Gauges

SPEEDOMETER/ODOMETER
The speedometer receives vehicle speed information from the powertrain control module (PCM). The vehicle speed signal is passed through an RC filter to the input of the speedometer/odometer driver integrated circuit (IC), located in the instrument panel cluster. The high-to-low edge of the square wave input triggers the IC to provide a well defined pulse of current to the coil of the speedometer gage. The IC also counts the input transitions and uses this information to drive the stepper motor for both the odometers. The vehicle completes one mile for every 4990 pulses received from the PCM.

There are two odometers in the instrument panel cluster. The odometer above the speedometer pointer shows total mileage since the vehicle was built and cannot be reset. The odometer below the speedometer pointer is a trip odometer which shows total mileage since last reset, and can be reset to zero at any time. The two odometers are not synchronized. This means that even through one of the odometers may advance by a mile/kilometer the other one may or may not advance to the next mile/kilometer at the same time and vice versa.

TACHOMETER
The tachometer is directly controlled by the PCM using a pulse width modulated (PWM) signal based on the signal received from the crankshaft position (CKP) sensor. The PWM signal to the cluster is passed through an RC filter and sent to the tachometer driver IC. The high-to-low edge of the PWM signal triggers the IC to provide a well defined pulse of current to the coil of the tachometer. The engine completes one revolution for every 6 pulses received from the PCM. The PCM monitors circuit 121 for an open, short to ground or short to voltage and will set DTC P1693 if certain parameters are met.

FUEL GAGE
The fuel gage is controlled by the PCM using a PWM signal based on the signal received from the fuel level sensor. The duty cycle of the PWM signal is directly related to the reading of the fuel level sensor. As the duty cycle increases the fuel level reading displayed by the gage will increase. The PWM signal to the cluster is passed through an RC filter and sent to the fuel gage. The PCM monitors circuit 455 for an open, short to ground, or short to voltage and will set DTC PO656 if certain parameters are met.

COOLANT TEMPERATURE GAGE
The coolant temperature gage is controlled by the PCM using a PWM signal based on the signal received from the engine coolant temperature (ECT) sensor. The duty cycle of the PWM signal is directly related to the reading of the coolant temperature gage. As the duty cycle increases the temperature reading displayed by the gage will increase. The PWM signal to the cluster is passed through an RC filter and sent to the coolant temperature gage. The PCM monitors circuit 135 for an open. short to ground or short to voltage and will set DTC P1691 if certain parameters are met.