Description & Operation
Analog instrument cluster is a Hybrid Electronic Cluster (HEC). Analog instrument cluster contains: speedometer/odometer, tachometer (if equipped), fuel gauge, temperature gauge and warning lights placed in various locations around instrument cluster. See Fig 1 or Fig 2 .
Vehicle options determine which warning indicators are operational. Although instrument panel may be equipped with an indicator it may not apply to this vehicle. Gauges and warning indicators may use outputs from common sensors to carry out their respective functions. Sensor functions should be considered when diagnosing a problem with any gauges and/or warning indicators. Instrument clusters should be replaced as an assembly and not dismantled for repair.
Speedometer, odometer, tachometer and temperature gauge receives information from Powertrain Control Module (PCM) over Standard Corporate Protocol (SCP) BUS. When speedometer does not receive a vehicle speed signal, display defaults to 0.0 MPH. Odometer records total vehicle mileage and is equipped with a trip meter that can be reset by pushing a button. If odometer does not receive information from PCM, display will show all dashes. Tachometer is electronically operated and indicates engine speed of 0 to 8,000 RPM. Tachometer receives a signal through SCP BUS from PCM. If RPM information sent is invalid or missing, instrument cluster will default tachometer to 0.0 MPH. Temperature gauge will default to COLD position if information from PCM is missing or invalid. Malfunction Indicator Light (MIL) illuminates if a Diagnostic Trouble Code (DTC) is received from PCM which affects exhaust emissions.
Seat belt warning indicator is activated by Generic Electronic Module (GEM) when driver seat belt is not fastened. Indicator will go out automatically after 60 seconds even if safety belt has not been fastened. Door ajar indicator is activated by GEM. Door ajar indicator will illuminate when a ground signal is received from a door, or liftgate that is open or ajar.
Fuel gauge and low fuel warning indicator receives information from fuel sending unit, which is a variable resistor that varies ground supply to gauge and is part of fuel pump module. Fuel level input is heavily dampened to allow movement of fuel in tank, and reads when ignition switch is in RUN position. If an invalid signal is received, gauge will default to below EMPTY position. Low fuel warning indicator illuminates when fuel drops to approximately less than 3 gallons. Charge system indicator on 3.0L engines is hard-wired to generator and illuminates when generator output is insufficient to maintain battery charge. On 2.0L Zetec engines, instrument cluster receives a signal from PCM through SCP BUS.
Anti-Lock Brake System (ABS) warning light is hard-wired directly to ABS control module. ABS warning light should come on for 30 seconds and go out (prove out) after ignition is turned to RUN position. A short to voltage, open circuit or ABS failure will illuminate ABS warning indicator. BRAKE warning indicator will illuminate if brake fluid is low or parking brake is set. When ignition switch is set to RUN position, brake warning indicator grounds circuit and runs self-test. Oil pressure warning indicator receives its ground from engine oil pressure sending unit mounted on engine. Oil pressure warning indicator illuminates when ignition is in RUN position. When engine develops oil pressure, circuit to ground opens to turn out oil pressure warning indicator light. Turn signal and high beam indicators receive voltage directly from headlight switch. Indicators illuminate when headlight high beam or turn signal light is illuminated.