FC CONTROL SYSTEM, Diagnostic DTC:P1D91-450

DTC Code DTC Name
P1D91-450 Air Control System Performance

DESCRIPTION

The air system of the FC system feeds the FC stack with oxygen, so that the FC stack can generate power. It consists of the FC air compressor with motor assembly (for feeding air), the air pressure regulating value and air shunt valve (for regulating FC stack air pressure), the sensors for air pressure, temperature and airflow rate (for monitoring the control condition), and the pipes, intercooler, etc.

If the FC control ECU detects that the actual air pressure measured by the pressure sensor has significantly deviated from an estimated air pressure based on the air compressor motor speed, air shunt valve position, and air pressure regulating valve position, it will interpret that there is something wrong with somewhere in the air system components including the air pipes, and set this DTC.

For the circuit diagram, refer to DTC P0101-450.

Click here

DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate
P1D91-450 Air Control System Performance

If an FC stack inlet air pressure abnormally increases during regenerative braking (this is interpreted that the air shunt valve is not operating)

(1 trip detection logic)

  • FC stack assembly (air shunt valve)

  • Air system pipes

 Master Warning Light: Comes on

Tech Tips

During deceleration, the motor speed of the FC air compressor is forced to increase so as to achieve braking effect (regenerative braking). At this time, the air shunt valve is actuated to force some of the air that flows into the FC stack to flow into the exhaust side. Despite that, if the shunt valve does not operate due to malfunctions, and it results in an excessive increase in the "Smoothed Value of the FC Stack Air Pressure (FC Stack Inlet)", the FC control ECU sets the DTC.

Detection timing
Vehicle Condition

FC shutdown

(power switch on (IG))

 FC startup process FC intermittent operation

FC is generating power

(vehicle is in stationary)

FC is generating power

(vehicle is traveling)

 FC shutdown process

Data List

"FC Mode"

 FC Shutdown FC Startup Process FC Working FC Shutdown Process

Data List

"FC Intermittent Operation"

 OFF ON OFF OFF
DTC Detection - - - - ○ -

Tech Tips

By accessing the "FC Mode" and "FC Intermittent Operation" in the freeze frame data, the FC system condition at the time the malfunction occurred can be checked.

Related Data List
DTC No. Data List
P1D91-450 Smoothed Value of FC Stack Air Pressure (FC Stack Inlet)

The following items can be helpful when performing repairs:



Related Utility
DTC No. Utility
P1D91-450 Check Mode (Air System Component Inspection)

Note

As the airflow volume will be decreased at areas of high elevation, the check mode (air system component inspection) judgment result will not be accurate. For this reason, check mode (air system component inspection) judgment should be performed at elevations below 1000 m (3280 ft.). If a DTC is output, use the pressure waveform data during testing to evaluate the results.

Tech Tips

By entering check mode, abnormalities in the air shunt valve, air pressure regulating valve or air system lines can be found.

CAUTION / NOTICE / HINT

Note


  • When air system components have been replaced, enter the Utility "Check Mode (Air System Component Inspection)" and check that one of the following conditions is met.

    Click here


    1. No DTC output.

    2. DTC P1D91-450 has been output, but the pressure waveform data during testing is normal.

  • Primarily, presence of this DTC may be a sign of air shunt valve malfunctions.

  • When the vehicle is parked with the power switch off, if the FC control ECU judges that the FC stack temperature will go below 0°C (32°F), it activates the FC air compressor, hydrogen pump and FC cooling water pump for a maximum of 180 seconds and drains water from the FC stack assembly. When performing inspection or repairs with the power switch off (not on (IG) or on (READY)), disconnect the cable from the negative (-) auxiliary battery terminal before performing work (If the auxiliary battery voltage is needed to conduct inspection, warm up the FC system beforehand).

Tech Tips

After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. Drive the vehicle for 10 minutes according to the freeze frame data (Vehicle Speed, Accelerator Degree, etc.).

    If vehicle speeds, accelerator pedal positions, road conditions, ambient temperatures and climates at the time the malfunction occurred can be determined, take them into account. Because DTC detection is performed during deceleration (regenerative braking), drive the vehicle in a way so that regenerative braking is performed.

    CAUTION:

    Perform this road test only in an appropriate safe location, in accordance with all local laws.

PROCEDURE


  1. CHECK DTC OUTPUT

    Note

    The freeze frame data is cleared when DTCs are cleared. Be sure to make a note of necessary data in advance.


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / FC / Trouble Codes.

    5. Check for DTCs.


      Powertrain > FC > Trouble Codes
      Result
      Result Proceed to
      P1D91-450 only is output, or DTCs except the ones in the table below are also output. A
      Any of the following DTCs are also output. B
      Malfunction Content Relevant DTC
      Sensor and Actuator Circuit Malfunction P1E22-450 Air Pressure Regulating Valve Phase A Circuit Low
      P1E23-450 Air Pressure Regulating Valve Phase A Circuit High
      P1E27-450 Air Pressure Regulating Valve Phase B Circuit Low
      P1E28-450 Air Pressure Regulating Valve Phase B Circuit High
      P1E2C-450 Air Shunt Valve Phase A Circuit Low
      P1E2D-450 Air Shunt Valve Phase A Circuit High
      P1E32-450 Air Shunt Valve Phase B Circuit Low
      P1E33-450 Air Shunt Valve Phase B Circuit High

      Tech Tips

      DTC P1D91-450 may be set due to problems that cause the DTCs shown above to be output. If such happens, troubleshoot the suspected area(s) corresponding to the output DTC(s) in order starting with the listed DTCs shown in the table above.

