Description & Operation
NOTE:
This article includes Cab & Chassis.
- Analog instrument cluster is equipped with magnetic type speedometer, tachometer, fuel, oil pressure, voltage and temperature gauges. When ignition switch is turned to RUN position, SERVICE ENGINE SOON, air bag warning lights, anti-lock brake system, charge system, safety belt, theft indicator (Excursion), wait to start and water in fuel (diesel) will illuminate momentarily for display prove out. Gauges need no calibration and are not individually replaceable. Cluster must be replaced as a unit.
- Fuel sending unit is a variable resistor that has low resistance when fuel level is low and high resistance when fuel level is high. Alternative fuel vehicles use the same fuel gauge, but all readings including gasoline are routed through the compuvalve. Water temperature sensor has high resistance when water temperature is low.
- Oil pressure indicator sender unit contact points open when oil pressure drops below 6 psi (42 kPa). Vehicle speed signal comes from anti-lock brake system module. Gasoline engine vehicles receive tachometer signal from Powertrain Control Module (PCM). Diesel engine vehicles receive tachometer signal from generator.
- SERVICE ENGINE SOON light illuminates when PCM sets a Diagnostic Trouble Code (DTC). Red brake warning light indicates low fluid level, brake malfunction or parking brake not fully released. Yellow brake warning light indicates malfunction, or deactivation of anti-lock brake system. The WATER IN FUEL (diesel only) illuminates when 0.2 pint (100cc) of water has accumulated in fuel filter/water separator.