Speed Control - Operation

OPERATION

When speed control is selected by pressing the ON switch, the Powertrain Control Module (PCM) allows a set speed to be stored in its Random Access Memory (RAM) for speed control. To store a set speed, press the SET switch while the vehicle is moving at a speed between 25 - 100 mph (40 - 160 km/h). In order for the speed control to engage, the brakes cannot be applied, and the transmission cannot be in park, neutral or low.
The speed control can be disengaged manually by:
- Pressing the brake pedal
- Pressing the ON/OFF button
- Actuating the cancel function on the lever stalk

NOTE: Pressing the OFF switch or turning off the ignition switch erases the set speed stored in the PCM (Electronic Control Module (ECM) with a diesel engine).

For added safety, the speed control system is programmed to disengage for any of the following conditions:

- An indication of park or neutral
- A rapid increase rpm (indicates the clutch has been disengaged)
- Excessive engine rpm (indicates the transmission may be in a low gear)
- The speed signal increases at a rate of 10 mph (16 km/h) per second (indicates the coefficient of friction between the road surface and tires is extremely low)
- The speed signal decreases at a rate of 10 mph (16 km/h) per second (indicates the vehicle may have decelerated at an extremely high rate)

Once the speed control has been disengaged, actuate the lever stalk up to RES/ACCEL (when the speed is greater than 20 mph (32 km/h) restores the vehicle to the target speed stored in the PCM ( ECM with a diesel engine).

While the speed control is engaged, the driver can increase the vehicle speed by pressing the RES/ACCEL switch. The new target speed is stored in the PCM ( ECM with a diesel engine) when the RES/ACCEL is released. The PCM ( ECM with a diesel engine) also has a tap-up feature in which the vehicle speed increases at a rate of approximately 1 mph (1.6 km/h) for each momentary switch activation of the RES/ACCEL switch.

A tap-down feature is used to decelerate without disengaging the speed control system. To decelerate from an existing recorded target speed, momentarily actuate the lever stalk down when in SET/DECEL. For each switch activation, the speed is lowered approximately 1 mph (1.6 km/h).