DTC P1391:00 [MZR-CD 2.2]

id0102f3149500

DTC P1391:00

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.
Diagnostic support note
•  The MIL does not illuminate.
•  The DTC is stored in the PCM memory.
POSSIBLE CAUSE
•  Melt or burnt glow fuse
•  Glow plug relay connector or terminal malfunction
•  Open circuit in wiring harness between glow plug relay terminal A and battery
•  Open circuit in wiring harness between glow plug relay terminal D and body ground
•  Open circuit in wiring harness between glow plug relay terminal B and PCM terminal 1BT
•  Short to ground circuit in wiring harness between glow plug relay terminal B and PCM terminal 1BT
•  Glow plug relay malfunction
•  Glow plug malfunction
•  PCM connector or terminal malfunction
•  Short to ground circuit in wiring harness between glow plug relay terminal C and PCM terminal 1AU
•  Open circuit in wiring harness between glow plug relay terminal C and PCM terminal 1AU
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA (MODE2) OR SNAPSHOT DATA HAVE BEEN RECORDED
•  Have FREEZE FRAME DATA (mode2) or snapshot data been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA (mode2) and snapshot data on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service 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?
•  Clear the DTC from the PCM memory using the M-MDS.
•  Start the engine.
•  Perform the KOEO self test.
•  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 2.2].)
4
INSPECT GLOW FUSE
•  Switch the ignition to off.
•  Inspect the glow fuse.
•  Is there any malfunction?
Yes
Replace the glow fuse, then go to Step 15.
No
Go to the next step.
5
INSPECT GLOW PLUG RELAY CONNECTOR FOR POOR CONNECTION
•  Switch the ignition to 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 Step 15.
No
Go to the next step.
6
INSPECT GLOW PLUG RELAY POWER SUPPLY FOR OPEN CIRCUIT
•  Switch the ignition to off.
•  Measure the voltage between glow plug relay terminal A 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 15.
7
INSPECT GLOW PLUG RELAY GROUND FOR OPEN CIRCUIT
•  Switch the ignition to off.
•  Remove the glow plug relay.
•  Inspect for continuity between glow plug relay terminal D 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 15.
8
INSPECT GLOW PLUG RELAY SIGNAL FOR OPEN CIRCUIT
•  Switch the ignition to ON (Engine off).
•  Measure the voltage between glow plug relay terminal B.
•  Is voltage less than 0.25 V?
Yes
Repair or replace the wiring harness for an open circuit, go to Step 15.
No
Go to the next step.
9
INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR SHORT TO GROUND
•  Switch the ignition to off.
•  Inspect for continuity between glow plug relay terminal B and body ground.
•  Is there continuity?
Yes
If the short to ground circuit could be detected:
•  Repair or replace the wiring harness for a possible short to ground.
If the short to ground circuit could not be detected:
•  Replace the PCM (short to ground in the PCM internal circuit).
Go to Step 15.
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 15.
11
INSPECT GLOW PLUG
•  Inspect the glow plug.
•  Is there any malfunction?
Yes
Replace the glow plug, then go to Step 15.
(See GLOW PLUG REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Go to the next step.
12
INSPECT POOR CONNECTION OF PCM CONNECTOR
•  Switch the ignition to 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 15.
No
Go to the next step.
13
INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR SHORT TO GROUND
•  Switch the ignition to off.
•  Remove the glow plug connector.
•  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, then go to Step 15.
No
Go to the next step
14
INSPECT GLOW PLUG RELAY SIGNAL CIRCUIT FOR OPEN CIRCUIT
•  Switch the ignition to off.
•  Inspect for continuity between glow plug relay terminal C and PCM terminal 1AU.
•  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.
15
VERIFY TROUBLESHOOTING OF DTC P1391:00 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Start the engine.
•  Perform the KOEO self test.
•  Is the same DTC present?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the PCM.
Go to the next step.
No
Go to the next step.
16
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR-CD 2.2].)
No
DTC troubleshooting completed.