Speedo Calibration On Nnbs

[ursandal]

I have a NNBS 2500HD (6.0l). I took it to the dealer to have the computer flashed for new tires. Went from 245 to 265. Not a big difference but it was only going to cost $35 so I figured what the heck.

 

Anyway, they evidently have never done this to a NNBS. They said that they could only calibrate the ABS speed sensor but not the speedo. Has anyone else had this done to their NNBS truck? If so were you able to check your speedo against a GPS to see if it worked or not? They said they would try and figure it out with GM on Monday but I figured I'd try and educate myself a little here before they call me back.

 

On another note, I asked if they would re-calibrate the rear TPMS alarm down to 60psi, currently running at 80 psi, so I could soften the ride. They refused to touch them. Anybody had any experience with this? Is it even possible?

 

Thanks in advance for your help!!

 

Al

[Canuck2500hd]

I used a hand held programmer on my buddies NBS Silverado. Changed from stock to 38", worked perfect.

[ursandal]

I used a hand held programmer on my buddies NBS Silverado. Changed from stock to 38", worked perfect.

 

Yeah, they claimed it was different with the NNBS...

[SS Crew]

I had my 07 2500HD gasser in for the trans shifting irregular. If the truck is in 2nd gear and if I nail the gas, when it downshifts into 1st, it slips like crazy up to about 5000 rpm then it slams into gear. The first dealership downloaded an updated shifting program and said that that would take care of the problem - it only made it worse. Now the shifting is very erratic; it holds the low gears too long and shifts out of the upper gears too soon, but won't go into 6th until almost 60 mph.

 

I took it back to the dealer and they said that there were no codes, they dropped the trans pan and found no clutch material - so they said there was nothing with the trans - it was because my tires are non stock. That's BS if you ask me. My tires are 305-50-20's and 32.0" tall. The stock tires were 265-70-17's and those were 31.7" tall. A difference of 3/8" - the thickness of a tread block. They are telling me that the 3/8" is going to confuse the computer and cause my trans to slip.

 

They told me that GM can send them a program that will calibrate my the computer to my tires, but it costs $160. I said fine, but if the problem is still there, you guys will eat the $160. They said no it doesn't work that way. I told them to get the download from GM and install it so we can get the trans thing done. Well it turns out that GM offers the tire calibrations for the 1/2 ton trucks, but not the 3/4 or larger trucks - they say it's a liability issue.

 

I talked to the service manager and told him that the 3/8" in tire difference will not throw off the computer - I'm only rolling and extra 1-1/8" per tire revolution and if the computer is that sensitive, what happens when the tires wear out? - then their diameter is 3/4" smaller! I told him to throw on a set of take off rims and tires they've got laying around. He told me that he didn't have time to change out tires and who will pay for that? I told him that I'll change the tires myself - it's only 32 lug nuts, I'll have it done in 20 minutes. He refused to proceed. I told him that this is called customer service. He told me if I wanted customer service, I should go someplace else. I then went to the dealership general manager and told him my situation and he sided with the service manager. Wait until I get my dealership survey - Screw those guys! All zeros!

 

I called the GMC helpline and they told me that since I changed out my tires to a non-stock size, I have voided my warranty. WTF?

 

Do not take your vehicles or make any purchases from Reynolds Buick Pontiac GMC in West Covina, CA!

 

Right now my truck is at another dealership, they have found parts in the valvebody and a coupe of solenoids that were defective. The parts will be in Monday, so I'll let you know what happens.

 

But getting back to speedo calibration, don't go to the dealership for that - they'll screw you, get a custom tune that includes a tire recalibration. Your truck will run tremendously better. I've got a custom tune, but that wasn't the problem.

[ursandal]

I had my 07 2500HD gasser in for the trans shifting irregular. If the truck is in 2nd gear and if I nail the gas, when it downshifts into 1st, it slips like crazy up to about 5000 rpm then it slams into gear. The first dealership downloaded an updated shifting program and said that that would take care of the problem - it only made it worse. Now the shifting is very erratic; it holds the low gears too long and shifts out of the upper gears too soon, but won't go into 6th until almost 60 mph.

