Brake Hold

The brake hold function eases the strain of driving in stop-and-go traffic by allowing the driver to "hold" the brake without constantly applying pressure to the brake pedal. The brake hold function is an extension of hill start aid (HSA) available with Detroit DT12 Transmissions.

To activate the brake hold function, bring the vehicle to a complete stop, then press the brake pedal further toward the floor. The HOLD telltale, shown in Fig. illuminates on the driver display to indicate the function is active and the vehicle's brake lights come on. The driver can then take their foot off the brake pedal without releasing the service brakes.

If the brake pedal is pressed down farther, air is added to the chamber, continuing the brake hold.

To release the brake hold, press the accelerator pedal, engage the park brake, or rapidly apply and release the brake pedal.

The hold function is deactivated when the HSA OFF switch is pressed to disable HSA.

The hold function cannot be engaged if any of the following are true:

• the anti-lock braking system was active in bringing the vehicle to a stop,

• the anti-lock braking system is in a fault state, or

• the vehicle is in reverse gear.

If the hold function is active for four minutes, the window shown in Fig. appears on the ICU warning the driver to engage the park brake. An audible alarm activates at the same time and repeats every minute until the park brake is set.

The same warnings are triggered if the hold function is active and:

• the ignition is turned off without the park brake being set, or

• the brakes are not strong enough to hold the vehicle in place and it starts rolling.

If a door is opened without the park brake being set when the hold function is active, the horn sounds and a visual warning activates on the driver display. If the seat occupancy sensor registers an empty seat under the same conditions, the same warnings are triggered. Warnings cease when the condition that triggered the warning is corrected.