[13B] MULTIPORT FUEL INJECTION (MPI) <4G64> - - TROUBLESHOOTING - SYMPTOM PROCEDURES - Inspection Procedure 26: A/C Switch System | PRINT PAGE / INDEX / PRIOR / NEXT

Inspection Procedure 26: A/C Switch System
OPERATION The battery voltage is applied to the engine-A/T-ECU (terminal No. 83) from the A/C-ECU (terminal No. 4).
FUNCTION When the A/C switch is in "ON" position, A/C switch ON signal is inputted to the engine-A/T-ECU from the A/C-ECU. In response to the signal, the engine-A/T-ECU controls the A/C compressor relay.
PROBABLE CAUSE Failed A/C Failed A/C system Open/short circuit in A/C circuit or loose connector contact Failed engine-A/T-ECU
| DIAGNOSIS PROCEDURE
| STEP 1. Perform voltage measurement at C-112 engine-A/T-ECU connector.
| Measure engine-A/T-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. 83 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? YES: Go to Step 6 . NO: Go to Step 2 .
| STEP 2. Perform voltage measurement at C-06 A/C-ECU connector.
| Measure engine-A/T-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. 4 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 5 . NO: Go to Step 3 .
| STEP 3. Connector check: C-06 A/C-ECU connector and C-110 engine-A/T-ECU connector
| Q: Is the check result normal? YES: Go to Step 4 . NO: Repair.
| STEP 4. Check harness between C-06 A/C-ECU connector and C-110 (terminal No. 83) engine-A/T-ECU connector.
| NOTE: Before checking harness, check intermediate connector C-104, and repair if necessary. Check output line for short circuit. Q: Is the check result normal? YES: Check A/C system (Refer to GROUP 55A - Troubleshooting ). NO: Repair.
| STEP 5. Connector check: C-06 A/C-ECU connector and C-110 engine-A/T-ECU connector
| Q: Is the check result normal? YES: Check intermediate connector C-104, and repair if necessary. If intermediate connector is normal, check and repair harness between C-06 (terminal No. 4) A/C-ECU connector and C-110 (terminal No. 83) engine-A/T-ECU connector. Check output line for open circuit. NO: Repair.
| STEP 6. Connector check: C-110 engine-A/T-ECU connector
| Q: Is the check result normal? YES: Go to Step 7 . NO: Repair.
| STEP 7. MUT-II/III Data List Item 28: 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? YES: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ). NO: Replace engine-A/T-ECU.

[13B] MULTIPORT FUEL INJECTION (MPI) <4G64> - - TROUBLESHOOTING - SYMPTOM PROCEDURES - Inspection Procedure 26: A/C Switch System | PRINT PAGE / INDEX / PRIOR / NEXT

©2004 Mitsubishi Motors Corporation