DTC P1794:16 [START STOP UNIT]

id0902p6023700

Description

Start stop unit power supply voltage (terminal 2W) low input

Detection condition

•  Start stop unit power supply circuit voltage (terminal 2W) of less than 6.5 V is detected for 5 s or more.

Fail-safe function

Not applicable

Possible cause

•  DTCs are stored in the PCM.

•  Battery malfunction

•  Generator malfunction

•  Start stop unit connector or terminal malfunction

•  Start stop unit power supply circuit (terminal 2W) malfunction

―  Short to ground in wiring harness between MAIN 200 A fuse and start stop unit terminal 2W

―  AT 15 A fuse malfunction

―  MAIN 200 A fuse malfunction

―  Open circuit in wiring harness between battery positive terminal and start stop unit terminal 2W

•  Start stop unit malfunction

Description	Start stop unit power supply voltage (terminal 2W) low input
Detection condition	• Start stop unit power supply circuit voltage (terminal 2W) of less than 6.5 V is detected for 5 s or more.
Fail-safe function	Not applicable
Possible cause	• DTCs are stored in the PCM. • Battery malfunction • Generator malfunction • Start stop unit connector or terminal malfunction • Start stop unit power supply circuit (terminal 2W) malfunction ― Short to ground in wiring harness between MAIN 200 A fuse and start stop unit terminal 2W ― AT 15 A fuse malfunction ― MAIN 200 A fuse malfunction ― Open circuit in wiring harness between battery positive terminal and start stop unit terminal 2W • Start stop unit malfunction

Diagnostic Procedure

Step	Inspection		Action
1	VERIFY PCM DTCs • Retrieve the PCM DTCs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-D 1.5].) (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-D 2.2].) (See ON-BOARD DIAGNOSTIC TEST [MZR 1.6].) • Are any DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See DTC TABLE [SKYACTIV-D 1.5].) (See DTC TABLE [SKYACTIV-D 2.2].) (See DTC TABLE [MZR 1.6].)
1		No	Go to the next step.
2	INSPECT BATTERY • Inspect the battery. (See BATTERY INSPECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See BATTERY INSPECTION [SKYACTIV-D 1.5].) (See BATTERY INSPECTION [SKYACTIV-D 2.2].) (See BATTERY INSPECTION [MZR 1.6].) • Is the battery normal?	Yes	Go to the next step.
2		No	Recharge or replace the battery, then go to Step 6. (See BATTERY RECHARGING [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See BATTERY RECHARGING [SKYACTIV-D 1.5].) (See BATTERY RECHARGING [SKYACTIV-D 2.2].) (See BATTERY RECHARGING [MZR 1.6].) (See BATTERY REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See BATTERY REMOVAL/INSTALLATION [SKYACTIV-D 1.5].) (See BATTERY REMOVAL/INSTALLATION [SKYACTIV-D 2.2].) (See BATTERY REMOVAL/INSTALLATION [MZR 1.6].)
3	INSPECT GENERATOR • Inspect the generator. (See GENERATOR INSPECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5 (WITHOUT i-ELOOP)].) (See GENERATOR INSPECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5 (WITH i-ELOOP)].) (See GENERATOR INSPECTION [SKYACTIV-D 1.5].) (See GENERATOR INSPECTION [SKYACTIV-D 2.2 (WITHOUT i-ELOOP)].) (See GENERATOR INSPECTION [SKYACTIV-D 2.2 (WITH i-ELOOP)].) (See GENERATOR INSPECTION [MZR 1.6].) • Is the generator normal?	Yes	Go to the next step.
3		No	Replace the generator, then go to Step 6. (See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5 (WITHOUT i-ELOOP)].) (See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5 (WITH i-ELOOP)].) (See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-D 1.5].) (See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-D 2.2 (WITHOUT i-ELOOP)].) (See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-D 2.2 (WITH i-ELOOP)].) (See GENERATOR REMOVAL/INSTALLATION [MZR 1.6].)
4	INSPECT START STOP UNIT CONNECTOR CONDITION • Switch the ignition off. • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 1.5].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 2.2].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [MZR 1.6].) • Disconnect the start stop unit connector. • Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection. • Is the connector normal?	Yes	Go to the next step.
4		No	Repair or replace the connector, then go to Step 6.
5	VERIFY START STOP UNIT POWER SUPPLY VOLTAGE (TERMINAL 2W) • Always reconnect all disconnected connectors. • Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 1.5].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 2.2].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [MZR 1.6].) • Display PID VPWR_B2 using the M-MDS. (See PID/DATA MONITOR INSPECTION [START STOP UNIT].) • Is the voltage B+?	Yes	Go to the next step.
5		No	Inspect the AT 15 A fuse and MAIN 200 A fuse. • If the fuse is blown: ― Refer to the wiring diagram and verify whether or not there is a common connector between MAIN 200 A fuse and start stop unit terminal 2W. If there is a common connector: • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has a short to ground. • Replace the fuse. • If the fuse is damaged: ― Replace the fuse. • If the fuse is normal: ― Refer to the wiring diagram and verify whether or not there is a common connector between battery positive terminal and start stop unit terminal 2W. If there is a common connector: • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has an open circuit. Go to the next step.
6	VERIFY THAT REPAIRS HAVE BEEN COMPLETED • Always reconnect all disconnected connectors. • Reconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 1.5].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-D 2.2].) (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [MZR 1.6].) • Clear the DTC for the start stop unit using the M-MDS. (See CLEARING DTC [START STOP UNIT].) • Switch the ignition ON (engine off or on) and wait for 5 s or more. • Retrieve the start stop unit DTCs using the M-MDS. (See DTC INSPECTION [START STOP UNIT].) • Is the same DTC displayed?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the start stop unit. (See START STOP UNIT REMOVAL/INSTALLATION.) Go to the next step.
6		No	Go to the next step.
7	VERIFY IF OTHER DTCs DISPLAYED • Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [START STOP UNIT].)
7		No	DTC troubleshooting completed.