DTC P1794:00 [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5]

id0102h9569400

Note
•  To determine the malfunctioning part, proceed with the diagnostics from “Function Inspection Using M-MDS”.

Details On DTCs

DESCRIPTION

Capacitor system: Capacitor malfunction
DETECTION CONDITION
Determination conditions
Capacitor malfunction determined
•  When any of the following conditions is met:
―  Capacitor internal resistance exceeds the specified value.
―  Capacitor capacitance exceeds the specified value.
―  Capacitor input voltage exceeds the specified value.
Capacitor deterioration determined
•  When any of the following conditions is met:
―  Capacitor internal resistance exceeds the specified value.
―  Capacitor capacitance decreases below the specified value.
Over-charge determined
•  Capacitor input voltage exceeds the specified value.
Preconditions
•  Not applicable.
Drive cycle
•  1
Self test type
•  CMDTC self test
Sensor used
•  DC-DC converter (i-ELOOP)
FAIL-SAFE FUNCTION
•  Inhibits the i-stop control.
•  Inhibits the i-ELOOP control.
VEHICLE STATUS WHEN DTCs ARE OUTPUT
•  i-stop warning light (amber) flashes
•  The following vehicle conditions differ depending on the malfunction conditions.
―  Master warning light is turned on (illumination during bypass mode by i-ELOOP)
―  Charging system warning light is turned on (illumination while generator output is inhibited)
―  The pre-charge warning is displayed after the engine is started.
POSSIBLE CAUSE
•  Engagement malfunction in capacitor, DC-DC converter (i-ELOOP)
•  Blown capacitor fuse
•  Capacitor malfunction
―  Related wiring harnesses malfunction
―  Capacitor deterioration
•  Generator overcharge (in this case, PCM detects DTC P2504:00)
•  DC-DC converter (i-ELOOP) malfunction
•  PCM malfunction


System Wiring Diagram

•  Not applicable.

Function Explanation (DTC Detection Outline)

•  The capacitor can efficiently store electrical energy generated by the generator.
•  Using the electrical energy stored during deceleration fuel-cut during driving and while i-stop is operating, the power generation load on the generator and the amount of fuel consumption can be reduced.
•  If a malfunction occurs with the capacitor, the generator is connected to the battery and constant charging takes place which could cause the fuel economy to worsen.
•  In this diagnostic, the internal resistance/capacitance is calculated from the capacitor voltage value and charge/discharge current value, and the PCM determines that there is a malfunction in the capacitor-related parts by the internal resistance/capacitance/capacitor voltage exceeding the specified value, and it stores a DTC.

Repeatability Verification Procedure 1

1.  If the negative battery terminal is disconnected, perform the battery condition initial setting (i-stop setting) to complete the i-stop initial setting.
(See BATTERY CONDITION INITIALIZATION SETTING (i-stop SETTING) [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
2.  Start the engine.
3.  Turn off all electrical loads.
4.  Depress the accelerator pedal to increase the engine speed to 3,000 rpm.
5.  Release the accelerator pedal and wait for 1 min while idling.

Repeatability Verification Procedure 2

1.  Stop the engine.
2.  Switch the ignition ON and wait for 1 min.
3.  Switch the ignition OFF (LOCK) and wait for 20 min.
4.  Switch the ignition ON.

PID Item/Simulation Item Used In Diagnosis

PID/DATA monitor item table

Item

Definition

Unit

Condition/Specification
CAP_SYS_10
Open circuit in capacitor (i-ELOOP) (power cannot be supplied from capacitor)
OFF/ON
•  Capacitor internal circuit is not open: Off
•  Capacitor internal circuit is open: On
CAP_SYS 13
Capacitor (i-ELOOP) capacitance malfunction
OFF/ON
•  Capacitor (i-ELOOP) capacitance status is not normal: On
•  Capacitor (i-ELOOP) capacitance status is normal: Off
CAP_SYS 14
Capacitor (i-ELOOP) capacitance deterioration
OFF/ON
•  Capacitor (i-ELOOP) capacitance status deteriorates: On
•  Capacitor (i-ELOOP) capacitance status is normal: Off
CAP_SYS 15
Capacitor (i-ELOOP) internal resistance malfunction
OFF/ON
•  Internal resistance status in capacitor (i-ELOOP) is not normal: On
•  Internal resistance status in capacitor (i-ELOOP) is normal: Off
CAP_SYS 16
Capacitor (i-ELOOP) internal resistance deterioration
OFF/ON
•  Internal resistance status in capacitor (i-ELOOP) deteriorates: On
•  Internal resistance status in capacitor (i-ELOOP) is normal: Off


