ABS and Brake light on, plus valve chatter

[Andy H]

I have a 2008 silverado 5.3 with LY5 motor. I ran the 87 octane tune and disabled DOD and changed tire size to 35". Also changed tcm for firm shifts. When going up hills, the valves chatter. So, I went with the mpg booster tune and disabled DOD, tires size 35" and firm shifts. After about 5 minutes of highway driving, the ABS and Brake lights came on. My main reason for buying the tuner was to change my tires size. I just had my truck lifted 6" and put on 35/12.50/20 tires. Any ideas?

Also was wondering if I want to change tunes like going from 87 octane to mpg booster, do I have to go to stock first then change? Basically I'm wondering if I will lose my original backup.

Thanks,
Andy

[garrett]

have you tried measuring the tire from the ground to the top of the tread ? Does the tire measure out to 35'' exactly?

[Andy H]

No, but I'll do that when I get home this evening. They are 35/12.50/20 nitto terra grappler g2

[Andy H]

at around 38psi, from the ground to the top of the tire is 34"

[Andy H]

Tonight, I restored my stock tune. Then, I updated the intune. Next, I just modified my stock ecm tune and the only thing I changed is I disabled DOD and changed the tire size this time to 34.5". I will drive it in the morning and see if it still throws the abs light. Now, in the future, if I want to run the 87 octane tune, what can I do to get the valves to quit pinging when under load?

[Andy H]

Abs light still comes on. Also, my Speedo on the truck said 55 and my GPS said 52. What else can I try?

[06MonteSS]

2007 and 2008 trucks have a limit in the ABS controller for how big you can go with tire size.. and your tires/size is too big.. you need to set the tire size smaller to get the ABS codes/light to go off.. go smaller a half inch at a time until the light goes out...

[Andy H]

Ok, does this tune write to the abs module? I talked to a shop around town and they said the tech 2 can change tire size in the abs module. Should I have them try that as well?

[06MonteSS]

no.. the programmer can't do anything about the abs module...

if dealer can reprogram the abs module to allow bigger size and not cause it to trip, then sure, have them do it...

[Andy H]

No go on programming the abs module. They hooked up the tech2 but it didn't give them any options for tire size for my 2008 truck. I am down to 33.5" tire size setting with the diablo. Instead of tripping the abs light around 45 to 50 mph like before, now you have to be going faster like say 55 to 60 before it trips. So is there anything I can do? Dealership said they couldn't do anything. I hate that I paid so much money for the diablo and can't use it.