TROUBLESHOOTING STRATEGY
Use these steps to plan your diagnostic strategy. If you follow them carefully, you will be sure to find most of the engine cooling faults.
- Gather information from the customer.
- Verify that the condition described by the customer exists.
- Find and repair the malfunction by following the «SYMPTOM CHART»(ref-183619-S30720647462005081800000) .
- Verify that the malfunction is eliminated.
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- STEP 1. Check for coolant leaks. WARNING: When pressure testing the cooling system, slowly release cooling system pressure to avoid getting burned by hot coolant. CAUTION: Be sure to completely clean away any moisture from the places checked. When the tester is removed, be careful not to spill any coolant. When installing and removing the tester and when testing, be careful not to deform the filler neck of the radiator. Check that the coolant level is up to the filler neck. Install a radiator tester and apply 160 kPa (23 psi) pressure, and then check for leakage from the radiator hose or connections. Q: Is leakage present from the radiator hose or connections? YES: Repair or replace the appropriate part, then go to Step 2. NO: There is no action to be taken.
- STEP 2. Retest the system. Q: It there still coolant leakage? YES: Return to Step 1 . NO: The procedure is complete.
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- STEP 1. Remove the radiator cap and check for coolant contamination. Q: Is the coolant contaminated with rust and oil? YES: Replace it. Refer to «ENGINE COOLANT REPLACEMENT»(ref-183619-S14989498372005081800000) . NO: There is no action to be taken. Go to Step 2.
- STEP 2. Check the radiator cap valve opening pressure. NOTE: Be sure that the cap is clean before testing. Rust or other foreign material on the cap seal will cause an improper reading. Use a cap adapter to attach the cap to the tester. Increase the pressure until the gauge indicator stops moving. Minimum limit: 83 kPa (12 psi) Standard value: 93 - 123 kPa (14 - 18 psi) Q: Does the reading remain at or above the minimum limit? YES: Go to Step 3. NO: Replace the radiator cap. Then go to Step 5 .
- STEP 3. Check thermostat operation. Refer to «INSTALLATION SERVICE POINTS»(ref-183619-S27939862402005081800000) . Q: Does the thermostat operate correctly? YES: Go to Step 4. NO: Replace the thermostat, then go to Step 5 .
- STEP 4. Check the drive belt for slippage or damage. Refer to «SPECIFICATIONS & DRIVE BELT ROUTING - EXCEPT»(ref-166737) Q: Is the drive belt loose or damaged? YES: Adjust or replace the drive belt, then go to Step 5. NO: There is no action to be taken.
- STEP 5. Retest the system. Check the coolant temperature gauge. Q: Is the coolant temperature abnormally high? YES: Return to Step 2. NO: The procedure is complete.
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TROUBLESHOOTING HINTS
- Malfunction of fusible link
- Malfunction of fan control relay
- Malfunction of MFI relay
- Malfunction of radiator fan motor
- Malfunction of condenser fan motor
- Malfunction of fan controller
- Malfunction of ECM < M/T > or PCM < A/T >
- Damaged wiring harness or connector
DIAGNOSIS
Required Special Tool
- MB991223: Harness Set
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- STEP 1. Check the circuit at fan controller connector A-17 (terminal 3). Disconnect fan controller connector A-17, and measure at the harness side connector. Measure the voltage between terminal number 3 and ground. When the ignition switch is turned to the "ON" position, voltage should measure battery positive voltage. Q: Is there voltage battery positive voltage when the ignition switch is turned to the "ON" position? YES: Go to Step 8 . NO: Go to Step 2.
- STEP 2. Check the fan control relay. Refer to «FAN CONTROL RELAY CONTINUITY CHECK»(ref-183619-S25099848082005081800000) . Q: Is the fan control relay in good condition? YES: Go to Step 3. NO: Replace it, then go to Step 1 .
- STEP 3. Check the MFI relay. Refer to «FUEL PUMP RELAY & MFI RELAY»(ref-152080-S13017408082003011300000) . Q: Is the MFI relay in good condition? YES: Go to Step 4. NO: Replace it, then go to Step 1 .
