2023 Silverado 1500 LT 5.3 Speedometer Calibration?

[sutphinboyy]

Hello Everyone,

 

I own a 2023 Silverado 1500 LT 5.3 and I have changed the wheels from the stock 18in premium wheels that came on my truck to 35 x 12.50s. I am aware that my speedometer is off calibration reading  about 5mph slower than it is actually going. IE actual 55mph displays as 50mph. That is not of the biggest concern, but my biggest concern is that the shift points are off and my trucks RPM is consistently in the 2000 - 3000RPM range even going from 54 to 55mph with the cruise control on dictates a gain of about 1000 RPM. I have purchased the Rough Country speedometer calibration tuner, which American Trucks states is compatible with my 1500 Silverado but the truth is that it is not compatible (verified with Rough Country) and they took the return fine. But my question is, is there anything that I can get that will work to correct my shift points and the speedometer both? The main concern is the shift points. 

 

I appreciate the help!

[TrueBlue]

FWIW the service dept. told me that they have no flash ability for the different wheel and tire packages to correct odo/speedo variations. I asked them because my truck came with 17" 255/70's and I had them put 20" 275/60's that came with my trade-in on it. As near as I can figure my speedo is off 3.7mph at 70mph. I don't know why they would tell me they didn't if in fact they do if it would enable them to make money on a flash. They said that the High Country comes with 22" wheels and they're no difference in the ECM(?), even for them.

I don't always believe what service departments tell me, but in this case I don't see any motivation for them to say they don't have the ability to do so, though it is possible the young man I spoke to just didn't know.

Edited February 2, 2024 by TrueBlue

[newdude]

On 1/27/2024 at 3:29 PM, sutphinboyy said:

Hello Everyone,

 

I own a 2023 Silverado 1500 LT 5.3 and I have changed the wheels from the stock 18in premium wheels that came on my truck to 35 x 12.50s. I am aware that my speedometer is off calibration reading  about 5mph slower than it is actually going. IE actual 55mph displays as 50mph. That is not of the biggest concern, but my biggest concern is that the shift points are off and my trucks RPM is consistently in the 2000 - 3000RPM range even going from 54 to 55mph with the cruise control on dictates a gain of about 1000 RPM. I have purchased the Rough Country speedometer calibration tuner, which American Trucks states is compatible with my 1500 Silverado but the truth is that it is not compatible (verified with Rough Country) and they took the return fine. But my question is, is there anything that I can get that will work to correct my shift points and the speedometer both? The main concern is the shift points. 

 

I appreciate the help!

 

 

Yes, put the stock wheels/tires back on.

 

GM will only calibrate to authorized sizes.

  

[newdude]

45 minutes ago, TrueBlue said:

FWIW the service dept. told me that they have no flash ability for the different wheel and tire packages to correct odo/speedo variations. I asked them because my truck came with 17" 255/70's and I had them put 20" 275/60's that came with my trade-in on it. As near as I can figure my speedo is off 3.7mph at 70mph. I don't know why they would tell me they didn't if in fact they do if it would enable them to make money on a flash. They said that the High Country comes with 22" wheels and they're no difference in the ECM(?), even for them.

I don't always believe what service departments tell me, but in this case I don't see any motivation for them to say they don't have the ability to do so, though it is possible the young man I spoke to just didn't know.

 

 

2 ways they can do this. 

 

If you bought acccessory wheel/tire package from GM, GM has a calibration authorization code that allows new programming for the truck.  So from the 17"s or 18"s and you go to stock size 20"s or 22"s, there is a flash for the ECM, cluster, power steering control module and front camera module if equipped.  

 

Option 2.  If in the build and price or order guide your truck could have been ordered with 20" wheels, then GM would allow for a VCI calibration to be performed.  So if your LT crew cab could have been ordered with those 20"s (which it could have) then GM would authorize reprogramming at the customer's expense.  Here is the PI explaining it - MC-10227674-9999.pdf (nhtsa.gov)

Edited February 2, 2024 by newdude

[TrueBlue]

Thanks @newdude. This would mean that the young man in the service department who I spoke to was not aware that there is a flash that can be done to the ECM to calibrate the odo/speedo! Not a big deal for me since I know how much under my speedo is reading, and I have an extended warranty on the truck which will almost certainly expire due to time rather than mileage since I don't typically put a lot of miles on my vehicles.

