RAM 1500 Truck 2WD V6-3.9L VIN X (1999)
Cruise Control Switch: Description and Operation
SYSTEM OPERATION
Two separate speed control switch modules are mounted on the steering wheel to the left and right side of the driver's airbag module. Within the
two switch modules, five momentary contact switches, supporting seven different speed control functions are used. The outputs from these
switches are filtered into one input. The Powertrain Control Module (PCM) determines which output has been applied through resistive
multiplexing. The input circuit voltage is measured by the PCM to determine which switch function has been selected.
A speed control indicator lamp, located on the instrument panel cluster is energized by the PCM via the CCD Bus. This occurs when speed control
system power has been turned ON, and the engine is running.
The two switch modules are labeled: ON/OFF, SET, RESUME/ACCEL, CANCEL and COAST. Refer to the owner's manual for more
information on speed control switch functions and setting procedures. The individual switches cannot be repaired. If one individual switch fails,
the switch module must be replaced.
SPEED CONTROL SWITCHES-PCM INPUT
Six different speed control functions, using three momentary contact switches, are monitored through this multiplexed input. The resistance
monitored at this input, in combination with the length of time the PCM measures the resistance, determines which switch feature has been
selected. The three switches are: On/Off; Set/Coast, Cancel and Resume/Accelerate.
Refer to Vehicle Speed Control System for further speed control information.
