DTC P1794:00 [SKYACTIV-G 2.5]

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2014 - Mazda6 - Engine

DTC P1794:00 [SKYACTIV-G 2.5]

NOTE:

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

Details On DTCs


DESCRIPTION	Capacitor (i-ELOOP) system: Capacitor (i-ELOOP) malfunction
DETECTION CONDITION	Determination conditions	Capacitor malfunction determined Any one of the following conditions is met: Capacitor (i-ELOOP) internal resistance exceeds the specification. Capacitor (i-ELOOP) capacitance exceeds the specification. Capacitor (i-ELOOP) voltage exceeds the specification. Capacitor (i-ELOOP) deterioration determined Any one of the following conditions is met: Capacitor (i-ELOOP) internal resistance exceeds the specification. Capacitor (i-ELOOP) capacitance is less the than specification. Over-charge determined Capacitor (i-ELOOP) voltage exceeds the specification.
	Preconditions	Not applicable.
	Drive cycle	1
	Self test type	CMDTC self test
	Sensor used	DC-DC converter
FAIL-SAFE FUNCTION	Inhibits the i-ELOOP control.
VEHICLE STATUS WHEN DTCs ARE OUTPUT	The following vehicle conditions differ depending on the type of malfunction Master warning light is illuminated (illumination during bypass mode by i-ELOOP) Charging system warning light is illuminated (illumination while generator output is inhibited) Pre-charge warning is displayed after the engine is started.
POSSIBLE CAUSE	Engagement malfunction in capacitor (i-ELOOP), DC-DC converter Capacitor (i-ELOOP) malfunction Capacitor (i-ELOOP) deterioration Generator overcharge (in this case, PCM detects DTC P2504:00) DC-DC converter malfunction PCM malfunction

System Wiring Diagram

Not applicable.

Function Explanation (DTC Detection Outline)

The capacitor (i-ELOOP) can store generated electrical energy from the generator efficiently.

The electrical energy stored during deceleration fuel-cut is used during driving, which reduces the power generating load on the generator and the amount of fuel consumption.

If a malfunction occurs with the capacitor (i-ELOOP), constant charging takes place by operation of the bypass mode which could cause the fuel economy to worsen.

In this diagnostic, the internal resistance/capacitance is calculated from the capacitor (i-ELOOP) voltage value and charge/discharge current value, and the PCM determines that there is a malfunction in the battery-related parts by the internal resistance/capacitance/capacitor (i-ELOOP) voltage exceeding the specified value, and it stores a DTC.

Repeatability Verification Procedure

Start the engine.(no electrical load)

Wait for 20 min (idle).

Depress the accelerator pedal to increase the engine speed to 3,000 rpm.

Release the accelerator pedal to idle the engine.

Stop the engine.

Switch the ignition on and wait for 1 min.

Switch the ignition off and wait for 20 min.

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.
1		No	Go to the next step.
2	PURPOSE: VERIFY IF POWER SUPPLY IS AFFECTED BY DTC RELATED TO DC-DC CONVERTER Switch the ignition off, then ON (engine off). Perform the DC-DC converter DTC inspection using the M-MDS. (See DTC INSPECTION [i-ELOOP].) Are any DTCs present?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [i-ELOOP].)
2		No	Go to the next step.
3	PURPOSE: VERIFY IF DIAGNOSTIC RESULT IS AFFECTED BY DTC RELATED TO GENERATOR OVERCHARGE Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].) Is the PENDING CODE/DTC P2504:00 also present?	Yes	Go to the applicable PENDING CODE or DTC inspection. (See DTC P2504:00 [SKYACTIV-G 2.5].)
3		No	Go to the next step.
4	PURPOSE: DETERMINE IF THE MALFUNCTION IS CAUSED BY CAPACITOR (i-ELOOP) BY VERIFYING THE PID RELATED TO THE CAPACITOR (i-ELOOP) Access the following PIDs using the M-MDS (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].) CAP_SYS_10 CAP_SYS 13 CAP_SYS 14 CAP_SYS 15 CAP_SYS 16 Are all of the PID item “CAP_SYS_10, CAP_SYS 13, CAP_SYS 14, CAP_SYS 15, CAP_SYS 16” values off?	Yes	NOTE: If excessive voltage is applied to the capacitor, all the PIDs displayed in Step 4 indicate “Off”, and the PCM determines a capacitor malfunction and stores DTC P1794:00. Replace the capacitor (i-ELOOP). (See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].) Go to the troubleshooting procedure to perform the procedure from Step 2.
4		No	Go to the next step.
5	PURPOSE: DETERMINE IF THE MALFUNCTION IS CAUSED BY CAPACITOR (i-ELOOP) BY VERIFYING THE PID RELATED TO THE CAPACITOR (i-ELOOP) Are all of the PID item “CAP_SYS_10, CAP_SYS 13” values on?	Yes	Replace the capacitor (i-ELOOP). (See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].) Go to the troubleshooting procedure to perform the procedure from Step 2.
5		No	Go to the troubleshooting procedure to perform the procedure from Step 1.

Troubleshooting Diagnostic Procedure

Intention of troubleshooting procedure

Step 1

Verify the engagement condition of each part.

Step 2—3

Verify that the primary malfunction is resolved and there are no other malfunctions.


STEP	INSPECTION	RESULTS	ACTION
1	PURPOSE: VERIFY IF MALFUNCTION CAUSED BY ENGAGEMENT MALFUNCTION OF EACH PART Switch the ignition off. Disconnect the service plug. (See SERVICE PLUG DISCONNECTION/CONNECTION [i-ELOOP].) Verify that the following parts are engaged correctly. DC-DC converter (See DC-DC CONVERTER REMOVAL/INSTALLATION [i-ELOOP].) Capacitor (i-ELOOP) (See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].) Is the engagement condition of each part normal?	Yes	Go to the next step.
1		No	Tighten the DC-DC converter or capacitor (i-ELOOP) properly, then go to the next step.
2	PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION Always reconnect all disconnected connectors. Reconnect the service plug. (See SERVICE PLUG DISCONNECTION/CONNECTION [i-ELOOP].) Clear the DTC from the PCM memory using the M-MDS. (See CLEARING DTC [SKYACTIV-G 2.5].) Implement the repeatability verification procedure. (See Repeatability Verification Procedure.) Perform the DTC Reading Procedure. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].) Is the same DTC present?	Yes	Replace the capacitor (i-ELOOP) and verify that the repairs have been completed in Step 2. (See CAPACITOR (i-ELOOP) REMOVAL/INSTALLATION [i-ELOOP].) If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.5].) Go to the next step.
2		No	Go to the next step.
3	PURPOSE: VERIFY IF THERE IS ANY OTHER MALFUNCTION Is any other DTC or pending code stored?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [SKYACTIV-G 2.5].)
3		No	DTC troubleshooting completed.

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