toolshell

New Member here. Been lurking around a little while but just joined. Great info on this site.
I recently purchased a 2006 F150 XLT Super Crew. I'm very excited to have a Ford product again. I had a '96 Ranger 4x4 that I loved to death and sold with 230,000 miles.
I have an issue with my F150. I apologize in advance this might end up being a novel. After purchasing the F150, my family and I took a 1500 mile+ road trip. On this trip I noticed that I seemed to be going a lot slower than those around me, although according to my speedometer a lot of the time I was speeding . I grabbed my GPS and checked the speedometer. Sure enough the speedo was 10-12 mph fast. I stopped in at a dealership along the way and had them look into the issue. They reprogrammed the tire size to the size on the truck (275/70R18) but the speedo was still off. They sent me on my way free of charge and suggested that it might be the speedometer itself. Once home I took it to the local dealership and passed on the info from the dealer on the road. Here's their writeup:

"Verified customer concern, no codes in system, started with output shaft speed sensor, did not correct concern. Found PCM reading speed indicated and all wheel speed sensors reading actual speed. PCM keeps returning PCM programming to a 265/45-22 Wheel/Tire size, considerably smaller than actual size. Believed to be PCM not adjusting for tire size and misreading vehicle speed possibly because of programmer messing up PCM"

They wanted 1000 bucks to replace the whole PCM and I said no. What you see above took them a week to accomplish. In the meantime I have a scangauge II with the digital speedometer corrected 9% working ok. So here's my question: What can I do to try to correct this issue short of putting in a new PCM? I thought about using an aftermarket programmer to attempt to reprogram the PCM (I found an edge evolution for a good price locally).
Any help would be appreciated.
Here's a picture of the truck:

madeSICC

Yea I would go the programmer route.

techrep

iTrader: (1)

Buy a used Edge it will fix it right up...just like the first tech said it messed it up...

Steved13

Hmm...I would think if the Ford dealer couldn't get the programming to stick, an aftermarket programmer wouldn't work either?

Swegner99

Did any of the dealers try to reflash your PCM? You can put a PCM back to factory original specs and its not hard to do, Ford has your "AS-BUILT" data stored and its can be forced back into the PCM. Sounds like the original owner had big wheels and tires and the speedometer was reprogrammed with a programmer. Took the wheels and tires off the truck and pulled the programmer out without resetting back to stock.

toolshell

No, neither one offered to re-flash. The local dealer just wanted to completely replace the PCM. I called the other dealership for a second opinion and they told me that they would only replace the PCM as a last resort, they were still sure it was the speedometer itself. I wasn't impressed. The local dealer kept the truck for over a week and just wanted to throw parts at it (a gambling habit financed with my pocketbook).
If I take it into another dealer and ask for a "re-flash" is it something they they would readily do, or do they need to run their diagnostic to see if they can justify it?

Steved13

Doesn't this mean they tried re-flashing?

toolshell

Is there a difference between a total reflash and just a tire size reprogramming?

Steved13

I'm not sure with the dealer program. With my SCT it's part of the flash programming.