Operation CHARM: Car repair manuals for everyone.

Component Tests and General Diagnostics

Inspection of HVAC Control Module and Its Circuits

CAUTION: HVAC control module can not be checked by itself.
It is strictly prohibited to connect voltmeter to HVAC control module with connector disconnected from it.


HVAC control module and its circuits can be checked at HVAC control module wiring connector by measuring voltage and pulse signal.

Voltage Check
1. Remove HVAC control module.
2. Connect HVAC control module connector to HVAC control module.
3. Check voltage and/or pulse signal at each terminal of connector connected by referring to HVAC Control Module Voltage Table.






NOTE:
- As each terminal voltage is affected by battery voltage, confirm that it is 11 V or more when ignition switch is ON.
- Voltage with asterisk (*) cannot be measured by voltmeter because it is pulse signal. Check it with oscilloscope if necessary.

HVAC Control Module Voltage Table

HVAC Control Module Voltage Table (Part 1):




HVAC Control Module Voltage Table (Part 2):






Reference waveform No. 1
High and low of CAN communication signals.

Reference Waveform No. 1: