Truspeed question
Fulltime INFIDEL!
Joined: Jul 2010
Posts: 252
Likes: 0
From: Down South
I called SCT and asked them. They said in theory that shouldn't happen because their product doesn't touch the module that calibrates the speedo. However, using that logic I shouldn't have to go to stock to use the Hypertech. I called Innovative, and they basically said the same thing. In the end, it wasn't worth the risk of locking up my truck's ECU. The Truespeed does look like a pain, but it may be the only option. I returned the Hypertech.
Posting Guru
Joined: Oct 2009
Posts: 2,453
Likes: 4
From: AZ
From SCT
Tire Size
Allows you to set the tire size to correct shift patterns and the speedometer on your vehicle.
<LI class=Options>
From A/E
Tire Size Programming up to 40" ('99-'03 7.3L, and '04-'07 6.0L)
this is the best find someone with an A/E to do it for free
Trending Topics
Hotshot
Joined: Dec 2003
Posts: 15,368
Likes: 121
From: Stuttgart, Ar
Maybe on the newest SCT's it's a function, but none that I've ever seen. Definitely not on the Xcal2 or 3 and not the older livewire's.
After searching the SCT site all I can find is 6.4 speedo correction. Can you provide a link??
After searching the SCT site all I can find is 6.4 speedo correction. Can you provide a link??
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
The module you're programming when you set tire size is the ABS module. So I don't see how it could effect the PCM programming. At least that's how it works with AE. You go to the ABS module and set the tire size. Up to 40" if I recall.
I'm somewhat curious about the effect devices like the Truspeed will have on the ABS functionality. The ABS monitors the speed of both front wheels individually, and the rear wheels together by measuring the speed of differential ring gear.
The Truspeed, and other devices like it, modify the rear ABS sensor signal to make it appear that the wheels are turning a different speed than they actually are. So the ABS module will see a different speed from the front speed sensors and the rear one. What does the ABS module do with this conflicting information and how does it effect ABS operation? I've never heard anyone speak to this before.
I'm somewhat curious about the effect devices like the Truspeed will have on the ABS functionality. The ABS monitors the speed of both front wheels individually, and the rear wheels together by measuring the speed of differential ring gear.
The Truspeed, and other devices like it, modify the rear ABS sensor signal to make it appear that the wheels are turning a different speed than they actually are. So the ABS module will see a different speed from the front speed sensors and the rear one. What does the ABS module do with this conflicting information and how does it effect ABS operation? I've never heard anyone speak to this before.
Senior User
Joined: Apr 2004
Posts: 235
Likes: 1
From: Fayetteville, NC
I have the truspeed on my 03 f250. I got it long before i got the AE so its still on there. The truspeed basically wires in AFTER the abs module on the superdutys. Therefore the abs still reads wrong (as in it "sees" a different speed than the vehicle is acutally going), but will still operate correctly as far as wheel lock up goes during panic stopping, since ive gotten the abs to kick in a few times. The abs sends a "conditioned" speed signal out to all the other modules, airbag, pcm, dash, wipermotor (for speed calibrated intermittent wipe, believe it or not) and the radio for speed sensitive volume if you have the higher end radios. The truspeed hooks in to that wire from the abs to every other module. On my 03 its under the left battery in the wheel well, but i think they moved it after 05 and im not sure if the wire colors would match up.
One other thing about the truspeed I dont care for but doesnt cause any issues as far as I know is that at low speeds like idling in a parking lot or backing out of the drive way the speedo needle bounces from its actual reading up to 35-40mph or so and back until I hit 10mph then it smoothes out
One other thing about the truspeed I dont care for but doesnt cause any issues as far as I know is that at low speeds like idling in a parking lot or backing out of the drive way the speedo needle bounces from its actual reading up to 35-40mph or so and back until I hit 10mph then it smoothes out
