The speedometer reading may be inaccurate on some 2015-2017 Express, Savana, Silverado, Sierra, Tahoe, Suburban, Yukon, and Escalade models. (Fig. 7) The speedometer may indicate a lower mph than the vehicle is actually traveling. The inaccurate speedometer reading may occur when drivers use two-pedal driving techniques or when there is a short to the four-wheel drive (4WD) Low switch.
Fig. 7
These conditions may be caused by incorrect initialization of the Utilized (Buffered) Transfer Case Range to Low range. When the transfer case 4WD Low switch is high, it causes the discrepancy between the switch and Utilized (Buffered) Transfer Case Range. When this occurs, the vehicle speed will constantly display 37% of actual vehicle speed (2.7 ratio) until the transmission is shifted to Park or Neutral.
To confirm the condition:
- Start the vehicle.
- Apply the throttle to greater than 7%.
- Shift into Drive.
The speedometer will now be latched at 39% of actual speed until vehicle is shifted to N or P.
If two pedal driving techniques are used during start-up, it may cause the acceleration pedal position to be maintained at value while the transmission is not engaged. The vehicle should not be started with the driver’s foot on the accelerator pedal while shifting into gear.
– Thanks to Richard Renshaw
