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 plug relay voltage is 0.25 V or less when the glow plug relay is operating, the PCM determines that there is a malfunction in the glow plug relay circuit.
Diagnostic support note
•  The MIL does not illuminate.
•  FREEZE FRAME DATA (Mode 2)/Snapshot data is not available.
•  The DTC is not stored in the PCM memory.
POSSIBLE CAUSE
•  Glow plug relay malfunction
•  Open circuit in wiring harness between glow plug relay terminal B and body ground
•  Short to ground or open circuit in wiring harness between battery and glow plug relay
―  Short to ground in wiring harness between battery positive terminal and glow plug relay terminal A
―  Open circuit in wiring harness between battery positive terminal and glow plug relay terminal A
•  Short to ground or open circuit in wiring harness between glow plug relay and PCM
―  Short to ground in wiring harness between glow plug relay terminal C and PCM terminal 1AU
―  GLOW 40 A fuse malfunction
―  GLOW SIG 5 A fuse malfunction
―  Open circuit in wiring harness between glow plug relay terminal C and PCM terminal 1AU
•  Glow plug connector or terminals malfunction
•  Glow plug malfunction
•  Short to ground in wiring harness between glow plug relay terminal D and PCM terminal 1BT
•  PCM connector or terminals malfunction
•  Open circuit in wiring harness between glow plug relay terminal D and PCM terminal 1BT
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
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.
2
VERIFY CURRENT INPUT 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” procedure.
3
INSPECT GLOW PLUG RELAY
•  Switch the ignition to off.
•  Remove the glow plug relay.
•  Inspect the glow plug relay.
•  Is there any malfunction?
Yes
Replace the glow plug relay, then go to Step 12.
No
Go to the next step.
4
INSPECT GLOW PLUG RELAY CIRCUIT FOR OPEN CIRCUIT
•  Glow plug relay is removed.
•  Inspect for continuity between glow plug relay terminal B (wiring harness-side) and body ground.
•  Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness for a possible open circuit, then go to Step 12.
5
INSPECT GLOW PLUG RELAY POWER SUPPLY CIRCUIT FOR SHORT TO GROUND OR OPEN CIRCUIT
•  Glow plug relay is removed.
•  Measure the voltage at the glow plug relay terminal A (wiring harness-side).
•  Is the voltage B+?
Yes
Reinstall the glow plug relay, then go to the next step.
No
Repair or replace the wiring harness for a possible short to ground or open circuit, then go to Step 12.
6
INSPECT PCM POWER SUPPLY CIRCUIT FOR SHORT TO GROUND OR OPEN CIRCUIT
•  Switch the ignition to ON (engine off).
•  Measure the voltage at the PCM terminal 1AU (wiring harness-side).
•  Is the voltage B+?
Yes
Go to the next step.
No
Inspect the GLOW 40 A fuse and GLOW SIG 5 A fuse.
•  If the fuse is melt:
―  Repair or replace the wiring harness for a possible short to ground.
―  Replace the malfunctioning fuse.
•  If the fuse is deterioration:
―  Replace the malfunctioning fuse.
•  If all fuses are normal:
―  Repair or replace the wiring harness for a possible open circuit.
Go to Step 12.
7
INSPECT GLOW PLUG CONNECTOR CONDITION
•  Switch the ignition to off.
•  Disconnect the glow plug connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector and/or terminals, then go to Step 12.
No
Go to the next step.
8
INSPECT GLOW PLUG
•  Inspect the glow plug.
•  Is there any malfunction?
Yes
Replace the glow plug, then go to Step 12.
(See GLOW PLUG REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Go to the next step.
9
INSPECT GLOW PLUG RELAY CIRCUIT FOR SHORT TO GROUND
•  Glow plug connector is disconnected.
•  Remove the glow plug relay.
•  Inspect for continuity between glow plug relay terminal D (wiring harness-side) 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 12.
No
Go to the next step.
10
INSPECT PCM CONNECTOR CONDITION
•  Disconnect the PCM connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector and/or terminals, then go to Step 12.
No
Go to the next step.
11
INSPECT GLOW PLUG RELAY CIRCUIT FOR OPEN CIRCUIT
•  Glow plug and PCM connectors are disconnected.
•  Glow plug relay is removed.
•  Inspect for continuity between glow plug relay terminal D (wiring harness-side) and PCM terminal 1BT (wiring harness-side).
•  Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness for a possible open circuit, then go to the next step.
12
VERIFY DTC TROUBLESHOOTING 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
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Go to the next step.
13
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.