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Cooling Fan Malfunction

NOTE: The following test procedures are for DTCs P0481, P1474 and P1479.
Fig 1: Cooling Fan Malfunction Detection Condition Possible Cause
G03723739Courtesy of MAZDA MOTORS CORP.
Fig 2: Cooling Fan Malfunction Electronic Chart
G03723740Courtesy of MAZDA MOTORS CORP.
COOLING FAN MALFUNCTION INSPECTION/ACTION CHART

STEP INSPECTION ACTION
1
  • Was PCM Quick Test performed? 
 Yes For Continuous Memory DTC P0481, Go to step 8.
For Continuous Memory DTC P1474, Go to step 10.
For Continuous Memory DTC P1477, Go to step 12.
For Continuous Memory DTC P1479, Go to step 14.
For DTC 1479 (3.0L), Go to step 7.
For all others, Go to next step.
No Perform PCM Quick Test. See PCM QUICK TEST  .
2 CHECK VPWR (IGN START/RUN) VOLTAGE TO APPLICABLE FAN RELAY
  • Disconnect appropriate fan control relay:
    • DTC 1474: LFC
    • DTC 1477: MFC
    • DTC 1479: HFC
  • Key ON, Engine OFF (KOEO).
  • Measure VPWR (IGN START/RUN) circuit voltage at the applicable fan control relay harness connector.
  • Is voltage greater than 10.5 volts? 
 Yes Go to next step.
No Repair open VPWR (IGN START/RUN) circuit to the applicable fan control relay.
Go to step 16.
3 CHECK FOR LFC, MFC OR HFC CIRCUIT CYCLING
  • Connect a non-powered test light between the VPWR circuit and the LFC, MFC or HFC circuit at the applicable fan control relay harness connector.
  • Using the WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Select Output Test Mode.
    NOTE:
    • Commanding the low speed fan (LFC PID) on will also command the medium speed fan (MFC PID) output on if MFC PID is not available.
  • While observing the test light, command the appropriate cooling fan (LFC, MFC or HFC PIDs) speed on and off.
  • Does the test light turn on and off when the cooling fan output is commanded on and off? 
 Yes Replace appropriate fan control relay.
Go to step 16.
No Repeat test step to verify results. If results are still the same, remove test light.
Key OFF.
Go to next step.
4 CHECK LFC, MFC OR HFC CIRCUIT FOR SHORT TO POWER IN HARNESS
  • Disconnect PCM.
  • Key ON, Engine OFF (KOEO).
  • Measure voltage between the LFC, MFC or HFC circuit at the applicable fan relay harness connector and ground.
  • Is voltage less than 1.0 volt? 
 Yes Go to next step.
No Repair short circuit.
Go to step 16.
5 CHECK LFC OR HFC CIRCUIT FOR SHORT TO GROUND IN HARNESS
  • Key OFF.
  • Disconnect WDS or equivalent tester.
  • Measure resistance between the LFC, MFC or HFC circuit at the applicable fan control relay harness connector and ground.
  • Is resistance greater than 10K ohms? 
 Yes Go to next step.
No Repair short circuit.
Go to step 16.
6 CHECK FOR OPEN LFC, MFC OR HFC CIRCUIT
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance of LFC, MFC or HFC circuit between PCM test pin and the appropriate fan control relay harness connector.
  • For 2.3L:
    • LFC, PCM test pin C39
    • MFC, PCM test pin C17
    • HFC, PCM test pin C38
  • For 3.0L:
    • LFC, PCM test pin C39
    • HFC, PCM test pin C38
  • Is resistance less than 5.0 ohms? 
 Yes Replace PCM, see POWERTRAIN CONTROL MODULE (PCM) .
Go to step 16.
No Repair open circuit.
Go to step 16.
7 CHECK IGNITION START/RUN CIRCUIT VOLTAGE TO HIGH SPEED FC RELAY #1
  • Disconnect high speed FC relay #1 (MAIN FAN, in PDB).
  • Key ON, Engine OFF (KOEO).
  • Measure VPWR (IGN START/RUN) circuit voltage at the applicable fan control relay harness connector.
  • Is voltage greater than 10.5 volts? 
 Yes Go to next step.
No Repair open IGN START/RUN circuit.
Go to step 16.
8 CHECK FOR HFC CIRCUIT CYCLING AT HIGH SPEED FC RELAY #1
  • Connect a non-powered test light between the VPWR circuit and the LFC, MFC or HFC circuit at the applicable fan control relay harness connector.
  • Using the WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Select Output Test Mode.
  • While observing the test light, command the high speed cooling fan (using HFC PID) on and off.
  • Does the test light turn on and off when the cooling fan output is commanded on and off? 
 Yes Replace high speed FC relay #1.
Go to step 16.
No Leave test light connected.
Go to next step.
9 CHECK FOR HFC CIRCUIT CYCLING WITH HIGH SPEED FC RELAY #2 DISCONNECTED
  • Disconnect high speed FC relay #2 (ADD FAN 2, in PDB).
  • While observing the test light, command the high speed cooling fan (using HFC PID) on and off.
  • Does the test light turn on and off when the cooling fan output is commanded on and off? 
 Yes Replace high speed FC relay #2.
Go to step 16.
No Go to step 4 to diagnose the HFC circuit. Make checks at the high speed FC relay #1 harness connector.
