I’ve filed the following safety issue with the NHTSA, after spending considerable time attempting to explain this safety issue to Chevrolet only to get incoherent answers by people who don’t appear competent enough to understand the problem. If you’ve been in an accident caused by GM’s speed control, it’s possible that this may potentially have come into play. I’ve been able to reproduce this glitch in 2015-2016 Silverado models, however it’s likely to affect any vehicles with the same speed control. It most likely affects the GMC Sierra, as well as other trucks and vehicles using the same speed control system (possibly Yukon, Suburban, Escalade, and Tahoe).
In the case below, speed control acts directly contrary to the way it is stated in the user manual, and how the driver expects it to behave. Chevrolet doesn’t appear to either understand or has dismissed the safety implications below. If you’ve been affected by this, I recommend you contact your attorney.
The final response I received from Chevrolet is to hold the “set” button in rather than press it multiple times – in spite of the fact that their own owner’s manual specifically states that pressing it briefly multiple times will lower the speed:
“To slow down in small increments, briefly press the SET– button. For each press, the vehicle goes about 1.6 km/h (1 mph) slower”
So Chevrolet’s “solution” is, rather than fix cruise control so that it behaves the way it’s documented in the manual, instead to have me change my driving habits to use cruise control in a way that is counter-intuitive and not standard to other vehicles, including other Chevrolet models. It is sad that software bugs like this are among the easiest to fix and issue a recall for, yet also appear to often be the most likely types of problems to be dismissed or rationalized by Chevrolet. In the event this costs someone their life, I wanted this to be documented publicly since Chevrolet has expressed no interest in correcting the problem or issuing a recall.
A CONDITION EXISTS WHERE, AFTER THE DRIVER HAS USED THE GAS PEDAL TO ACCELERATE, THEN HAS REMOVED THEIR FOOT FROM THE PEDAL, THEN PRESSES THE CRUISE “SET” BUTTON IMMEDIATELY OR A BRIEF MOMENT LATER, AND THEN IMMEDIATELY ATTEMPTS TO DECELERATE BY REPEATEDLY PRESSING MINUS “-” ON THE CRUISE CONTROL, THAT THE SPEED CONTROL BECOMES CONFUSED AND DISPLAYS MULTIPLE DIFFERENT SPEEDS, WHILE MAINTAINING THE ORIGINAL SPEED, EVEN THOUGH THE DRIVER BELIEVES THEY ARE DECELERATING. THIS CAN BE REPRODUCED ON ANY 2015-2016 SILVERADO MODEL BY FOLLOWING THESE STEPS: THROTTLE UP AND ACCELERATE (TO PASS, FOR EXAMPLE), REMOVE FOOT FROM ACCELERATOR, THEN IMMEDIATELY PRESS THE “SET” BUTTON, FOLLOWED BY 5-10 PRESSES ON THE DECELERATE “-” BUTTON; THE SPEED WILL SET AT 65, FOR EXAMPLE, THEN FLIP BETWEEN 64, 65, 63, 65, 62, 65, 61, 65, 60, 65, AND SO ON, MAINTAINING SPEED AT 65 EVEN THOUGH THE DRIVER IS INSTRUCTING THE VEHICLE TO DECELERATE AND THE REDUCED SPEED IS TEMPORARILY DISPLAYED. IT MAY TAKE 5-10 SECONDS FOR THE SPEED CONTROL TO CLEAR ALLOWING THE DRIVER TO MAKE CHANGES, HOWEVER THEY WILL STILL BE CRUISING AT 65. DURING THIS PERIOD, THE DRIVER DOES NOT REALIZE THAT THEY WERE NOT DECELERATING AT WHICH POINT THEY MAY TAP THE BRAKES TO DISENGAGE CRUISE, BUT HAVE LOST 5-10 SECONDS OF REFLEX TIME. THIS HAS PRESENTED A DANGEROUS CONDITION WHERE THE DRIVER BELIEVES THEY’RE DECELERATING WHEN TOO QUICKLY APPROACHING ANOTHER VEHICLE, RISKING COLLISION.