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Home >> Cadillac >> 1987 >> Allante F7/ME9 >> Repair and Diagnosis >> Engine Performance >> System >> Self-Diagnostics >> Self-Diagnostic System >> Diagnostic Modes >> Status Light Display

Status Light Display

NOTE: Operating vehicle in "DIAGNOSTIC (SERVICE) MODE" for extended time periods without engine running or without a battery charger will cause battery to run down and possibly related false diagnostic information, or cause a no start condition. To ensure proper operation, attach a battery charger if vehicle is to be operated in "DIAGNOSTIC (SERVICE) MODE" without engine running for periods longer than 1/2 hour.

While in diagnostic service mode, the lights on the Climate Control Panel (CCP) function buttons indicate status of various operating modes. The different modes of operation are indicated by the light being either on or off. Lights and the mode they represent are as follows:

  1. "OFF" Button

    This light is illuminated when left oxygen sensor indicates a rich exhaust mixture (not enough oxygen). The light will be off when the signal indicates a lean mixture (too much oxygen). It should flicker on and off during warm steady throttle operation to verify that the oxygen sensor is providing signals to the ECM and that the ECM is in closed loop operation.

  2. "ECON" Button

    This light is illuminated when right oxygen sensor indicates a rich exhaust mixture (not enough oxygen). The light will be off when the signal indicates a lean mixture (too much oxygen). It should flicker on and off during warm steady throttle operation to verify that the oxygen sensor is providing signals to the" ECM and that the ECM is in closed loop operation.

  3. "AUTO" Button

    This light is illuminated when ECM is operating in "closed loop" fuel control mode. This light should come on when the coolant temperature and oxygen sensors reach normal operating temperature.

  4. "FRONT DEFOG"

    This light is illuminated whenever ECM allows A/C clutch engagement through the A/C clutch relay .

  5. "REAR DEFOG"

    This light indicates when ECM is commanding the Viscous Converter Clutch (VCC) to engage .

  6. "°C"

    This status indicator is turned on whenever ECM senses that 3rd gear pressure switch is open. The light should be on while in 3rd gear operation.

  7. "°F"

    This status indicator is turned on whenever ECM senses that 3rd and 4th gear pressure switches are open. The light should be on while in 4th gear operation and ECM had received a 3rd gear input signal.

  8. "°E"

    This status indicator is turned on whenever ECM senses that 4th gear pressure switch is open, but not 3rd gear switch. This light should be on while in 4th gear operation and ECM had not received a 3rd gear input signal.

  9. "LO FAN"

    This status indicator is turned on whenever BCM is commanding A/C-DEF mode door to divert airflow to A/C outlets (as in A/C or normal purge modes). This light will be off whenever CCP system is in "heater", "intermediate", "defrost" and "cold purge" modes.

  10. "NORM FAN"

    This status indicator is turned on whenever BCM is commanding heater water valve to block coolant flow through heater core. The light should remain off except when air-mixture door is being commanded to max A/C position.
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