DTC P1391 [MZR-CD (RF Turbo)]

id0102f1837100

DTC P1391

Glow plug circuit low input
DETECTION CONDITION
•  The PCM monitors the output signal to the glow plug relay when the glow relay is on. If the glow relay voltage is 0.25 V or less when the glow relay is operating, The PCM determines that there is a malfunction in the glow relay circuit.
POSSIBLE CAUSE
•  Glow plug relay malfunction
•  Melt or burnt glow fuse
•  PCM malfunction
•  Glow plug malfunction
•  Connector or terminal malfunction
•  Open circuit in wiring harness between glow plug relay terminal A and PCM terminal 75
•  Open circuit in wiring harness between glow plug relay terminal C and PCM terminal 37
•  Open circuit in wiring harness between glow plug relay terminal B and body ground
•  Open circuit in wiring harness between glow plug relay terminal D and GLOW FUSE
•  Short to ground circuit in wiring harness between glow plug relay terminal A and PCM terminal 75
•  Short to ground circuit in wiring harness between glow plug relay terminal C and PCM terminal 37

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
•  Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED REPAIR INFORMATION AVAILABILITY
•  Verify related service repair information availability.
•  Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
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.
•  Start the engine.
•  Is the same DTC present?
Yes
Go to the next step.
No
Intermittent concern exists.
Perform the “INTERMITTENT CONCERN TROUBLESHOOTING”.
(See INTERMITTENT CONCERN TROUBLESHOOTING [MZR-CD (RF Turbo)].)
4
FUEL INJECTOR CONNECTOR FOR POOR CONNECTION
•  Turn the engine switch to the ON position.
•  Inspect for poor connection (such as damaged/pulled- out terminals, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the terminal, then go to Step 14.
No
Go to the next step.
5
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?
Yes
Repair or replace the terminal, then go to the next step.
No
Go to the next step.
6
INSPECT GLOW PLUG RELAY POWER SUPPLY FOR OPEN CIRCUIT
•  Turn the engine switch off.
•  Measure the voltage between glow plug relay terminal D and body ground.
•  Is the voltage B+?
Yes
Go to the next step.
No
Repair or replace the wiring harness for an open circuit, go to Step 14.
7
INSPECT GLOW PLUG RELAY GROUND FOR OPEN CIRCUIT
•  Turn the engine switch off.
•  Remove the glow plug relay.
•  Inspect for continuity between glow plug relay terminal B and ground.
•  Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness for an open circuit, go to Step 14.
8
INSPECT GLOW PLUG RELAY SIGNAL FOR OPEN CIRCUIT
•  Turn the engine switch to the ON position (Engine off).
•  Measure the voltage between glow plug relay terminal C.
•  Is voltage less than 0.25 V?
Yes
Repair or replace the wiring harness for an open circuit, go to Step 14.
No
Go to the next step.
9
INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR SHORT TO GROUND
•  Turn the engine switch off.
•  Inspect for continuity between glow plug relay terminal C and body ground.
•  Is there continuity?
Yes
Repair or replace the wiring harness for a short to ground, go to Step 14.
No
Go to the next step.
10
INSPECT GLOW PLUG RELAY
•  Inspect the glow plug relay.
•  Is there any malfunction?
Yes
Go to the next step.
No
Replace the glow plug relay, go to Step 14.
11
INSPECT POOR CONNECTION OF PCM CONNECTOR
•  Turn the engine switch off.
•  Inspect for poor connection (such as damaged/pulled-out terminals, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the suspected terminal, go to Step 14.
No
Go to the next step.
12
INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR SHORT TO GROUND
•  Turn the engine switch off.
•  Remove the glow plug connector.
•  Inspect for continuity between glow plug relay terminal A and body ground.
•  Is there continuity?
Yes
Repair or replace the wiring harness for a short to ground, then go to Step 14.
No
Go to the next step
13
INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR OPEN CIRCUIT
•  Turn the engine switch off.
•  Inspect for continuity between glow plug relay terminal A and PCM terminal 75.
•  Is there continuity?
Yes
Go to the next step
No
Repair or replace the wiring harness for an open circuit, then go to the next step.
14
VERIFY TROUBLESHOOTING OF DTC P1391 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Start the engine.
•  Is the same DTC present?
Yes
Replace the PCM, go to the next step.
(See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)
No
Go to the next step.
15
VERIFY AFTER REPAIR PROCEDURE
•  Perform the Repair Verification Drive Mode.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR-CD (RF Turbo)].)
No
Troubleshooting completed.