 

I took it back to the dealer and they said that there were no codes, they dropped the trans pan and found no clutch material - so they said there was nothing with the trans - it was because my tires are non stock. That's BS if you ask me. My tires are 305-50-20's and 32.0" tall. The stock tires were 265-70-17's and those were 31.7" tall. A difference of 3/8" - the thickness of a tread block. They are telling me that the 3/8" is going to confuse the computer and cause my trans to slip.

 

They told me that GM can send them a program that will calibrate my the computer to my tires, but it costs $160. I said fine, but if the problem is still there, you guys will eat the $160. They said no it doesn't work that way. I told them to get the download from GM and install it so we can get the trans thing done. Well it turns out that GM offers the tire calibrations for the 1/2 ton trucks, but not the 3/4 or larger trucks - they say it's a liability issue.

 

I talked to the service manager and told him that the 3/8" in tire difference will not throw off the computer - I'm only rolling and extra 1-1/8" per tire revolution and if the computer is that sensitive, what happens when the tires wear out? - then their diameter is 3/4" smaller! I told him to throw on a set of take off rims and tires they've got laying around. He told me that he didn't have time to change out tires and who will pay for that? I told him that I'll change the tires myself - it's only 32 lug nuts, I'll have it done in 20 minutes. He refused to proceed. I told him that this is called customer service. He told me if I wanted customer service, I should go someplace else. I then went to the dealership general manager and told him my situation and he sided with the service manager. Wait until I get my dealership survey - Screw those guys! All zeros!

 

I called the GMC helpline and they told me that since I changed out my tires to a non-stock size, I have voided my warranty. WTF?

 

Do not take your vehicles or make any purchases from Reynolds Buick Pontiac GMC in West Covina, CA!

 

Right now my truck is at another dealership, they have found parts in the valvebody and a coupe of solenoids that were defective. The parts will be in Monday, so I'll let you know what happens.

 

But getting back to speedo calibration, don't go to the dealership for that - they'll screw you, get a custom tune that includes a tire recalibration. Your truck will run tremendously better. I've got a custom tune, but that wasn't the problem.

 

 

Wow, what a nightmare!! I haven't notice any difference in shifting but I guess my 265's are still within the stock tire range (31.6"). Thanks for the info, I'm not interested in paying $160 for the small amount that my speedo is off, $35 was one thing but for $160 I might as well get a tune or a handheld. Good luck with your truck, give 'em hell!!

 

Al

[irengineer]

I had my 07 2500HD gasser in for the trans shifting irregular. If the truck is in 2nd gear and if I nail the gas, when it downshifts into 1st, it slips like crazy up to about 5000 rpm then it slams into gear. The first dealership downloaded an updated shifting program and said that that would take care of the problem - it only made it worse. Now the shifting is very erratic; it holds the low gears too long and shifts out of the upper gears too soon, but won't go into 6th until almost 60 mph.

 

I took it back to the dealer and they said that there were no codes, they dropped the trans pan and found no clutch material - so they said there was nothing with the trans - it was because my tires are non stock. That's BS if you ask me. My tires are 305-50-20's and 32.0" tall. The stock tires were 265-70-17's and those were 31.7" tall. A difference of 3/8" - the thickness of a tread block. They are telling me that the 3/8" is going to confuse the computer and cause my trans to slip.

 

They told me that GM can send them a program that will calibrate my the computer to my tires, but it costs $160. I said fine, but if the problem is still there, you guys will eat the $160. They said no it doesn't work that way. I told them to get the download from GM and install it so we can get the trans thing done. Well it turns out that GM offers the tire calibrations for the 1/2 ton trucks, but not the 3/4 or larger trucks - they say it's a liability issue.

