FC CONTROL SYSTEM, Diagnostic DTC:P1DE4-450

DTC Code	DTC Name
P1DE4-450	FC Coolant Water Temperature Malfunction

DESCRIPTION

The cooling system of the FC system controls the FC stack temperature so that it can remain at optimum for power generation. The cooling system employs the FC cooling water pump assembly to feed the FC stack with a necessary amount of FC stack coolant so that the FC stack temperature can remain at an appropriate level, and it forces a heated FC stack coolant at the FC stack outlet to flow into the radiator, cooling down and recirculating the FC stack coolant.

If a control failure that indicates a loss of cooling function has occurred due to malfunctions of the FC cooling water temperature control valve or a clogged radiator, the FC control ECU will set this DTC.

*1	FC Stack	*2	FC Stack Assembly
*3	FC Cooling Water Pump Assembly	*4	FC Cooling Water Temperature Control Valve
*5	FC Radiator Assembly	*6	Sub-Radiator Assembly
*7	FC Cooling Water Ion Exchanger Assembly	*8	FC Air Compressor with Motor Assembly
*9	Intercooler	*10	Water Temperature Sensor (for Radiator Outlet Side)
*11	Water Temperature Sensor (for FC Stack Outlet Side)	-	-
*a	To the air conditioning heater circuit	-	-

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate
P1DE4-450	FC Coolant Water Temperature Malfunction	Difference between the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" and "Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)" has deviated from a an estimated difference value based on the FC power generation Power consumption of the FC cooling water pump assembly is significantly reduced when compared to the value estimated from the FC cooling water pump assembly RPM. (1 trip detection logic)	Amount of FC stack coolant FC stack coolant piping (leakage) FC cooling water temperature control valve FC radiator assembly (Clogged radiator core) Cooling fan controller with motor	Master Warning Light: Comes on

Tech Tips

This DTC indicates an insufficient amount of FC stack coolant, FC stack coolant leaks, or malfunctions in the FC cooling water temperature control valve or in the cooling fan controller with motor. If a coolant temperature increases high, the FC system output will be limited.
If the FC stack coolant volume decreases, the power consumption of the FC cooling water pump assembly is reduced.

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
P1DE4-450	Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet) Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)

The following items can be helpful when performing repairs:

Data List

Target Radiator Rotary Valve Position
FC Water Pump Revolution
FC Water Pump Consumption Power
Radiator Fan 1 Driving Request
Radiator Fan 2 Driving Request

Common Data List items for FC inspection

Vehicle Speed
Shift Sensor Shift Position
Accelerator Degree
Ready
FC Mode
FC Intermittent Operation
FC Voltage before Boosting
FC Current
Target Low-range Hydrogen Pressure
Smoothed Value of Low-range Hydrogen Pressure
Target Hydrogen Pump Revolution
Hydrogen Pump Revolution
Target FC Stack Air Pressure (FC Stack Inlet)
Smoothed Value of FC Stack Air Pressure (FC Stack Inlet)
Target Mass Air Flow Value
Mass Air Flow Value
Target Air Compressor Revolution
Air Compressor Revolution
Target FC Stack Coolant Temperature (FC Stack Outlet)

Related Active Test
DTC No.	Active Test
P1DE4-450	Radiator Rotary Valve FC Water Pump Radiator Fan1 Radiator Fan2

CAUTION / NOTICE / HINT

Note

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

Forcing the SOC of the EV battery to decrease by applying electrical loads such as turning on the air conditioning (HOT MAX, maximum airflow), or depressing the accelerator pedal with the shift lever in P, the "FC Intermittent Operation" of the Data List is easily to enter OFF (power generation mode).

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

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

CAUTION:

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

PROCEDURE

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.

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / FC / Trouble Codes.

Check for DTCs.

Powertrain > FC > Trouble Codes

Result

Result	Proceed to
P1DE4-450 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
Communication System Malfunction	P1DC9-450	Lost Communication with FC Water Pump Inverter
	P1DF7-450	FC Water Pump Inverter Drive Signal Stuck ON
	P1DF8-450	FC Water Pump Inverter Drive Signal Stuck OFF
Sensor and Actuator Circuit Malfunction	P1D2F-450	FC Water Pump Speed Control Performance
	P1DD5-450	Radiator Rotary Valve Circuit
	P1E47-450	FC Stack Coolant Temperature Sensor (FC Stack Outlet / Radiator Outlet)Correlation
System Malfunction	P1DC8-450	FC Water Pump Inverter Performance

Tech Tips

DTC P1DE4-450 may be set due to problems that cause the DTCs shown above to output. If such happens, troubleshoot the suspected area(s) corresponding to the output DTC(s) in order of the listed DTCs shown in the table above.

Turn the power switch off.

GO TO DTC CHART Click here

CLEAR DTC

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / FC / Trouble Codes.
Clear the DTCs.

Powertrain > FC > Clear DTCs

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

Result

Proceed to
NEXT

CHECK VEHICLE CONDITION

Make sure that the front side of the radiator grille is not blocked with anything.

Ask the customer if the front side of the radiator grille was blocked with anything.

Result

Result	Proceed to
Not blocked.	A
Is/was blocked.	B

Tech Tips

If the radiator grille is blocked, the FC coolant temperature will increase and this DTC may be stored.

IF EQUIPPED, EXPLAIN TO CUSTOMER THAT OPTIONAL COMPONENTS WILL BE REMOVED

CHECK RADIATOR ASSEMBLY

Check that the radiator core is not clogged, deformed or damaged.

OK
Radiator core is not clogged, deformed or damaged.

