DTC P1312 [WL-3]

id0102b8957000

DTC P1312

TCV circuit malfunction
DETECTION CONDITION
•  The PCM monitors the difference in voltage between the target injection timing and the actual injection timing while the ECT is above 80°C {176°F} and the engine is running. If the difference in voltage is above the threshold for 12.75 s, the PCM determines that the injection timing control system is malfunctioning.
POSSIBLE CAUSE
•  Connector or terminal malfunction
•  Open circuit in wiring harness between fuel injection pump connector A terminal C and main relay terminal D
•  Short to ground in wiring harness between fuel injection pump connector A terminal B and PCM terminal 4U
•  Open circuit in wiring harness between fuel injection pump connector A terminal B and PCM terminal 4U
•  TCV malfunction
•  Fuel injection pump (injection timing control) malfunction
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
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.
2
VERIFY CURRENT SIGNAL STATUS: IS CONCERN INTERMITTENT OR CONSTANT?
•  Clear the DTC.
•  Start the engine.
•  Access the ECT PID using the M-MDS.
•  Wait until the ECT PID is above 80°C {176°F}.
•  Is the same DTC present?
Yes
Go to the next step.
No
Intermittent concern exists.
Perform the “INTERMITTENT CONCERN TROUBLESHOOTING”.
(See INTERMITTENT CONCERN TROUBLESHOOTING [WL-3].)
3
VERIFY OTHER DTC IS PRESENT
•  Are there other DTCs present?
Yes
Perform the appropriate DTC troubleshooting procedure.
(See DTC TABLE [WL-3].)
then go to Step 8.
No
Go to the next step.
4
INSPECT FUEL INJECTION PUMP CONNECTOR FOR POOR CONNECTION
•  Turn the engine switch to the off position.
•  Disconnect fuel injection pump connector A.
•  Check for poor connection (damaged, pulled-out pins, corrosion, etc.).
•  Is there a malfunction?
Yes
Repair or replace the terminal, then go to Step 9.
No
Go to the next step.
5
INSPECT TCV POWER CIRCUIT
•  Turn the engine switch to the ON position (Engine off).
•  Measure the voltage between fuel injection pump connector A terminal C (wiring harness-side) and body ground.
•  Is the voltage B+?
Yes
Go to the next step.
No
Repair or replace the TCV power circuit for an open circuit, then go to Step 9.
6
INSPECT TCV CONTROL CIRCUIT FOR SHORT TO GROUND
•  Turn the engine switch to the off position.
•  Check for continuity between fuel injection pump connector A terminal B (wiring harness-side) and body ground.
•  Is there continuity?
Yes
Repair or replace the TCV control circuit for a short to ground, then go to Step 9.
No
Go to the next step.
7
INSPECT PCM CONNECTOR POOR FOR CONNECTION
•  Disconnect the PCM connector.
•  Check for poor connection (damaged, pulled-out pins, corrosion, etc.).
•  Is there a malfunction?
Yes
Repair or replace the terminal, then go to Step 9.
No
Go to the next step.
8
INSPECT TCV CONTROL CIRCUIT FOR OPEN CIRCUIT
•  Check for continuity between fuel injection pump connector A terminal B (wiring harness-side) and PCM terminal 4U (wiring harness-side).
•  Is there continuity?
Yes
The fuel injection pump may have a malfunction. Consult your distributor for the inspection of the fuel injection pump.
Go to the next step.
No
Repair or replace the TCV control circuit for an open circuit, then go to the next step.
9
INSPECT TCV
•  Perform the TCV Inspection.
•  Is the TCV normal?
Yes
The fuel injection pump may have a mechanical malfunction. Consult your distributor for the inspection of the fuel injection pump.
Then go to the next step.
No
Consult your distributor for the replacement of the TCV.
Then go to the next step.
10
VERIFY TROUBLESHOOTING OF DTC P1312 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Turn the engine switch to the ON position (Engine off).
•  Clear the DTCs from the PCM memory using the M-MDS.
•  Start the engine.
•  Access the ECT PID using the M-MDS.
•  Wait until the ECT PID is above 80°C {176°F}.
•  Is the same DTC present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
11
VERIFY AFTER REPAIR PROCEDURE
•  Perform “AFTER REPAIR PROCEDURE”.
•  Is there any DTC present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [WL-3].)
No
Troubleshooting completed.