RAM 1500 Van V8-5.2L CNG VIN T (1999)
Cruise Control Switch: Description and Operation
DESCRIPTION
Two separate speed control switch modules are mounted on the steering wheel to the left and right side of the driver's airbag module. 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.
OPERATION
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.
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 four switches are: ON/OFF, SET/COAST, CANCEL and RESUME/ACCELERATE.
Refer to Vehicle Speed Control System for further speed control information.