Inspection Procedure 22: A/C switch system






OPERATION



  • The battery voltage is applied to the engine-ECU (terminal No. 8) from the A/C-ECU.

PROBABLE CAUSES



  • Failed A/C
  • Failed A/C system
  • Open/short circuit in A/C circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Perform voltage measurement at D-213 engine-ECU connector.

  • Measure engine-ECU terminal voltage.
  • Engine: Idling

  • A/C set temperature:

      • Maximum Cool when temperature in cabin is 25°C or more
      Maximum Hot when temperature in cabin is 25°C or less
  • Voltage between terminal No. 8 and earth.
OK
  • System voltage (when A/C is ON)
  • 0.5 V or less (when A/C is OFF)

Q. Is the check result normal?
Go to Step 2 .
Check A/C system (Refer to GROUP 55 - Troubleshooting - Check Chart for Trouble Symptoms ).

STEP 2. Connector check: D-213 engine-ECU connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace.

STEP 3. M.U.T.-III data list

  • Item 25: A/C switch

    • Engine: Idling
    • A/C set temperature:

        • Maximum Cool when temperature in cabin is 25°C or more
        Maximum Hot when temperature in cabin is 25°C or less
OK:
  • ON (when A/C is ON)
  • OFF (when A/C is OFF)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection. (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).