10 CHECK LOW SPEED FAN CONTROL (LFC) CIRCUIT FOR OPEN OR SHORT TO POWER
  • Verify A/C and defrost are off.
  • Disconnect the cooling fan connectors.
  • Connect a non-powered test light between the (LOW) FAN PWR circuit and ground circuit at the cooling fan harness connector.
    • For 2.3L, use driver's side fan.
    • For 3.0L, use passenger's side fan.
  • Key ON, Engine OFF (KOEO).
  • Using the WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Select Output Test Mode.
  • Command low speed fan (using LFC PID) on.
  • Observe the test light for an indication of a fault while completing the following (the lamp will turn off when a fault is detected, indicating an open or short to power):
    • Shake, wiggle and bend the LFC circuit between the PCM and low speed FC relay.
    • Shake, wiggle and bend the VPWR (IGN START/RUN) circuit to the low speed FC relay.
    • Lightly tap on the low speed FC relay to simulate road shock.
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to step 16.
No Go to next step.
11 CHECK LFC CIRCUIT FOR SHORT TO GROUND
  • Command low speed fan (using LFC PID) off.
  • Observe the test light for an indication of a fault while completing the following (the lamp will turn on when a fault is detected, indicating LFC circuit short to ground):
    • Shake, wiggle and bend the LFC circuit between the PCM and low speed FC relay.
    • Lightly tap on the low speed FC relay to simulate road shock.
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to step 16.
No The problem is intermittent, go to INTERMITTENT PINPOINT TEST .
12 CHECK MEDIUM SPEED FAN CONTROL (MFC) CIRCUIT FOR OPEN OR SHORT TO POWER
  • Verify A/C and defrost are off.
  • Disconnect the cooling fan connectors.
  • Connect a non-powered test light:
    • Connect the test light between the MEDIUM FAN PWR circuit and ground circuit at the passenger-side cooling fan harness connector.
  • Key ON, Engine OFF (KOEO).
  • Using the WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Select Output Test Mode.
    NOTE:
    • Commanding the low speed fan (LFC PID) on will also command the medium speed fan (MFC PID) output on if MFC PID is not available.
  • Command medium speed fan (using LFC or MFC PID) on.
  • Observe the test light for an indication of a fault while completing the following (the lamp will turn off when a fault is detected, indicating an open or short to power):
    • Shake, wiggle and bend the MFC circuit between the PCM and medium speed FC relay.
    • Shake, wiggle and bend the VPWR (IGN START/RUN) circuit to the medium speed FC relay.
    • For 2.3L, lightly tap on the medium speed FC relay to simulate road shock.
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to step 16.
No Go to next step.
13 CHECK MFC CIRCUIT FOR SHORT TO GROUND
  • Command low speed fan (using LFC or MFC PID) off.
  • Observe the test light for an indication of a fault while completing the following (the lamp will turn on when a fault is detected, indicating MFC circuit short to ground):
    • Shake, wiggle and bend the MFC circuit between the PCM and medium speed FC relay.
    • Lightly tap on the medium speed FC relay to simulate road shock.
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to step 16.
No The problem is intermittent, go to INTERMITTENT PINPOINT TEST .
14 CHECK HIGH SPEED FAN CONTROL (HFC) CIRCUIT FOR OPEN OR SHORT TO POWER
  • Verify A/C and defrost are off.
  • Disconnect the cooling fan connectors.
  • Connect a non-powered test light between the (HIGH) FAN PWR circuit and ground circuit at the cooling fan harness connector.
    • For 2.3L, use driver's side fan.
    • For 3.0L, use passenger's side fan.
  • Key ON, Engine OFF (KOEO).
  • Using the WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select Active Command Modes.
  • Select Output Test Mode.
  • Command high speed fan (using HFC PID) on.
  • Observe the test light for an indication of a fault while completing the following (the lamp will turn off when a fault is detected, indicating an open or short to power):
    • Shake, wiggle and bend the HFC circuit between the PCM and high speed FC relay.
    • Shake, wiggle and bend the VPWR (IGN START/RUN) circuit to the high speed FC relay.
    • Lightly tap on the high speed FC relay to simulate road shock.
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to step 16.
No Go to next step.
15 HFC CIRCUIT FOR SHORT TO GROUND
  • Command high speed fan (using HFC PID) off.
  • Observe the test light for an indication of a fault while completing the following (the lamp will turn on when a fault is detected, indicating HFC circuit short to ground):
    • Shake, wiggle and bend the HFC circuit between the PCM and high speed FC relay.
    • Lightly tap on the medium speed FC relay to simulate road shock.
  • Is a fault indicated? 
 Yes The problem is intermittent, go to INTERMITTENT PINPOINT TEST .
No Replace generator/regulator assembly, see GENERATOR .
16 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Make sure to reconnect all disconnected connectors.
  • Clear DTCs from PCM memory using WDS or equivalent tester generic OBD II function.
  • Perform PCM Quick Test. See PCM QUICK TEST  .
  • Is any DTC present? 
 Yes Replace PCM, see POWERTRAIN CONTROL MODULE (PCM) .
Repeat PCM Quick Test. See PCM QUICK TEST  .
No If any other DTC is present, go to applicable DTC inspection.
If no DTC is present, troubleshooting complete.
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