Component Tests and General Diagnostics
Inspection Of HVAC Control Module And Its CircuitHVAC control unit and its circuits can be checked at HVAC control module wiring connector by measuring voltage.
CAUTION: HVAC control unit can not be checked by itself. It is strictly prohibited to connect voltmeter to HVAC control module with connectors disconnected from it.
Voltage and Signal Check
1. Remove HVAC control module.
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 mode of keyless push start system is "ON".
- For "Ignition mode" described in the following table, it means power supply mode in keyless push start system.
For more details of ignition mode, refer to Description of Keyless Engine Start Function.
- Normal voltage of circuits with asterisk (*1) cannot be measured correctly with voltmeter because they are pulse signals. Check them with oscilloscope.
- Normal voltage of circuits with asterisk (*2) are reference values corresponding to when control puts the temperature control actuator at max cool position, air flow control actuator at "VENT" position, air intake control actuator at "REC" position and battery voltage is approx. 12 V.
Reference Waveform
Oscilloscope display
Shown below is typical waveform display provided by oscilloscope
NOTE:
- Display includes the following types of data:
- Waveforms may vary with measurement conditions and vehicle specifications.
LIN communication signal
LIN Communication signal (1):
Measurement condition
- Ignition mode of keyless push start system: "ON"
CAN communication signal CAN
Communication signal (High) (1)
CAN Communication signal (Low) (2):
Measurement condition
- Ignition mode of keyless push start system: "ON"
