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DTC P1794:16 [START STOP UNIT]

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2016 – MX-5 – Body and Accessories

DTC P1794:16 [START STOP UNIT]

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

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

Yes

Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

Go to the next step.

2

INSPECT BATTERY

Yes

Go to the next step.

No

Recharge or replace the battery, then go to Step 6.

(See BATTERY RECHARGING.)

(See BATTERY REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

3

INSPECT GENERATOR

Yes

Go to the next step.

No

Replace the generator, then go to Step 6.

(See GENERATOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

4

INSPECT START STOP UNIT CONNECTOR CONDITION

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • 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.

No

Repair or replace the connector, then go to Step 6.

5

VERIFY START STOP UNIT POWER SUPPLY VOLTAGE (TERMINAL 2W)

Yes

Go to the next step.

No

Inspect the AT 15 A fuse and MAIN 200 A fuse.

  • Any 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.

  • Any fuse is damaged:

    • Replace the fuse.

  • All fuses are 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

Yes

Repeat the inspection from Step 1.

Go to the next step.

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].)

No

DTC troubleshooting completed.

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