Function Inspection Using M-MDS

STEP

INSPECTION

RESULTS

ACTION
1
VERIFY RELATED REPAIR INFORMATION AVAILABILITY
•  Verify related Service Bulletins and/or on-line 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
PURPOSE: VERIFY IF POWER SUPPLY IS AFFECTED BY DTC RELATED TO DC-DC CONVERTER (i-ELOOP)
•  Switch the ignition OFF (LOCK), and then switch the ignition ON (engine off).
•  Display the DC-DC converter (i-ELOOP) DTCs using the M-MDS.
•  Is a DTC displayed?
Yes
Repair the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [i-ELOOP].)
Repair the malfunctioning location and go to the troubleshooting procedure to perform the procedure from Step 5.
No
Go to the next step.
3
PURPOSE: VERIFY IF DIAGNOSTIC RESULT IS AFFECTED BY DTC RELATED TO GENERATOR OVERCHARGE OR WIRING HARNESS BETWEEN GENERATOR AND CAPACITOR
•  Perform the DTC inspection for the PCM using the M-MDS.
•  Has DTCs P2502:00, P2503:00, or P2504:00 been recorded?
Yes
Go to the applicable PENDING CODE or DTC inspection.
(See DTC P2502:00 [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
(See DTC P2503:00 [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
(See DTC P2504:00 [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
Repair the malfunctioning location and go to the troubleshooting procedure to perform the procedure from Step 5.
No
Go to the next step.
4
PURPOSE: DETERMINE IF MALFUNCTION IS CAUSED BY CAPACITOR BY VERIFYING PID RELATED TO CAPACITOR
•  Display the following PIDs using the M-MDS.
―  CAP_SYS_10
―  CAP_SYS 13
―  CAP_SYS 14
―  CAP_SYS 15
―  CAP_SYS 16
•  Have all the displayed monitoring values been turned off? Or is the CAP_SYS_10 display on?
Yes
Note
•  A capacitor malfunction due to over-voltage is possible even if all the PIDs displayed in Step 4 indicate “Off”.
•  Because CAP_SYS_10 diagnoses an open circuit in the capacitor, perform diagnosis from Step 1 of the malfunction diagnostic procedure.
Finish the function inspection using the M-MDS and perform diagnosis from Step 1 of the malfunction diagnostic procedure.
No
Go to the next step.
5
PURPOSE: DETERMINE IF MALFUNCTION IS CAUSED BY CAPACITOR BY VERIFYING PID RELATED TO CAPACITOR AGAIN
•  Of the PID values displayed in Step 4, is the CAP_SYS 13 value on?
Yes
Note
•  Because CAP_SYS_13 diagnoses a malfunction related to the capacitor capacitance, replace the capacitor.
Replace the capacitor.
(See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].)
Go to the troubleshooting procedure to perform the procedure from Step 5.
No
Go to the troubleshooting procedure to perform the procedure from Step 4.


Troubleshooting Diagnostic Procedure

Intention of troubleshooting procedure
•  Steps 1 to 3
―  Verify if the malfunction is due to a blown capacitor fuse and poor tightening of the bolts.
•  Step 4
―  Verify if the malfunction is caused by poor engagement of each part.
•  Steps 5 to 7
―  Verify that primary malfunction is resolved and there are no other malfunctions.

Step

Inspection

Results

Action
1
PURPOSE: VERIFY IF MALFUNCTION IS CAUSED BY BLOWN CAPACITOR FUSE
•  Switch the ignition OFF (LOCK).
•  Remove the service plug.
•  Remove the capacitor fuse.
•  Is the capacitor fuse blown?
Yes
Note
•  The procedure may have been performed while the service plug was installed, and the capacitor fuse may have blown.
Replace the capacitor fuse, then go to Step 3.
(See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].)
No
Go to the next step.
2
PURPOSE: VERIFY IF MALFUNCTION IS CAUSED BY POOR TIGHTENING OF BOLTS INSTALLED TO CAPACITOR
•  Verify the bolt tightening condition.
•  Is the bolt tightening condition normal?
Yes
Replace the capacitor, then go to the next step.
(See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].)
No
Tighten the bolts correctly, then go to the next step.
3
PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION
•  Reconnect all disconnected connectors and hoses.
•  Install the service plug.
•  Refer to the [MEMORY CLEARING PROCEDURE] and clear the DTC.
•  Perform the following procedure:
1.  Start the engine.
2.  Wait for 1 min while idling.
3.  Stop the engine.
•  Display the DTCs using the M-MDS.
•  Is DTC P1794:00 displayed?
Yes
If capacitor is not replaced:
•  Replace the capacitor, then perform the malfunction diagnostic procedure in Step 3.
If capacitor is replaced:
•  Perform diagnostic from Step 1 of the “Function inspection using M-MDS”.
―  If the malfunction recurs, replace the PCM, then go to Step 7.
No
Go to Step 6.
4
PURPOSE: VERIFY IF MALFUNCTION IS CAUSED BY POOR ENGAGEMENT OF EACH PART
•  Switch the ignition OFF (LOCK).
•  Remove the service plug.
•  Verify that the following parts are engaged correctly.
―  DC-DC converter (i-ELOOP)
―  Capacitor
•  Is the engagement condition of each part normal?
Yes
Go to the next step.
No
Engage the DC-DC converter (i-ELOOP) or capacitor properly, then go to the next step.
5
PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION
•  Reconnect all disconnected connectors and hoses.
•  Install the service plug.
•  Refer to the [MEMORY CLEARING PROCEDURE] and clear the DTC.
•  Implement repeatability verification procedure 1.
•  Display the DTCs using the M-MDS.
•  Is DTC P1794:00 displayed?
Yes
If capacitor is not replaced:
•  Replace the capacitor, then perform the malfunction diagnostic procedure in Step 5.
If capacitor is replaced:
•  Perform diagnostic from Step 1 of the “Function inspection using M-MDS”.
―  If the malfunction recurs, replace the PCM, then go to Step 7.
No
Go to the next step.
6
PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION
•  Implement repeatability verification procedure 2.
•  Display the DTCs using the M-MDS.
•  Is DTC P1794:00 displayed?
Yes
If capacitor is not replaced:
•  Replace the capacitor, then perform the malfunction diagnostic procedure in Step 5.
If capacitor is replaced:
•  Perform diagnostic from Step 1 of the “Function inspection using M-MDS”.
―  If the malfunction recurs, replace the PCM, then go to the next step.
No
Go to the next step.
7
PURPOSE: VERIFY IF THERE IS ANY OTHER MALFUNCTION
•  Has any other DTC or pending code been stored?
Yes
Repair the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
No
DTC troubleshooting completed.