 

I talked to the service manager and told him that the 3/8" in tire difference will not throw off the computer - I'm only rolling and extra 1-1/8" per tire revolution and if the computer is that sensitive, what happens when the tires wear out? - then their diameter is 3/4" smaller! I told him to throw on a set of take off rims and tires they've got laying around. He told me that he didn't have time to change out tires and who will pay for that? I told him that I'll change the tires myself - it's only 32 lug nuts, I'll have it done in 20 minutes. He refused to proceed. I told him that this is called customer service. He told me if I wanted customer service, I should go someplace else. I then went to the dealership general manager and told him my situation and he sided with the service manager. Wait until I get my dealership survey - Screw those guys! All zeros!

 

I called the GMC helpline and they told me that since I changed out my tires to a non-stock size, I have voided my warranty. WTF?

 

Do not take your vehicles or make any purchases from Reynolds Buick Pontiac GMC in West Covina, CA!

 

Right now my truck is at another dealership, they have found parts in the valvebody and a coupe of solenoids that were defective. The parts will be in Monday, so I'll let you know what happens.

 

But getting back to speedo calibration, don't go to the dealership for that - they'll screw you, get a custom tune that includes a tire recalibration. Your truck will run tremendously better. I've got a custom tune, but that wasn't the problem.

 

 

Wow, what a nightmare!! I haven't notice any difference in shifting but I guess my 265's are still within the stock tire range (31.6"). Thanks for the info, I'm not interested in paying $160 for the small amount that my speedo is off, $35 was one thing but for $160 I might as well get a tune or a handheld. Good luck with your truck, give 'em hell!!

 

Al

 

 

The 2-1 problem you described is not normal. When the current dealership has returned the vehicle let us know how that turns out. Hopefully the valve body and TEHCM swap will fix that.

 

The shift pattern change is working as designed. The shift points were changed to improve response by staying in each gear to a slightly higher speed (more gear ratio, more response). Like you mentioned, the minimum 5-6 is over 50 mph. The downshift points were lowered (lower throttle position) as well. These were all done in response to customers feedback.

 

I believe you should be able to get the original calibration reinstalled if you liked that one better (the latter one that was installed was available for service but it was optional with the original one). Keep in mind if the new dealership replaces the TEHCM (Computer and Solenoid Module) the transmission will go thru a short period of adapting for shift feel. Every shift adapts independently (1-2, 2-3, 3-4....6-5, 6-4, 6-3....3-1, 3-2, 2-1) and since the new TEHCM didn't go thru the final test process attached to your transmission at the trans assembly plant the dealership should run the service fast learn process to get the adapts as close as possible before they hand it back to you.

 

Good Luck.

[ursandal]

Well the dealer just called back after talking with GM about how to calibrate my speedo for 265 tires. GM told them that the 265's were not a "supported tire size" and that they couldn't do it. The dealer didn't understand this since you can get a 265 as an option on the truck, the only difference being it's a 17" wheel, mine are on 16". It obviously can be done but GM would not give the dealer some number that they would have to input into the computer in order for it to work.

 

Guess I'll just leave it the way it is.... Thanks for your help GM!!

 

Al

[SS Crew]

Well, I got my truck back. They found a code in the trans computer that led them to replace the gasket / plate between the valve body and the trans. They said that everything works fine. Well, guess what? It's doing the same thing. I'm heading to the river this weekend so it'll be going back in on Monday - Wish me luck.

[chrisb1]

Bullydog Speedometer Calibration Tool:

 

V 1.1.5 January 10, 2008

 

- Updated the speedometer tool so that it will work on late 06 -08 lbz and lmm GM diesels

 

[ursandal]

Bullydog Speedometer Calibration Tool:

 

V 1.1.5 January 10, 2008

 

- Updated the speedometer tool so that it will work on late 06 -08 lbz and lmm GM diesels

 

 

If I knew someone that had one maybe, but I'm not dropping $600+ for one myself. I'm good with the truck the way it is. It's just irritating that GM won't do it when we all know they can. Probably the darn lawyers getting involved or something..

