Reprogramming Speedo for Larger Wheels?

[mdadgar]

I thought I'd seen on the forums here that it was NOT possible for the dealer to reprogram the speedo electronics for larger wheels (but reprogramming the ABS *is* possible, but I can't see why it'd be required).

This morning my dealer not only claimed it was possible, but offered to do it free of charge when I needed it.

Once I recovered, I started thinking about whether it is even possible.

Anyone know for sure?

Thanks.

- Mark
'02 Sierra 2500HD SLT CC 4x4 SB D/A

[MudNurI]

A dealership in Keene, NH , Fairfields GMC has a 2002 2500 HD CC SB that they just put a 4" lift in, with 35's...John knows the owner-whose truck this is, and asked him this specific question...

his reply was that his speedo is correct, the service guys at that dealership reprogrammed it, and also fixed the ali to shift correctly....he had one of the cops that comes to the dealership clock him at 35, 50 and 65 to make sure it was right, and it is

hope this helps?
Brandy

[Wally]

Interesting. Both dealers in my area claim that they do not have the downloads needed to reprogram anything other than the ABS menu. They were instructed by GM to measure the rolling distance of the tires and report back. GM then took this number and attempted to match it to a tire size if they could not correct it within one percent they wouldn't issue a download. This was all before the infamous,"do not evaluate performance issues until the customer returns the tires to the stock size" bulletin came out. In lighht of this I would imagine that they will be even more hesitant to reprogram.

[Piney]

Mark,

My dealer told me that it was possible for them to reprogram up to 265s, but no larger. They also wanted a little over $100 to do it. (What a rip off) Anyway, in case you didn't know, performance products has a Jet 2000 speed control unit (part #5634) for $159.00. It supposedly recalibrates your speedo for larger tires, eliminates the top speed limiter, and adjusts the transmission shift points for larger tires. I know there are some that have purchased this and I haven't heard any negative comments about it. I want to go to 285s in the future and I'll probably try it then. Just FYI....

[TO-DMAX]

Took mine in to the local GMC dealer and offered to pay to have it recalibrated. The guy writing up the job said "no problem", but when the svc. mgr. walked by, he said "NO" and promptly provided me with a copy of that bulletin.

I'm gonna try my local Chevy dealer next. They might be more friendly.

[MaxRock]

When I put the 255-85x16s on, the Dealer offered to reprogram the speedo. Hooked up the TechII and off reprograming he went. In just a few minutes he stated it was completed. I went home and had the boss lady confirm the speedo with her Tahoe. Nothing changed, still 10% off. I believe the Dealer updated the computer for the anti-lock brakes, but is not able to update the speedo. I also had it checked at various highway construction zones that had the radar trailer out. Each time (4 different locations) my truck seems to be right at 10%. On the positive side, I'll get a 110,000 mile warranty!!! Oh well at least doing the math for the conversion is easy.

MaxRock

['burner]

Do any of you know what a "Variable speed sensor buffer" is? I noticed that Piney brought up the Jet 2000 speed control unit; would it be the same type. I am looking for a way to reprogram my '95 GMC 2500. My mileage and speedo are off 10%. The local gmc dealership mentioned something about the 'drack'cluster as if it was forbidded to mention. Is this something that is 'black box' material.

[MudNurI]

I do know that at our regular dealership- they would NOT recalibrate over a 265 tire...however I also know that it CAN be done, because of the truck with the lift...I think it has to do with the dealership- and who you know..I'm sure that Chris the owner of the dealership can "okay" recalibrating his own truck, however they would be more leary of recalibrating a customer's truck because of what The General says about it. It could cause some problems down the road if they do something againts policy and it comes back to bite them in the a**.....just my .02 though

Brandy

[SalmonExpress]

'burner, I replaced the 'Drack Module' in my 93 Suburban when I put 285's on it years ago. There is a place in Addison, IL that will recalabrate them. If you would like the name and phone number, give me an email at SalmonExpress@AOL.com as I am at work now and do not have that info with me.

Scott

[Rueben]

I just put the new fabtech 8" kit on my 02' Chev CC LS 4X4 D/A Pewter with 37X12.5-16 SuperSwamper SSR's, didn't do anything to anything and it still has a ton of juice. It almost seems to take off faster and have a more useable trans. For instance, first gear is much taller and I can use it for more acceleration and when my speedo reads 70mph (which is really 84mph) It will shift to 4th and pull most vehicles comperably equipted. I do wish I could find out all the facts about this truck instead of all this heresay I get at the dealer. Oh yeah, I put the K&N filter on part# 33-2135 and I can feel a small but noticable difference, worth the $57.79 delivered from 4filters.com. The turbo is a little louder and the power is a little better.