LMM: ABS and Brake light on WOT

[buildingup]

Had this happen a couple times to me but when I get on the truck hard and stay in it the ABS light and brake light come on and I hear the chime for the next 30 seconds. No codes come on to read either which is weird. Truck is tuned for the 37s I am running and can't figure out why this is happening. Anyone have any input?

 

[Dirtymaxx03]

iirc once the tires are calibrated over 34.5 inches it causes a mis communication between the transmission and the ecm.

 

[buildingup]

But this should happen all the time when driving not just WOT. Normal driving everything is fine.

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[Dirtymaxx03]

so the lights will go off and always stay off unless you go WOT? then as soon as you floor it the lights come on?

 

[buildingup]

Yup lights are never on then if I go WOT they turn on and you hear the chimes. Once I turn off the truck no more lights as long as I drive like a normal person, once it's WOT everything lights back up.

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[Olecountry09]

Mine does the same thing. Any update on yours. Been unable to find my problem.

 

[THEFERMANATOR]

Mine does the same thing. Any update on yours. Been unable to find my problem.

I'm betting your speedo needs to be adjusted to a slightly shorter tire.

 

[Olecountry09]

Speedo is perfect with gps. At this point I will try anything. I will try dropping tire size a little. Thanks

 

[THEFERMANATOR]

Speedo is perfect with gps. At this point I will try anything. I will try dropping tire size a little. Thanks

There is a known problem with the abs in GM trucks where if you calibrate the speedo for a tire larger than 34.5 inches tall, it throws the abs off. Your speedo will be dead on, but the abs is still calibrated for stock tires, so the reading from the front speed sensors will vary too much from the speedo reading, and turn the light on.