SFI SYSTEM(w/ Canister Pump Module), Diagnostic DTC:P104A

DTC Code DTC Name
P104A VALVEMATIC SDOWN Circuit

DESCRIPTION

The ECM turns the power supply to the continuously variable valve lift controller assembly on/off. Normally, when the engine switch is on (IG), +B voltage is constantly supplied to the continuously variable valve lift controller assembly. However, when a malfunction is detected in the VALVEMATIC system, the ECM turns the power supply to the continuously variable valve lift controller assembly off. The power supply is turned on/off through the shutdown (SDWN) signal line between the ECM and continuously variable valve lift controller assembly.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P104A VALVEMATIC SDOWN Circuit

Shutdown (SDWN) signal line has a short circuit to +B or ground (1 trip detection logic):


  • Shutdown (SDWN) signal line short circuit to +B: While the engine switch is off, even though the CPU in the ECM requests shutdown (SDWN) signal Lo, the monitor detects Hi

  • Short circuit (Short circuit to ground): While the engine switch is on (IG), even though the CPU in the ECM requests shutdown (SDWN) signal Hi, the monitor detects Lo

  • Short in continuously variable valve lift controller assembly circuit

  • ECM

 Comes on DTC stored

MONITOR DESCRIPTION

When the engine switch is turned on (IG), the ECM turns the shutdown (SDWN) signal on (Hi) which turns the continuously variable valve lift controller assembly power on. Also, when the engine switch is off or during fail-safe mode, the shutdown (SDWN) signal is turned off (Lo) which turns the continuously variable valve lift controller assembly power off.

The ECM electrically monitors if the shutdown (SDWN) signal is actually turned on/off by the output circuit of the CPU. If the power supply to the continuously variable valve lift controller assembly is not turned on/off according to the shutdown (SDWN) signal, the ECM will illuminate the MIL and store this DTC.

MONITOR STRATEGY

Required Sensors/Components

Continuously variable valve lift controller assembly

ECM
Frequency of Operation Continuous

CONFIRMATION DRIVING PATTERN


  1. Connect the GTS to the DLC3.

  2. Start the engine and warm it up.

  3. Turn the GTS on.

  4. Clear the DTCs.

  5. Turn the engine switch off and wait for at least 30 seconds.

  6. Turn the engine switch on (IG) and wait 5 seconds.

  7. Turn the engine switch off and wait for at least 30 seconds.

  8. Turn the engine switch on (IG).

  9. Turn the GTS on.

  10. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

  11. Read the pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  12. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  13. Input the DTC: P104A.

  14. Check the DTC judgment result.

    GTS Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions
    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

WIRING DIAGRAM

B008H5SE09
*a Continuously Variable Valve Lift Controller Assembly

CAUTION / NOTICE / HINT

Note

When one of the following DTCs is output and the MIL is illuminated, actuator position learning is performed during the next trip. After the system returns to normal, actuator position learning is performed during the next trip and the MIL remains illuminated until learning is complete.

Actuator position learning is performed when these DTCs are output.
P1049, P104A, P1055, P2646, P2647, P2648, P2649, P264A, U011B

Tech Tips


  • After performing repairs, perform the confirmation driving pattern and check that DTCs are not output again.

  • Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

  • After using the GTS to perform minimum valve lift learning, keep the engine idling for 30 seconds to complete learning. Otherwise, the VALVEMATIC system may not operate normally, causing poor acceleration, etc.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    5. Read the DTCs.


      Powertrain > Engine and ECT > Trouble Codes
      Result
      Result Proceed to
      DTC P104A is output A
      DTC P1049 is output at same time as DTC P104A B

    B

    GO TO DTC CHART Click here

    A

  2. CHECK HARNESS AND CONNECTOR (CONTINUOUSLY VARIABLE VALVE LIFT CONTROLLER ASSEMBLY - ECM)


    1. Disconnect the continuously variable valve lift controller assembly connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      C62-3 (SDWN) - C65-136 (SDWN) Always Below 1 Ω
      C62-3 (SDWN) or C65-136 (SDWN) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR