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Pcm Relay

DTC DETECTION CONDITION POSSIBLE COUSES CHART

DTC P0685, P0689, P0690 PCM RELAY
DETECTION CONDITION
  • P0685 indicates the PCM power relay circuit open.
  • P0689 indicates the PCM power relay sense circuit low.
  • P0690 indicates the PCM power relay sense circuit high.
POSSIBLE CAUSES
  • Harness circuits open or short to ground.
  • Damaged PCM power relay.
  • PCM failure.
HINT PCM Power Relay Description 
  • Provides power source for PCM.
G05463680Courtesy of MAZDA MOTORS CORP.
G05463681Courtesy of MAZDA MOTORS CORP.
DTC DETECTION CONDITION POSSIBLE COUSES CHART

STEP INSPECTION ACTION
1 PCM QUICK TEST
  • Was PCM Quick Test carried out? 
 Yes GO to the next step.
No CARRY OUT the PCM Quick Test. See PCM QUICK TEST  .
2 CHECK FOR DTCs
  • Are DTCs P0685, P0685 and P0690 present? 
 Yes For DTCs P0685 and P0690, GO to step 6.
For DTC P0689, GO to step 9.
Key OFF.
No GO to the next step.
3 CHECK B+ AND IGN START/RUN VOLTAGE TO PCM POWER RELAY
  • Key OFF.
  • Disconnect PCM power relay connector.
  • Measure B+ circuit (B/Y) voltage at the PCM power relay connector.
  • Key ON, engine OFF (KOEO).
  • Measure IGN START/RUN circuit (W/V) voltage at PCM power relay connector.
  • Are both voltages greater than 10.5 volts? 
 Yes Key OFF. GO to the next step.
No Key OFF.
REPAIR open in B+ (B/Y) or IGN START/RUN (W/V) circuit, VERIFY condition of PCM diode.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
4 CHECK GROUND CIRCUIT TO POWER RELAY
  • Measure voltage between B+ (B/Y) circuit and ground (B) circuit at PCM power relay connector.
  • Key OFF.
  • Is the voltage greater than 10.5 volts? 
 Yes INSTALL a new PCM power relay.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
No REPAIR open ground circuit.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
5 CHECK FOR AN OPEN VPWR CIRCUIT BETWEEN THE PCM AND POWER RELAY
  • Disconnect PCM.
  • Measure the resistance between VPWR circuit (W/R) between IAC valve connector 0140-116 and PCM relay connector.
  • Is the resistance less than 5.0 ohms? 
 Yes INSTALL a new PCM power relay.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
No REPAIR the open circuit.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
6 DTCs P0685 OR P0690: CHECK THE PCMRC CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS
  • Measure the resistance between PCMRC pin, harness side and ground.
  • Is the resistance greater than 10K ohms? 
 Yes GO to the next step.
No REPAIR short circuit to ground.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
7 CHECK THE PCMRC CIRCUIT THE ISP-R CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS
  • Measure the voltage between ISP-R pin, harness side and ground.
  • Is any voltage present? 
 Yes REPAIR short circuit to voltage.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
No GO to the next step.
8 CHECK THE INJPWRM CIRCUIT FOR AN OPEN IN THE HARNESS
  • Disconnect INJ connector.
  • Measure the resistance between INJPWRM pin, harness side VPWR pin, harness side.
  • Is the resistance less than 5.0 ohms? 
 Yes GO to the next step.
No REPAIR the open circuit.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
9 DTC P0689: CHECK THE ISP-R VOLTAGE AT THE PCM HARNESS CONNECTOR
  • Disconnect PCM connector.
  • Key on, engine off. (KOEO)
  • Measure the resistance between ISP-R pin, harness side and ground.
  • Is the voltage greater than 10.5 volts? 
 Yes GO to the next step.
No REPAIR the open circuit.
RESTORE the vehicle.
REPEAT the PCM Quick Test.
See PCM QUICK TEST  .
10 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Disconnect all the PCM connectors.
  • Check for:
    • corrosion
    • damaged pins
    • pushed-out pins
  • Connect all connectors and make sure they seat correctly.
  • Clear DTCs from PCM memory using IDS or equivalent tester generic OBD II tester.
  • Carry out the PCM Quick Test. See PCM QUICK TEST  .
  • Is the same DTC present? 
 Yes INSTALL a new PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL/INSTALLATION - 2.5L or POWERTRAIN CONTROL MODULE (PCM) REMOVAL/INSTALLATION - 3.0L .
REPEAT the 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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