Status Light Indicators
During self-diagnostics, the status light display on ECC Panel or CRT monitor is used to indicate switchable parameter status. Each parameter status is indicated by its status light being turned ON or OFF. Status light indicators are relative to system level being tested (BCM or ECM). See Fig 1 .
The following are brief summaries of each systems status light indicators, starting with the ECM status light indicators:
- LOOP light (CRT equipped) or HIGH light (ECCP equipped) is ON when ECM is in closed loop fuel control. Light comes ON only after coolant and O2 sensors reach operating temperature.
- TCC light (CRT equipped) or MED light (ECCP equipped) only indicates whether operation is enabled or disabled by ECM. Actual working operation depends on TCC system being in working order.
- Oxy light (CRT equipped) or LOW light (ECCP equipped) stays ON when oxygen sensor signals rich exhaust condition to ECM. Light will flash ON and OFF during warm engine, steady throttle, and proper fuel mix condition.
- EGR light (CRT equipped) or LOWER ARROW light (ECCP equipped) is ON when ECM is directing one of the 3 EGR solenoids to be ON. Light will be OFF if no EGR solenoids are ON as during idle condition.
- 4th Gear light (CRT equipped) or OFF light (ECCP equipped) will be ON when ECM senses 4th gear pressure switch open. Light should only be on in 4th gear.
- 3rd Gear light (CRT equipped) or AUTO light (ECCP equipped) will be ON when ECM senses 3th gear pressure switch open. Light should only be on in 3rd or 4th gear.
- 2nd Gear light (CRT equipped) or "°C" light (ECCP equipped) will be ON when ECM senses 2nd gear pressure switch open. Light should only be on in 2nd, 3rd or 4th gear.
- A/C Compressor Command UPPER ARROW (ECCP equipped) or COMP light (CRT equipped) will be ON only when ECM allows A/C clutch engagement through A/C relay. Light will also be ON if BCM requests ECM to turn clutch ON during test sequence. Light should be OFF if ECM commands disengagement.
The following are brief summaries of BCM system status light indicators:
- PRESS light (CRT equipped) or LOWER ARROW light (ECCP equipped) will be ON if BCM senses low refrigerant pressure switch is open. Light will remain OFF if A/C system is fully charged and operational. (However, light will come ON when outside vehicle ambient temperature is less than -5°F (-21°C), this is due to temperature-pressure relationship of R-12 refrigerant.)
- OFF light (ECCP equipped) or REC light (CRT equipped) will be ON when BCM commands air recirculation.
- MED light (ECCP equipped) or A/C light (CRT equipped) will be ON when BCM commands air flow out A/C vents. Light should also be ON in A/C and BI/LEVEL modes.
- AIR UP light (CRT equipped) or LOW light (ECCP equipped) will be ON when BCM commands air flow out defroster outlets. Light should also be ON in defrost and A/C modes.
- AIR DOWN light (CRT equipped) or HIGH light (ECCP equipped) will be ON when BCM commands air flow out floor outlets. Light should be ON in heater mode.
- Left side AUTO light (ECCP equipped) or COMP light (CRT equipped) will be ON when BCM requests ECM to engage A/C compressor clutch.