if the tire size or rear ratio is markedly different from the vehicle it came out of it can mess with the shift points. I'm assuming that my tires (235/75R16) are not that different from what was on there but I have a 4.10 rear and the truck may have had 3.42 or something different. In any case, do I need tuner software to check this or can I read it through an OBDII reader with an app?