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New tires, ABS & Brake light, power loss

1311 Views 6 Replies 3 Participants Last post by  Grantman31
I have 99 1500 4/x4 with 318 engine, 5 speed manual tranny, and 3.55 diff. I recently installed some 255-85R16 tires. After about 50 miles my ABS and Brake lights came on, then 30 miles later I noticed a big loss of power going up hills, plus the engine started stalling every time I come to a stop. I expected some loss of power but not this bad.
Is this all related to the installation of the slightly larger tires? I've seen some of the previous posts on the ABS/Brake lights....but would that also be causing my power loss and stalling as well?
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With the ABS light, I am thinking speed sensor on the top of your rear diff. Those tires should not degrade your power like that.
I'd go by Autozone or your local parts store and have them check for any thrown codes.
The ABS/Brake light is usually the speed sensor.
Changing tires shouldn't cause the stalling/etc you mention.

KP guys were right on.
It was the speed sensor.
However, prior to installing it I was able to get a mechanic to flash the computer with the new tire size, so I am not sure if the speed sensor was itself responsible for the stalling....or if it was the computer compensating for less revolutions per mile.
BTW...initially I thought I would be able to simply disconnect the speed sensor and the computer might just cease trying to compensate for the "less revolutions"...but that just resulted in turning on the "check engine" light.
Glad it worked for you. When you say you got him to "flash your pcm", I hope you mean he just corrected the speedo for the tire size, and didn't do a software update! We like to call that the "death flash" and it will seriously hinder your performance. Let us know!
Nope....he simply corrected the speedo for tire size. The hand-held computer listed 3 or 4 options for Wrangler tires, but they were not the correct sizes. So he selected "other"....and I calculated the number of revolutions per mile for the 255-85R16's and he plugged that in.
I was simply amazed by all of the items that the computer could troubleshoot on the truck....he could even check individual injectors and spark plug wire resistance....amazing.
How much did that speedo correct cost you? I need to get mine done.
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