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DTC B13C3:16 [START STOP UNIT]

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2016 – MX-5 – Body and Accessories

DTC B13C3:16 [START STOP UNIT]

Description

LF control unit power supply voltage low input

Detection condition

  • Start stop unit power supply circuit voltage of 8.5 V or more or less than 16.5 V and LF control unit power supply circuit voltage of 5 V or more or less than 8.5 V are detected for 5 s or more.

Fail-safe

  • Inhibits the door lock/unlock control using the advanced keyless entry system.

Possible cause

  • LF control unit connector or terminal malfunction

  • Malfunction between battery positive terminal and LF control unit terminal B

  • LF control unit malfunction

  • Start stop unit malfunction

Diagnostic Procedure

Step

Inspection

Action

1

INSPECT LF CONTROL UNIT CONNECTOR CONDITION

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Disconnect the LF control 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 4.

2

VERIFY LF CONTROL UNIT POWER SUPPLY VOLTAGE

  • Always reconnect all disconnected connectors.

  • Connect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Measure the voltage at the LF control unit terminal B (wiring harness-side).

  • Is the voltage 5 V or more or less than 8.5 V?

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between battery positive terminal and LF control unit terminal B.

    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 malfunction.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Inspect the wiring harness between battery positive terminal and LF control unit terminal B.

Go to Step 4.

No

Go to the next step.

3

INSPECT LF CONTROL UNIT

Yes

Go to the next step.

No

Replace the LF control unit, then go to the next step.

(See LF CONTROL UNIT REMOVAL/INSTALLATION.)

4

VERIFY THAT REPAIRS HAVE BEEN COMPLETED

Yes

Repeat the inspection from Step 1.

Go to the next step.

No

Go to the next step.

5

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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