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Home >> Toyota >> 2017 >> Mirai >> Repair and Diagnosis (Single Page) >> Hybrid/Electric Powertrain >> Testing and Diagnosis >> Fuel Cell (FC) Control System - Diagnostic Codes (1 Of 3) >> FC Control System >> DTC P1D8C-450: FC Stack Air Temperature Sensor (FC Stack Inlet) Circuit Low; DTC P1D8D-450: FC Stack Air Temperature Sensor (FC Stack Inlet) Circuit High [06/2015 - ] >> Description
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DTC P1D8C-450: FC Stack Air Temperature Sensor (FC Stack Inlet) Circuit Low; DTC P1D8D-450: FC Stack Air Temperature Sensor (FC Stack Inlet) Circuit High [06/2015 - ]: Description

The FC gas temperature sensor is provided on the FC air compressor with motor assembly, and is used to monitor air temperature cooled down by the intercooler. The FC gas temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the FC control ECU as voltage changes.

The FC gas temperature sensor is connected to the FC control ECU, and a power voltage of 5 V is supplied from the ATIC terminal of the FC control ECU to the sensor via resistor R. Since resistor R and the sensor are connected in series, resistance varies as an intake air temperature changes, and potential of the ATIC terminal also varies.

GTY598658Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate
P1D8C-450 FC Stack Air Temperature Sensor (FC Stack Inlet) Circuit Low If the +B voltage is not low when the power switch is turned on (IG), FC Stack Air Temperature Sensor (FC Stack Inlet) Voltage remains at less than 0.1 V for more than 3 seconds.
(1 trip detection logic)
  • FC gas temperature sensor
  • FC control ECU
  • Wire harness or connector
Master Warning Light: Comes on
P1D8D-450 FC Stack Air Temperature Sensor (FC Stack Inlet) Circuit High If all of the following conditions are met, and FC Stack Air Temperature Sensor (FC Stack Inlet) Voltage remains at more than 4.95 V for more than 3 seconds.
  • FC Mode is in FC Startup Process or FC Working
  • Intake air temperature is more than 20°C (68°F)
  • Mass air flow meter is normal
  • +B voltage is not low

(1 trip detection logic)
  • FC gas temperature sensor
  • FC control ECU
  • Wire harness or connector
Master Warning Light: Comes on
DETECTION TIMING: P1D8C-450

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 -
DETECTION TIMING: P1D8D-450

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 - -

HINT: 

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
P1D8C-450
  • FC Stack Air Temperature Sensor (FC Stack Inlet) Voltage
  • Smoothed Value of FC Stack Air Temperature (FC Stack Inlet)
P1D8D-450

The following items can be helpful when performing repairs:

Data List