To some observers it’s a perfect match — a big RV with a muscular engine capable of going the distance together with a versatile, petite and perky, zero-emission runabout with big batteries.
A vacation together beckons but it requires a quick hook up first. Everything lubricated? Check. Properly inflated? Check. The two are hot to trot but as soon as they begin driving away the wheels suddenly grind to a halt. What happened?!
According to GM service bulletin, #17-NA-257: Electronic Park Brake (EPB) Automatically Applies While Dolly Towing, “this condition may be caused when the grade of the car is estimated by the control module to be greater than 9%.”
In other words, when the frontal area becomes elevated to a great enough extent it triggers an automatic and sudden increase in friction. The Bolt EV is turned off when this happens.
The recommended fix is to remove the negative cable connection from the 12V battery until after fully arriving at the destination.
A tell-all video on YouTube documents the surprising and disturbing behavior.