[Mike2500HD]

Bullydog Speedometer Calibration Tool:

 

V 1.1.5 January 10, 2008

 

- Updated the speedometer tool so that it will work on late 06 -08 lbz and lmm GM diesels

 

 

If I knew someone that had one maybe, but I'm not dropping $600+ for one myself. I'm good with the truck the way it is. It's just irritating that GM won't do it when we all know they can. Probably the darn lawyers getting involved or something..

 

What a bunch of crap!! I only bought my truck last month and I've been driving a GMC since the mid 90's but I wish I read some of this stuff before I bought it. I already have an issue with the 245 75 E tires and the pressure sensor. 80 psi being way too much pressure for an empty 3/4 ton truck. I drive an 06 1 ton at work with 265 75 16 E tires, and it handles like a sports car. It rides a bit stiff but I like it better than the way my 3/4 ton rides. I blame it on the 245's being more flexible in the sidewall, and I was planning to dump the stock tires as soon as I can justify it...and now I hear that GM thinks its a liability issue for me to go to better tires? This all makes me worry about the on-star also. They know how fast your driving, what tire pressure your running, they know exactly what your doing and where. I know this sounds paranoid but in the event you have an accident I bet this information can be discovered by the insurance company lawyers to use against you. Theres no way Im renewing the onstar for the price but I dont even want the technology in my truck. They are out of controll if they are telling you a fraction of an inch of tire diameter is a liability issue! Or that its causing your transmission to slip! This is why Toyota is now the number one manufacturer. I really think we need to start to organize responses to this and threaten suit against them when there refusal to act results in an accident. What the hell? Between corporate weasels, lawyers, insurance company dweebs and polititions we dont have a chance....

[ursandal]

Bullydog Speedometer Calibration Tool:

 

V 1.1.5 January 10, 2008

 

- Updated the speedometer tool so that it will work on late 06 -08 lbz and lmm GM diesels

 

 

If I knew someone that had one maybe, but I'm not dropping $600+ for one myself. I'm good with the truck the way it is. It's just irritating that GM won't do it when we all know they can. Probably the darn lawyers getting involved or something..

 

What a bunch of crap!! I only bought my truck last month and I've been driving a GMC since the mid 90's but I wish I read some of this stuff before I bought it. I already have an issue with the 245 75 E tires and the pressure sensor. 80 psi being way too much pressure for an empty 3/4 ton truck. I drive an 06 1 ton at work with 265 75 16 E tires, and it handles like a sports car. It rides a bit stiff but I like it better than the way my 3/4 ton rides. I blame it on the 245's being more flexible in the sidewall, and I was planning to dump the stock tires as soon as I can justify it...and now I hear that GM thinks its a liability issue for me to go to better tires? This all makes me worry about the on-star also. They know how fast your driving, what tire pressure your running, they know exactly what your doing and where. I know this sounds paranoid but in the event you have an accident I bet this information can be discovered by the insurance company lawyers to use against you. Theres no way Im renewing the onstar for the price but I dont even want the technology in my truck. They are out of controll if they are telling you a fraction of an inch of tire diameter is a liability issue! Or that its causing your transmission to slip! This is why Toyota is now the number one manufacturer. I really think we need to start to organize responses to this and threaten suit against them when there refusal to act results in an accident. What the hell? Between corporate weasels, lawyers, insurance company dweebs and polititions we dont have a chance....

 

 

I hear ya man!! As far as them refusing to update my tire size I'm tempted to try another dealership just to see what they say about it. I have no reason to doubt the original dealership, I mean it was money lost to them.

 

The TPMS thing is a bummer though, and again maybe a different dealership would be able to recal the system, for lower pressures. I've got my rears down to 70psi now and it seems a little less harsh, that's with 265's too. I'll probably bring them down to 65psi and see what that does. Since mandated TPMS is new I think it will take a little while for the dealerships to loosen up a little and make adjustments. The question is can they change the tolerances?? If it is possible I'm sure the handheld programmer companies out there will figure it out and make it an option also.

 

Don't give up on your truck and do anything silly like a buy a Toyota! Despite these couple of annoyances I love my truck and wouldn't trade it for anything.

