HVAC Control Module and Its Circuits Inspection
HVAC Control Module and Its Circuits InspectionCAUTION: 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.
HVAC control module and its circuits can be checked at HVAC control module wiring couplers by measuring voltage.
Voltage Check
1. Remove HVAC control module. Refer to HVAC Control Module Removal and Installation.
2. Connect HVAC control module and body control module couplers to HVAC control module and body control module.
3. Check each terminal voltage with couplers connected by referring to HVAC Control Module Voltage Table.
Terminal arrangement of HVAC control module (viewed from harness side)
HVAC Control Module Voltage Table
1. Reference Waveform No.1
NOTE: The shape of waveform varies with engine coolant temperature.
Measurement terminal: G52-26 to G52-23
Oscilloscope setting:
CH1: 1 V / DIV
TIME: 200 ms / DIV
Measurement condition: Ignition switch turned ON
Waveform at 0 °C (32 °F)
Waveform at 40 °C (104 °F)
Waveform at 80 °C (176 °F)
2. Reference Waveform No.2
NOTE: The shape of waveform varies with outside air temperature.
Measurement terminal G52-13 to G52-23
Oscilloscope setting
CH1: 1 V / DIV
TIME: 40 ms / DIV
Measurement condition: Ignition switch turned ON
Waveform at -20 °C (-4 °F)
Waveform at 0 °C (32 °F)
Waveform at 30 °C (86 °F)
1. Reference Graph No.1