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HOMESERVICE MANUALSMAZDA2006B4000 BASE, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE SYMPTOM TROUBLESHOOTING - (3 OF 5)DTC APPLICATION CHART - POWERTRAIN CONTROL MODULE (PCM)COOLING FAN MALFUNCTION (2.3L)
2006 Mazda B4000 Base, Automatic

Cooling Fan Malfunction (2.3L)

2006 Mazda B4000 Base, AutomaticSECTION Cooling Fan Malfunction (2.3L)
DTC P1474 DETECTION CONDITION & POSSIBLE CAUSES

DTC P1474 COOLING FAN MALFUNCTION (2.3L)
DETECTION CONDITION 
  • P1474 indicates excessive current draw is detected on the fan control (FC) circuit when the powertrain control module (PCM) grounds the circuit or with the FC circuit not grounded by the PCM, voltage is not detected on the FC circuit (the PCM expects to detect VPWR voltage coming through the low speed FC relay coil to the FC circuit).
POSSIBLE CAUSE 
  • Open or shorted LFC circuit
  • Open VPWR or IGN START/RUN circuit to FC relay
  • Damaged FC relay
  • Damaged PCM
HINT  Engine Cooling Fan Control Description 
  • The PCM monitors certain parameters such as engine coolant temperature, vehicle speed, A/C on/off status, and A/C pressure to determine engine cooling fan needs.
  • The PCM controls the fan operation through the FC outputs.
G04306987Courtesy of MAZDA MOTORS CORP.
DTC P1474 DIAGNOSTIC PROCEDURE

DTC P1474 COOLING FAN MALFUNCTION (2.3L)
STEP INSPECTION ACTION
1
  • Was the PCM quick test performed?
 Yes For continuous memory DTC P1474 Go to step 7.
For all others, Go to next step.
No Perform PCM quick test. See PCM QUICK TEST  .
2 CHECK VPWR VOLTAGE TO FAN RELAY
  • Disconnect fan control relay.
  • Key on, engine off (KOEO).
  • Measure VPWR circuit voltage at the fan control relay harness connector.
  • Is voltage greater than 10.5 volts? 
 Yes Go to next step.
No Repair open VPWR circuit to the fan control relay.
Go to step 9.
3 CHECK FOR FC CIRCUIT CYCLING
  • Connect a non-powered test light between the VPWR circuit and the FC circuit at the fan control relay harness connector.
  • While observing the test light, turn the climate control selector switch from OFF to DEFROST several times.
  • Does the test light turn on and off? 
 Yes Replace fan control relay.
Go to step 9.
No Repeat test step to verify results. If results are still the same, remove test light. Key OFF.
Go to next step.
4 CHECK FC CIRCUIT FOR SHORT TO POWER IN HARNESS
  • Disconnect PCM.
  • Key on, engine off (KOEO).
  • Measure voltage between the FC circuit at the 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 9.
5 CHECK FC CIRCUIT FOR SHORT TO GROUND IN HARNESS
  • Key OFF.
  • Disconnect WDS or equivalent tester.
  • Measure resistance between the FC
  • circuit at the 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 9.
6 CHECK FOR OPEN FC CIRCUIT
  • Install breakout box and leave PCM disconnected.
  • Measure resistance of FC circuit between PCM test pin 45 and the fan control relay harness connector.
  • Is resistance less than 5.0 ohms? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Go to step 9.
No Repair open circuit.
Go to step 9.
7 CHECK FAN CONTROL (FC) CIRCUIT FOR OPEN OR SHORT TO POWER
  • Verify A/C and defrost are off.
  • Disconnect the cooling fan connector.
  • Connect a non-powered test light between the VPWR circuit and ground at the cooling fan harness connector.
  • Key on, engine off (KOEO).
  • Turn the climate control selector switch from OFF to DEFROST.
  • 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 FC circuit between the PCM and FC relay
    • Shake,-wiggle and bend the VPWR circuit to the FC relay
    • Lightly tap on the FC relay to simulate road shock
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to step 9.
No Go to next step.
8 CHECK FC CIRCUIT FOR SHORT TO GROUND
  • Turn the climate control selector switch from DEFROST to 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 FC circuit short to ground):
    • Shake, wiggle and bend the FC circuit between the PCM and FC relay
    • Lightly tap on the FC relay to simulate road shock
  • Is a fault indicated? 
 Yes Isolate fault and repair.
Go to next step.
No The problem is intermittent.
See GENERAL PINPOINT TEST 4: INTERMITTENT .
9 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Connect all disconnected connectors.
  • Clear DTCs from PCM memory using WDS or equivalent tester.
  • Perform PCM quick test.
  • Is same DTC present? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Repeat PCM quick test.
No If any other DTC is present, go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) . If no DTC is present, troubleshooting is complete.
RENDER: 1.0x

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