- STEP 4. Check for harness damage between fusible link number 2 and fan control relay connector A-09X (terminal 4). Q: Are the harness wires between fusible link number 2 and fan control relay connector A-10X damaged? YES: Repair or replace them, then go to Step 13 . NO: Go to Step 5.
- STEP 5. Check for harness damage between fan control relay connector A-09X (terminal 2) and fan controller connector A-17 (terminal 3). Q: Are the harness wires between fan control relay connector A-09X (terminal 2) and fan controller connector A-17 (terminal 3) damaged? YES: Repair or replace them, then go to Step 13 . NO: Go to Step 6.
- STEP 6. Check for harness damage between MFI relay connector B-12X and fan control relay connector A-09X. NOTE: After inspecting intermediate connector A-13 terminal 8 and joint connector C-105 terminal 33, 28 inspect the wires. If intermediate connector A-13 and joint connector C-105 are damaged, repair or replace them. . Q: Are the harness wires between MFI relay connector B-12X (terminal 4) and fan control relay connector A-09X (terminal 1) damaged? YES: Repair or replace them, then go to Step 13 . NO: Go to Step 7.
- STEP 7. Check for harness damage between fan control relay connector A-09X (terminal 3) and ground. Q: Are the harness wires between fan control relay connector A-09X (terminal 3) and ground damaged? YES: Repair or replace them, then go to Step 13 . NO: Go to Step 8.
- STEP 8. Check the circuit at fan controller connector A-17 (terminal 1). Disconnect fan controller connector A-17, and measure at the harness side connector. Measure the resistance between terminal number 1 and ground. Q: Is the resistance less than 2 ohms? YES: Go to Step 10 . NO: Go to Step 9.
- STEP 9. Check the harness wire between fan controller connector A-17 and ground. Q: Are the harness wires between fan controller connector A-17 and ground damaged? YES: Repair or replace them, then go to Step 13 . NO: Go to Step 10.
- STEP 10. Measure the output circuit voltage at ECM connector C-121 < M/T > (terminal 21) or PCM connector C-120 < A/T > (terminal 18) by backprobing. Do not disconnect ECM connector C-121 < M/T > or PCM connector C-120 < A/T >. Start the engine and allow it to idle. Measure the voltage between terminal number 21 < M/T > or 18 < A/T > and ground by back probing. Q: Is the voltage 0.7 volt or more when the radiator fan is operating? YES: Go to Step 12 . NO: Go to Step 11.
- STEP 11. Check the harness wire between ECM connector C-121 < M/T > or PCM connector C-120 < A/T > and fan controller connector A-30. NOTE: If intermediate connector A-13 terminal 1 is damaged, repair or replace it. . Q: Are the harness wires between ECM connector C-121 < M/T > (terminal 21) or PCM connector C-120 < A/T > (terminal 18) and fan controller connector A-17 (terminal 2) damaged? YES: Repair or replace them, then go to Step 13 . NO: Go to Step 12.
- STEP 12. Check the fan controller at ECM connector C-121 < M/T > or PCM connector C-120 < A/T >. Disconnect ECM connector C-121 < M/T > or PCM connector C-120 < A/T >. Turn the ignition switch to the "ON" position. Q: Do the radiator fan motor and condenser fan motor operate? YES: Replace the PCM. Then go to Step 13. NO: Replace the fan controller. Then go to Step 13.
- STEP 13. Check the symptoms. Q: Do the radiator fan and condenser fan operate correctly? YES: The procedure is complete. NO: Return to Step 1.
INSPECTION PROCEDURE 4: Radiator Fan and Condenser Fan do not Change Speed or Stop
Note. If the engine coolant temperature reaches 110°C (230°F) or higher, the radiator fan control runs the radiator fan for up to 5 minutes even after the ignition switch is turned to the "LOCK" (OFF) position [the fan stops its rotation when the engine coolant temperature decreases to 110°C (230°F) or lower.]
Radiator Fan and Condenser Fan Drive Circuit
Refer to INSPECTION PROCEDURE 3: Radiator Fan and Condenser Fan do not Operate .
- Malfunction of fan control relay
- Malfunction of fan controller
- Malfunction of ECM < M/T > or PCM < A/T >
Required Special Tool
- MB991223: Harness Set
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- STEP 1. Check the fan control relay. Refer to «FAN CONTROL RELAY CONTINUITY CHECK»(ref-183619-S25099848082005081800000) . Q: Is the fan control relay in good condition? YES: Go to Step 2. NO: Replace the part, then go to Step 6 .
