Code No. P1AC1: Main Battery Cooling Fan Failed (driving abnormal)










TROUBLE JUDGMENT
Check Conditions
  • The main battery cooling fan relay is turned ON.
  • The following diagnosis codes are not set.

  1. P1A47: Power supply of main battery cooling fan relay abnormal (short circuits to power supply system, open circuits)
  2. P1A4E: Power supply of main battery cooling fan relay abnormal (short circuits to earth system)
Judgement Criterion
  • For more than 5 seconds, the PWM output signal of the main battery cooling fan is 10 % (while the fan is being driven). The output of the rotational speed is less than 2.0 V (less than 1,645 r/min or equivalent).

FAIL-SAFE AND BACKUP FUNCTION

  • Not available

PROBABLE CAUSES

  • The main battery cooling fan relay is failed.
  • The main battery cooling fan is failed.
  • Open circuits of main battery cooling fan relay circuit, short circuits to earth or damage; poor contact of connector.
  • Open circuits of main battery cooling fan circuit, short circuits to earth or damage; poor contact of connector.
  • The BMU is failed.

DIAGNOSIS PROCEDURE


STEP 1. Connector check: A-115X main battery cooling fan relay connector

Q. Is the check result normal?
Go to Step 2 .
Repair.

STEP 2. Check main battery cooling fan relay itself.

  • Check main battery cooling fan relay itself (Refer to ).

Q. Is the check result normal?
Go to Step 3 .
Replace the main battery cooling fan relay.

STEP 3. Perform voltage measurement at A-115X main battery cooling fan relay

  • Remove the relay, and measure at relay box side.
  • Voltage between terminal No. 4 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 4 .

    Check and repair harness between auxiliary battery and A-115X (terminal No. 4) main battery cooling fan relay connector.

    • Check power supply line for open circuit, short circuit to earth

STEP 4. Connector check: C-14 main battery cooling fan connector

Q. Is the check result normal?
Go to Step 5 .
Repair.

STEP 5. Perform voltage measurement at C-14 main battery cooling fan connector

  • Disconnect connector, and measure at harness side.
  • Remove the A-115X main battery cooling fan relay, and short-circuit the terminal 4 - 3 at the relay box side.
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6 .

    Check intermediate connector A-107, and repair if necessary. If intermediate connector is normal, check and repair harness between A-115X (terminal No. 3) main battery cooling fan relay connector and C-14 (terminal No. 1) main battery cooling fan connector.

    • Check output line for open circuit, short circuit to earth.

STEP 6. Perform resistance measurement at C-14 main battery cooling fan connector

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 4 and earth.
OK: Continuity (2 Ω less)

Q. Is the check result normal?
Go to Step 7 .

    Check intermediate connector C-104, and repair if necessary. If intermediate connector is normal, check and repair harness between C-14 (terminal No. 4) main battery cooling fan connector and body earth.

    • Check earthing line for open circuit and damage.

STEP 7. Check harness between auxiliary battery and A-115X (terminal No. 4) main battery cooling fan relay connector

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 8 .
Repair.

STEP 8. Check harness between A-115X (terminal No. 3) main battery cooling fan relay connector and C-14 (terminal No. 1) main battery cooling fan connector
note Before checking harness, check intermediate connector C-107, and repair if necessary.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 9 .
Repair.

STEP 9. Perform PWM signal wave pattern measurement at main battery cooling fan (Using an oscilloscope)



  • Use special tool test harness (MB991658) to connect C-14 main battery cooling fan connector, and measure at pick-up harness.
  • For several seconds right after starting the regular charge.
  • Voltage between terminal No. 2 and earth.
OK: The wave pattern must be the same as that described in Inspection Procedure Using an Oscilloscope ().

Q. Is the check result normal?
Go to Step 14 .
Go to Step 10 .

STEP 10. Connector check: C-107 BMU connector

Q. Is the check result normal?
Go to Step 11 .
Repair.

STEP 11. Check harness between C-14 (terminal No. 2) main battery cooling fan connector and C-107 (terminal No. 13) BMU connector
note Before checking harness, check intermediate connector C-102, and repair if necessary.

  • Check signal line for open circuit, short circuit to earth and damage.

Q. Is the check result normal?
Go to Step 12 .
Repair.

STEP 12. M.U.T.-III diagnosis code

Q. Is the diagnosis code set?
Go to Step 13 .
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 13. After replacing the BMU, reconfirm the diagnosis code.

  • After replacing the BMU, reconfirm whether the diagnosis codes are set.

Q. Is the diagnosis code set?
Replace the main battery.
Check end.

STEP 14. Perform voltage measurement at C-107 BMU connector

  • Measure BMU terminal voltage.
  • Right after starting the regular charge.
  • Voltage between terminal No. 21 and earth.
OK: 2 V or more → 1 V or less (After several seconds elapse)

Q. Is the check result normal?
Go to Step 16 .
Go to Step 15 .

STEP 15. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 32: Main battery cooling fan rotational speeds

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 BMU.

STEP 16. Connector check: C-107 BMU connector

Q. Is the check result normal?
Go to Step 17 .
Repair.

STEP 17. Check harness between C-14 (terminal No. 3) main battery cooling fan connector and C-107 (terminal No. 21) BMU connector
note Before checking harness, check intermediate connector C-102, and repair if necessary.

  • Check output line for open circuit, short circuit to earth and damage.

Q. Is the check result normal?
Go to Step 18 .
Repair.

STEP 18. M.U.T.-III diagnosis code

Q. Is the diagnosis code set?
Replace the main battery.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).