| Mazda P1391 | Glow plug circuit low input |
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DETECTION CONDITION
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• The PCM monitors the glow plug relay signal. If the voltage at PCM terminal 210 remains low, the PCM determines that there is a glow plug relay circuit malfunction.
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POSSIBLE CAUSE
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• Glow plug relay malfunction
• Melt or burnt glow fuse
• PCM malfunction
• Connector or terminal malfunction
• Open circuit in the wiring harness between glow plug relay terminal A and glow fuse
• Open circuit in the wiring harness between glow plug relay terminal D and PCM terminal 132
• Short to ground in the wiring harness between glow plug relay terminal D and PCM terminal 132
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Diagnostic procedure
| STEP | INSPECTION | ACTION | |
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1
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VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has the FREEZE FRAME DATA been recorded?
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Yes
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Go to the next step.
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No
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Record the FREEZE FRAME DATA on the repair order, then go to the next step.
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2
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VERIFY RELATED REPAIR INFORMATION AVAILABILITY
• Verify related service repair information availability.
• Is any related repair information available?
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Yes
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Perform repair or diagnosis according to the available repair information.
• If the vehicle is not repaired, go to the next step.
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No
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Go to the next step.
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3
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VERIFY CURRENT SIGNAL STATUS: IS CONCERN INTERMITTENT OR CONSTANT?
• Connect the M-MDS to the DLC-2.
• Clear the DTC from the PCM memory using the M-MDS.
• Run the vehicle under the FREEZE FRAME DATA stored condition.
• Is the same DTC present?
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Yes
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Go to the next step.
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No
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Intermittent concern exists.
Perform the “INTERMITTENT CONCERNS TROUBLESHOOTING”.
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4
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INSPECT FUSE CONDITION
• Turn the engine switch off.
• Verify the glow fuse conditions.
• Is there any melt or burnt?
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Yes
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Go to the symptom troubleshooting NO.1 MELTING OF MAIN OR OTHER FUSES.
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No
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Go to the next step.
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5
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INSPECT GLOW PLUG RELAY CONNECTOR FOR POOR CONNECTION
• Turn the engine switch off.
• Disconnect the glow plug relay connector.
• Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
• Is there any malfunction?
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Yes
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Repair or replace the terminal, then go to Step 11.
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No
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Go to the next step.
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6
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INSPECT GLOW PLUG RELAY POWER SUPPLY FOR OPEN CIRCUIT
• Turn the engine switch on.
• Disconnect the PCM connector.
• Measure the voltage between glow plug relay terminal A and body ground.
• Measure the voltage between glow plug relay terminal B and body ground.
• Is the voltage B+?
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Yes
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Go to the next step.
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No
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Repair or replace the wiring harness for an open circuit, then go to Step 11.
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7
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INSPECT GLOW PLUG RELAY
• Inspect the glow plug relay.
• Is there any malfunction?
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Yes
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Go to the next step.
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No
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Replace the glow plug relay, then go to Step 11.
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8
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INSPECT PCM CONNECTOR FOR POOR CONNECTION
• Turn the engine switch off.
• Disconnect the PCM connector.
• Inspect for poor connection (such as damaged/pulled-out terminals, corrosion).
• Is there any malfunction?
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Yes
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Repair or replace the suspected terminal, then go to Step 11.
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No
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Go to the next step.
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9
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INSPECT GLOW PLUG RELAY CONTROL CIRCUIT FOR SHORT TO GROUND
• Turn the engine switch off.
• Disconnect the PCM connector.
• Inspect for continuity between glow plug relay terminal D and body ground.
• Is there continuity?
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Yes
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Repair or replace the wiring harness for a short to ground, then go to Step 11.
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No
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Go to the next step.
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10
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INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR OPEN CIRCUIT
• Turn the engine switch off.
• Disconnect the PCM connector.
• Inspect for continuity between glow plug relay terminal D and PCM terminal 132.
• Is there continuity?
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Yes
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Go to the next step
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No
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Repair or replace the wiring harness for an open circuit, then go to the next step.
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11
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VERIFY THAT DTC P1391 TROUBLESHOOTING IS COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear DTC from PCM memory using M-MDS.
• Run the vehicle under the FREEZE FRAME DATA stored condition.
• Is the same DTC present?
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Yes
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Replace the PCM, then go to the next step.
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No
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Go to the next step.
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12
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VERIFY AFTER REPAIR PROCEDURE
• Perform the after repair procedure.
• Are any DTCs present?
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Yes
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Go to the applicable DTC inspection.
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No
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DTC troubleshooting completed.
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