STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
(1) caution | To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III)
."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the CAN bus line found to be normal?
Go to Step 2. Repair the CAN bus lines (Refer to GROUP 54C, precautions on how to repair the CAN bus lines ).
STEP 2. Using scan tool MB991958, read the diagnostic trouble code.
Check if an A/C control panel DTC is set.(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Refer to Diagnostic Trouble Code Chart . Go to Step 3.
STEP 3. Check A/C compressor and clutch assembly connector B-115 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
STEP 4. Check the A/C compressor clutch operation.
STEP 5. Check A/C compressor clutch relay connector A-20X for loose, corroded or damaged terminals, or terminals pushed back in the connector.
STEP 6. Check the A/C compressor clutch relay continuity.
STEP 7. Check engine control module connector B-27 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
STEP 8. Measure the voltage at A/C compressor and clutch assembly connector B-115.
(1) Disconnect A/C compressor and clutch assembly connector B-115 and measure the voltage at the wiring harness side.
(2) Disconnect engine control module connector B-27 and ground harness side terminal No.102.
(3) Turn the ignition switch to the "ON" position.
(4) A/C compressor and clutch assembly connector B-115 terminal 1 and ground.- The measured value should be approximately 12 volts (battery positive voltage).
Is the measured voltage approximately 12 volts?
Go to Step 13. Go to Step 9.
STEP 9. Measure the voltage at A/C compressor clutch relay connector A-20X.
(1) Disconnect A/C compressor clutch relay connector A-20X and measure the voltage at the relay box side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 4 and ground.- The measured value should be approximately 12 volts (battery positive voltage).
(4) Measure the voltage between terminal 2 and ground.- The measured value should be approximately 12 volts (battery positive voltage).
Is the measured voltage approximately 12 volts?
Go to Step 11. Go to Step 10.
STEP 10. Check the wiring harness between A/C compressor clutch relay connector A-20X (terminals 2 and 4) and the fusible link (36).
STEP 11. Check the wiring harness between A/C compressor clutch relay connector A-20X (terminal 3) and A/C compressor and clutch assembly connector B-115 (terminal 1).
STEP 12. Check the wiring harness between engine control module connector B-27 (terminal 102) and A/C compressor clutch relay connector A-20X (terminal 1).
STEP 13. Replace the A/C control panel.