Hombre XS Space Cab L4-2.2L CPC (1997)
Speedometer Head: Description and Operation
An electric speedometer drive is standard equipment. Integrated circuits control the air core speedometer and stepper motor odometer. Lighting is
provided by removable bulb and socket assemblies that insert into the back of the instrument cluster.
The speedometer system consists of the instrument cluster, Vehicle Speed Sensor (VSS), Powertrain Control Module (PCM) and related wiring.
The one-piece instrument cluster mounts in front of the driver in the instrument panel. It is not serviceable. If diagnosis leads to a malfunctioning
instrument cluster, it must be replaced. Repairs to the instrument cluster can only be performed by an authorized instrument cluster service center.
The PCM changes the analog output from the vehicle speed sensor to a digital signal containing 4000 pulses per mile (PPM) for the instrument cluster.
The PCM is matched to the final drive and tire size of each vehicle. If the final drive or tire size is changed for any reason, the PCM must be updated to
match the new final drive or tire size. If not, the signal will not be accurate for proper speedometer/odometer operation. An incorrect signal can also
affect anti lock brakes, PCM and cruise control systems.
The VSS is a permanent magnet signal generator that sends an analog signal proportional to the propeller shaft speed to the PCM. The VSS mounts to
the transmission housing.