    6. Turn the power switch off.


    B

    GO TO DTC CHART Click here

    A

  2. CHECK AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY


    1. Check that the air cleaner filter element sub-assembly is not clogged.

      OK
      The air cleaner filter element sub-assembly is not clogged
      Result
      Proceed to
      OK
      NG

    OK

    GO TO STEP 4 Click here

    NG

  3. CLEAN OR REPLACE AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY


    1. Clean or replace the air cleaner filter element sub-assembly.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  4. CHECK INTAKE AND EXHAUST PIPING


    1. Check that no air comes in without flowing through each part of the intake air system and the exhaust drainage pipe is not clogged, disconnected, or damaged.

      OK
      The intake and exhaust piping is not clogged, disconnected or damaged
      Result
      Proceed to
      OK
      NG

    OK

    GO TO STEP 6 Click here

    NG

  5. REPAIR OR REPLACE MALFUNCTIONING PARTS

    Result
    Proceed to
    NEXT

    NEXT

  6. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / FC / Trouble Codes.

    5. Clear the DTCs.


      Powertrain > FC > Clear DTCs

    6. Turn the power switch off and wait for 3 minutes or more.

      Result
      Proceed to
      NEXT

    NEXT

  7. SELECT CHECK MODE (CHECK MODE (AIR SYSTEM COMPONENT INSPECTION))

    Note


    • As the airflow volume will be decreased at areas of high elevation, the check mode (air system component inspection) judgment result will not be accurate. For this reason, check mode (air system component inspection) judgment should be performed at elevations below 1000 m (3280 ft.). If a DTC is output, use the pressure waveform data during testing to evaluate the results.

    • Conduct air system component inspection when "Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)" in the Data List is over 10°C (50°F).


    1. Move the shift lever to P.

    2. Connect the GTS to the DLC3.

    3. Turn the power switch on (IG).

    4. Turn the GTS on.

    5. Enter the following menus: Powertrain / FC / Utility / Check Mode.


      Powertrain > FC > Utility
      Tester Display
      Check Mode

      Note


      • When changing between modes, the stored DTC and freeze frame data is erased, so save the detected data before changing modes.

      • Changing from normal mode to check mode function is not available when the power switch is turned on (READY).

    6. Enter the following menus: Powertrain / FC / Data List / Smoothed Value of FC Stack Air Pressure (FC Stack Inlet), Target Air Pressure Regulating Valve Position, Target Air Shunt Valve Position, Air Compressor Revolution


      Powertrain > FC > Data List
      Tester Display
      Smoothed Value of FC Stack Air Pressure (FC Stack Inlet)
      Target Air Pressure Regulating Valve Position
      Target Air Shunt Valve Position
      Air Compressor Revolution

    7. During check mode (air system component inspection), use the Snapshot function of the GTS to record the values of the Data List items listed above.

    8. Turn the power switch on (READY).

      Note

      The following conditions must be met for the Air System Component Inspection. If any one of the conditions is not met during inspection, the ongoing inspection will be canceled, and it will restart from the beginning when all conditions are satisfied again.


      • Shift lever in P

      • Power switch on (READY)

      • Air system component inspection is not yet completed

    9. Wait for 5 minutes.

      Note

      A GTS shows no indication that air system component inspection has finished.

    10. Enter the following menus: Powertrain / FC / Trouble Codes.

    11. Check for DTCs.


      Powertrain > FC > Trouble Codes

      Note

      If an abnormality is found during Check Mode, DTC P1D91-450 will be set.

      Result
      Result Proceed to
      DTC P1D91-450 is output A
      DTCs are not output B

    B

    SIMULATION TEST Click here

    A

  8. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Check the data obtained during Check Mode (Air System Component Inspection), which was recorded with the snapshot.

      Figure 1. Reference waveforms of the Data List values in check mode (air system component inspection)

      B000ZJ2E10
      Result
      Result Proceed to
      Variation (B) of the "Smoothed Value of FC Stack Air Pressure (FC Stack Inlet)" value in the air shunt valve inspection section is less than 5 kPa (elevation 1000 m (3280 ft.) or less)*1 A
      Variation (A) of the "Smoothed Value of FC Stack Air Pressure (FC Stack Inlet)" value in the air pressure regulating valve inspection section is less than 5 kPa (elevation 1000 m (3280 ft.) or less)*2 B
      Other than above C

      • *1: The air shunt valve is malfunctioning

      • *2: The air pressure regulating valve is malfunctioning

    5. Turn the power switch off.


    A

    REPLACE FC STACK ASSEMBLY Click here

    B

    REPLACE FC STACK ASSEMBLY Click here

    C

  9. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / FC / Trouble Codes.

    5. Clear the DTCs.


      Powertrain > FC > Clear DTCs

    6. Turn the power switch off and wait for 3 minutes or more.

      Result
      Proceed to
      NEXT

    NEXT

  10. SIMULATION TEST


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (READY).

    3. Turn the GTS on.

    4. Drive the vehicle for 10 minutes according to the freeze frame data (Vehicle Speed, Accelerator Degree, etc.).

      If vehicle speeds, accelerator pedal positions, road conditions, ambient temperatures and climates at the time the malfunction occurred can be determined, take them into account. Because DTC detection is performed during deceleration (regenerative braking), drive the vehicle in a way so that regenerative braking is performed.

      CAUTION:

      Perform this road test only in an appropriate safe location, in accordance with all local laws.

    5. Enter the following menus: Powertrain / FC / Trouble Codes.

    6. Check for DTCs.


      Powertrain > FC > Trouble Codes
      Result
      Result Proceed to
      DTCs are not output A
      DTC P1D91-450 is output* B

      • *: The air shunt valve is malfunctioning

    7. Turn the power switch off.


    A

    CHECK INTERMITTENT PROBLEMS Click here

    B

    REPLACE FC STACK ASSEMBLY Click here