 

Al

[nbscanuck]

The TPMS is in BCM (Body Control Module) which is not accessible by handheld programmers (yet). The dealer can program them, for a small fee I'm sure. I had mine dropped 10lbs. They all have to be the same pressure, can't have fronts different from the rears. The system is designed to have a variance of no more than 10 psi. So if you have the BCM programmed for 50psi, it will allow you to go as low as 45 and as high as 55 in the tire without getting a warning.

[Mike2500HD]

Bullydog Speedometer Calibration Tool:

 

V 1.1.5 January 10, 2008

 

- Updated the speedometer tool so that it will work on late 06 -08 lbz and lmm GM diesels

 

 

If I knew someone that had one maybe, but I'm not dropping $600+ for one myself. I'm good with the truck the way it is. It's just irritating that GM won't do it when we all know they can. Probably the darn lawyers getting involved or something..

 

What a bunch of crap!! I only bought my truck last month and I've been driving a GMC since the mid 90's but I wish I read some of this stuff before I bought it. I already have an issue with the 245 75 E tires and the pressure sensor. 80 psi being way too much pressure for an empty 3/4 ton truck. I drive an 06 1 ton at work with 265 75 16 E tires, and it handles like a sports car. It rides a bit stiff but I like it better than the way my 3/4 ton rides. I blame it on the 245's being more flexible in the sidewall, and I was planning to dump the stock tires as soon as I can justify it...and now I hear that GM thinks its a liability issue for me to go to better tires? This all makes me worry about the on-star also. They know how fast your driving, what tire pressure your running, they know exactly what your doing and where. I know this sounds paranoid but in the event you have an accident I bet this information can be discovered by the insurance company lawyers to use against you. Theres no way Im renewing the onstar for the price but I dont even want the technology in my truck. They are out of controll if they are telling you a fraction of an inch of tire diameter is a liability issue! Or that its causing your transmission to slip! This is why Toyota is now the number one manufacturer. I really think we need to start to organize responses to this and threaten suit against them when there refusal to act results in an accident. What the hell? Between corporate weasels, lawyers, insurance company dweebs and polititions we dont have a chance....

 

 

I hear ya man!! As far as them refusing to update my tire size I'm tempted to try another dealership just to see what they say about it. I have no reason to doubt the original dealership, I mean it was money lost to them.

 

The TPMS thing is a bummer though, and again maybe a different dealership would be able to recal the system, for lower pressures. I've got my rears down to 70psi now and it seems a little less harsh, that's with 265's too. I'll probably bring them down to 65psi and see what that does. Since mandated TPMS is new I think it will take a little while for the dealerships to loosen up a little and make adjustments. The question is can they change the tolerances?? If it is possible I'm sure the handheld programmer companies out there will figure it out and make it an option also.

 

Don't give up on your truck and do anything silly like a buy a Toyota! Despite these couple of annoyances I love my truck and wouldn't trade it for anything.

 

Al

 

I dont mean I would buy a Toyota but I'm saying thats why the Japs are really taking over the industry. This TPMS is a reall asset. It should be a great safety tool. But they turned it into a controll issue. Were obviously retarded and cant comprehend such hightech stuff like tires and such...and air... also I dropped the rears to 50 as well as the fronts. with the 245's. Thats where it felt best. Then I kept raising the pressure till the light went out. 65 does it but thats boarderline so at night or when its cool you still get the warning untill the tire warms up. 50 in the front has yet to set the light off. Its supposed to be 15% drop from rated pressure sets the warning off. M.R.

[ursandal]

I agree, the TPMS is a good safety feature and I'm glad it's on the truck. I also have a 08 Jeep Wrangler and it's an issue for alot of folks that put larger tires on 'em and want to run lower pressures or air down when off road. Just something we're all going to have to learn to live with I guess. Unfotunately those of us that are responsible drivers and take care of our vehicle are being lumped in with the 10% that will drive their car to work with no oil and a flat tire...