 

My first '23 was a Sterling Gray LT with the 2.7 turbo, and 275/60R20's Grazen Pocket wheel and tire package (as seen in the picture below). After 700 miles it developed an oil leak at the front of the oil pan. I took the opportunity to trade it in and upgrade to a Glacier Blue 5.3 LT that they didn't have available when I bought the first truck. It came with the 255/70R17's. I negotiated with them to swap the wheels and tires between the trucks before I took delivery of the second truck. So given that this is pretty close to Scenario 1 in your Bulletin I'm assuming that they could flash my ECM. And perhaps with no charge to me?

Edited February 2, 2024 by TrueBlue

[newdude]

4 hours ago, TrueBlue said:

Thanks @newdude. This would mean that the young man in the service department who I spoke to was not aware that there is a flash that can be done to the ECM to calibrate the odo/speedo! Not a big deal for me since I know how much under my speedo is reading, and I have an extended warranty on the truck which will almost certainly expire due to time rather than mileage since I don't typically put a lot of miles on my vehicles.

 

My first '23 was a Sterling Gray LT with the 2.7 turbo, and 275/60R20's Grazen Pocket wheel and tire package (as seen in the picture below). After 700 miles it developed an oil leak at the front of the oil pan. I took the opportunity to trade it in and upgrade to a Glacier Blue 5.3 LT that they didn't have available when I bought the first truck. It came with the 255/70R17's. I negotiated with them to swap the wheels and tires between the trucks before I took delivery of the second truck. So given that this is pretty close to Scenario 1 in your Bulletin I'm assuming that they could flash my ECM. And perhaps with no charge to me?

 

 

There will be a charge. 

 

Option 1 I described only applies to the packages they sell via the GM accessories catalog.  You fall under option 2.   

Edited February 3, 2024 by newdude

[TrueBlue]

Thanks again for the info!

[s10dragracer888]

On 2/2/2024 at 11:27 AM, newdude said:

 

 

2 ways they can do this. 

 

If you bought acccessory wheel/tire package from GM, GM has a calibration authorization code that allows new programming for the truck.  So from the 17"s or 18"s and you go to stock size 20"s or 22"s, there is a flash for the ECM, cluster, power steering control module and front camera module if equipped.  

 

Option 2.  If in the build and price or order guide your truck could have been ordered with 20" wheels, then GM would allow for a VCI calibration to be performed.  So if your LT crew cab could have been ordered with those 20"s (which it could have) then GM would authorize reprogramming at the customer's expense.  Here is the PI explaining it - MC-10227674-9999.pdf (nhtsa.gov)

 

On 2/2/2024 at 9:36 PM, newdude said:

 

 

There will be a charge. 

 

Option 1 I described only applies to the packages they sell via the GM accessories catalog.  You fall under option 2.   

 

On 2/2/2024 at 5:10 PM, TrueBlue said:

Thanks @newdude. This would mean that the young man in the service department who I spoke to was not aware that there is a flash that can be done to the ECM to calibrate the odo/speedo! Not a big deal for me since I know how much under my speedo is reading, and I have an extended warranty on the truck which will almost certainly expire due to time rather than mileage since I don't typically put a lot of miles on my vehicles.

 

My first '23 was a Sterling Gray LT with the 2.7 turbo, and 275/60R20's Grazen Pocket wheel and tire package (as seen in the picture below). After 700 miles it developed an oil leak at the front of the oil pan. I took the opportunity to trade it in and upgrade to a Glacier Blue 5.3 LT that they didn't have available when I bought the first truck. It came with the 255/70R17's. I negotiated with them to swap the wheels and tires between the trucks before I took delivery of the second truck. So given that this is pretty close to Scenario 1 in your Bulletin I'm assuming that they could flash my ECM. And perhaps with no charge to me?

So, I took my truck in to have the VCI wheel swap programming done. The tech at the dealership has been so patient. I went from a 255/70R17 on factory WT steelies to a 275/65R18 on aluminum rim from a ZR2, secondhand. The tech was on the phone with tech-line for what seemed like an eternity. (After waiting 90 minutes to be first in the queue). GM has escalated it up to the highest power they can to see if there is a calibration available. The dealer, tech and I, after deliberating with GM (who is willing to offer the VCI if it’s available) think that the same VCI programming applies to the 17 AND the 18 inch rim, regardless of tire size, due to the minimal nominal difference in size (1” diameter in total). 

 

As far as I can tell, at 60 mph, the speedometer is 1 mph off if at all.

Edited March 8, 2025 by s10dragracer888
Had to fix my grammar and clear up a confusing statement