- STEP 2. Check the harness wire between fan control relay connector A-09X (terminal 2) and fan controller connector A-17 (terminal 3). Q: Are the harness wire between fan control relay connector A-09X (terminal 2) and fan controller connector A-17 (terminal 3) damaged? YES: Repair or replace the part, then go to Step 6 . NO: Go to Step 3.
- STEP 3. Measure the output circuit voltage at ECM connector C-121 < M/T > (terminal 21) or PCM connector C-120 < A/T > (terminal 18) by backprobing. Do not disconnect ECM connector C-121 < M/T > or PCM connector C-120 < A/T >. Start the engine and run it at idle. [Engine coolant temperature: 80°C (176°F) or less] Measure the voltage between terminal number 21 < M/T > or 18 < A/T > and ground by backprobing. Q: Is the voltage 0 - 0.3 volt when the radiator fan is not operating? YES: Go to Step 6 . NO: Go to Step 4.
- STEP 4. Check the harness wire between ECM connector C-121 < M/T >or PCM connector C-120 < A/T > and fan controller connector A-17. NOTE: If intermediate connector A-13 terminal 1 is damaged, repair or replace it. . Q: Are the harness wires between ECM connector C-121 < M/T > (terminal 21) or PCM connector C-120 < A/T > (terminal 18) and fan controller connector A-17 (terminal 2) damaged? YES: Repair or replace them, then go to Step 6 . NO: Go to Step 5.
- STEP 5. Check the fan controller at ECM connector C-121 < M/T >or PCM connector C-120 < A/T >. Disconnect ECM connector C-121 < M/T > or PCM connector C-120 < A/T >. Pull out the terminal number 21 < M/T > or 18 < A/T > and connect it to the body ground. Reconnect ECM connector C-121 < M/T > or PCM connector C-120 < A/T > with pin 21 < M/T > or 18 < A/T > still removed. Turn the ignition switch to the "ON" position. Q: Do the radiator fan motor and condenser fan motor stop? YES: Replace the ECM < M/T > or PCM < A/T >. Then go to Step 6. NO: Replace the fan controller. Then go to Step 6.
- STEP 6. Check the symptoms. Q: Do the radiator fan and condenser fan operate correctly? YES: The procedure is complete. NO: Return to Step 1.
INSPECTION PROCEDURE 5: Radiator Fan does not Operate
Radiator Fan and Condenser Fan Drive Circuit
Refer to INSPECTION PROCEDURE 3: Radiator Fan and Condenser Fan do not Operate .
- Malfunction of radiator fan motor
- Malfunction of fan controller
- STEP 1. Check the radiator fan motor. Refer to «REMOVAL SERVICE POINTS»(ref-183619-S35930592242005081800000) . Q: Is the radiator fan in good condition? YES: Go to Step 2. NO: Replace the radiator fan motor, then go to Step 3 .
- STEP 2. Check the fan controller. Q: Is the fan controller in good condition? YES: Go to Step 3. NO: Replace the fan controller, then go to Step 3.
- STEP 3. Check the symptoms. Q: Does the radiator fan operate correctly? YES: The procedure is complete. NO: Return to Step 1.
INSPECTION PROCEDURE 6: Condenser Fan does not Operate
Radiator Fan and Condenser Fan Drive Circuit
Refer to INSPECTION PROCEDURE 3: Radiator Fan and Condenser Fan do not Operate .
- Malfunction of condenser fan motor
- Malfunction of fan controller
- STEP 1. Check the condenser fan motor. Refer to CONDENSER FAN MOTOR CHECK . Q: Is the condenser fan motor in good condition? YES: Go to Step 2. NO: Replace the condenser fan motor, then go to Step 3 .
- STEP 2. Check the fan controller. Q: Is the fan controller in good condition? YES: Go to Step 3. NO: Replace the fan controller, then go to Step 3.
- STEP 3. Check the symptoms. Q: Does the condenser fan operate correctly? YES: The procedure is complete. NO: Return to Step 1.