Result

Proceed to
OK
NG

REPAIR OR REPLACE RADIATOR ASSEMBLY

CHECK COOLANT (FC STACK COOLANT) LEAK

Check the FC stack coolant level in the FC radiator reserve tank.

Check for FC coolant leaks.

Click here

Result

Result	Proceed to
No leaks are found and the FC coolant level in the FC radiator reserve tank is above the low line.	A
No leaks are found and the FC coolant level in the FC radiator reserve tank is below the low line.	B
FC coolant leaks are evident.	C

Tech Tips

After repairing the FC coolant leaks and adding coolant, perform the "FC Water Pump", "Radiator Fan1" and "Radiator Fan2" Active Test (FC Active Test item) and make sure that there are no malfunctions.
If FC stack coolant leaks are not found despite that the remaining FC stack coolant in the radiator reserve tank is below the Low level, leakage may have occurred inside the FC stack (this may cause the EV control ECU to set DTC P0AA6-485).

ADD FC STACK COOLANT

INSPECT COOLANT LEAK AND ADD COOLANT

CHECK COOLANT HOSE

Check that the cooling system hoses are not kinked or clogged.

OK
The cooling system hoses are not kinked or clogged

Result

Proceed to
OK
NG

REPAIR OR REPLACE COOLANT HOSE

PERFORM ACTIVE TEST USING GTS (RADIATOR FAN1, RADIATOR FAN2)

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Enter the following menus: Powertrain / FC / Active Test / Radiator Fan1, Radiator Fan2

Powertrain > FC > Active Test

Tester Display

Radiator Fan1

Powertrain > FC > Active Test

Tester Display

Radiator Fan2
Perform the Active Test.

OK

The cooling fan rotates

Tester Display
Radiator Fan1

Tester Display
Radiator Fan2

OK
The cooling fan rotates

Turn the power switch off.

Result

Proceed to
OK
NG

GO TO COOLING FAN SYSTEM Click here

PERFORM ACTIVE TEST USING GTS (RADIATOR ROTARY VALVE)

Connect the GTS to the DLC3.
Turn the GTS on.
Drive in city streets for approximately 10 minutes to warm up.

Tech Tips

Raise the "Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)" in the Data List to approximately 60°C (140°F)
Enter the following menus: Powertrain / FC / Active Test / Radiator Rotary Valve (1)

Select "FC Mode", "FC Intermittent Operation", "Radiator Fan 1 Driving Request", "Radiator Fan 2 Driving Request", "Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)", "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" and "Target Radiator Rotary Valve Position" in the Data List.

Powertrain > FC > Active Test

Active Test Display
Radiator Rotary Valve

Data List Display
FC Mode
FC Intermittent Operation
Radiator Fan 1 Driving Request
Radiator Fan 2 Driving Request
Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)
Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)
Target Radiator Rotary Valve Position

Turn the power switch on (READY) with the shift lever in P, and check the Data List that "FC Mode" is FC Working and "FC Intermittent Operation" is OFF.
Using Active Tests, set the "Radiator Rotary Valve" to 0%.
Turn the air conditioning on (Lo/COOL MAX, maximum airflow) to actuate the cooling fan of the FC radiator assembly.
Check changes in the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" in the Data List for 1 minute.
Note

If the "Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)" is above 70°C (158°F), perform the operations instructed below to cool it down to approximately 60°C (140°F), and perform the procedure from step (1) again. If the temperature does not decrease, it is suspected that the FC cooling water temperature control valve is malfunctioning.
1. Using Active Tests, set the "Radiator Rotary Valve" to 100%.
2. Turn the air conditioning on to actuate the cooling fan of the FC radiator assembly, allowing the "Smoothed Value of FC Stack Coolant Temperature (FC Stack Outlet)" to decrease to approximately 60°C (140°F).
Tech Tips
- In order to actuate the FC cooling water pump assembly, put the shift lever in P and turn the power switch on (READY) so that the "FC Mode" and "FC Intermittent Operation" in the Data List is in FC Working and OFF respectively.
- If the Active Test "Radiator Rotary Valve" is set to 0%, the FC stack coolant begins circulating without bypassing the FC radiator assembly. Thus, even though the cooling fan is switched between ON and OFF, the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" does not vary virtually.
Turn the air conditioning off to stop the cooling fan of the FC radiator assembly.
Using Active Tests, set the "Radiator Rotary Valve" to 100%.
Turn the air conditioning on (Lo/COOL MAX, maximum airflow) to actuate the cooling fan of the FC radiator assembly.

Check changes in the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" in the Data List for 1 minute.

Tech Tips

In order to actuate the FC cooling water pump assembly, put the shift lever in P and turn the power switch on (READY) so that the "FC Mode" and "FC Intermittent Operation" in the Data List is in FC Working and OFF respectively.
If the Active Test "Radiator Rotary Valve" is set to 100%, the FC stack coolant begins circulating through the radiator assembly. For that reason, the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" decreases when the cooling fan is actuated.

Figure 1. Reference example (Shift lever in P, and the air conditioning is switched between ON and OFF)

Result

Proceed to

Both following conditions 1 and 2 are met:

When the "Target Radiator Rotary Valve Position" is 0%, a decrease in the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" is less than 2°C (36°F) if the air conditioning is turned from OFF to ON
When the "Target Radiator Rotary Valve Position" is 100%, a decrease in the "Smoothed Value of FC Stack Coolant Temperature (Radiator Outlet)" is 2°C (36°F) or more if the air conditioning is turned from OFF to ON

Other than above

Turn the power switch off.

CHECK FOR INTERMITTENT PROBLEMS Click here

REPLACE FC COOLING WATER TEMPERATURE CONTROL VALVE Click here