INSPECTION PROCEDURE 7: Blower motor power supply system: Diagnosis

WARNING: This page is about a different car, the 2015 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

Required Special Tools:

MB991223: Harness Set
MB992006: Extra Fine Probe

STEP 1. Check blower relay connector C-303 for loose, corroded or damaged terminals, or terminals pushed back in the connector .
Q: Is blower relay connector C-303 in good condition?
- YES: Go to Step 2.
- NO: Repair or replace the connector. Refer to HARNESS CONNECTOR INSPECTION .

STEP 2. Check the blower relay continuity .

Follow the table below to check the blower relay for continuity.

Battery voltage	Tester connection	Specified condition
Not applied	3 - 4	Open circuit
Connect terminal 1 to the positive battery terminal Connect terminal 2 to the negative battery terminal	3 - 4	Less than 2 ohms

Q: Is the blower relay in good condition?

YES: Go to Step 3.
NO: Replace the rear window defogger relay.

Fig 1: Identifying Blower Relay
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

STEP 3. Measure the voltage at blower relay connector C-303 .
1. Disconnect blower relay connector C-303, and measure the voltage at the junction block side.
2. Measure the voltage between terminals 1 and ground.
  - The measured value should be approximately 12 volts (battery positive voltage).
    
    Fig 2: Measuring Voltage Between Terminals 1 And Ground
    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Measure the voltage between terminals 4 and ground.
  - The measured value should be approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts?
- YES: Go to Step 5.
- NO: Go to Step 4.
  
  Fig 3: Measuring Voltage Between Terminals 4 And Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 4. Check the wiring harness between blower relay connector C-303 (terminals 1 and 4) and the fusible link (37) .
NOTE: Also check ETACS-ECU connector C-309 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connector C-309 is damaged, repair or replace the connector as described in HARNESS CONNECTOR INSPECTION .
- Check the blower relay power supply line for open circuit.
Q: Is the wiring harness between blower relay connector C-303 (terminals 1 and 4) and the fusible link (37) in good condition?
- YES: It can be assumed that this malfunction is intermittent. Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS .
- NO: Repair or replace the wiring harness. Refer to HARNESS CONNECTOR INSPECTION .
STEP 5. Check blower relay connector C-113 for loose, corroded or damaged terminals, or terminals pushed back in the connector .
Q: Is blower relay connector C-113 in good condition?
- YES: Go to Step 6.
- NO: Repair or replace the connector. Refer to HARNESS CONNECTOR INSPECTION .
STEP 6. Check the wiring harness between blower relay connector C-303 (terminal 3) and blower motor connector C-113 (terminal 1) .
NOTE: Also check ETACS-ECU connector C-315 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connector C-315 is damaged, repair or replace the connector as described in HARNESS CONNECTOR INSPECTION .
- Check the blower motor power supply line for open circuit.
Q: Is the wiring harness between blower relay connector C-303 (terminal 3) and blower motor connector C-113 (terminal 1) in good condition?
- YES: It can be assumed that this malfunction is intermittent. Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS .
- NO: Repair or replace the wiring harness. Refer to HARNESS CONNECTOR INSPECTION .