HVAC Control Module Circuits
Inspection of HVAC Control Module and Its CircuitHVAC control module and its circuits can be checked at HVAC control module wiring couplers by measuring voltage.
CAUTION: HVAC control module can not be checked by itself. It is strictly prohibited to connect voltmeter to HVAC control module with couplers disconnected from it.
Voltage Check
1. Remove HVAC control module referring to HVAC Control Module Removal and Installation:Automatic Type.
2. Check voltage at each terminal.
NOTE: As each terminal voltage is affected by the battery voltage, confirm that it is 11 V or more when ignition switch is ON.
G20-1-G20-17:
G20-18-G20-30:
Reference waveform No. 1
Rear defogger switch or A/C switch signal (1)
Reference waveform No. 2
Serial communication line of BCM (1)
