Knowledge Base

Free to use workshop manual for your 2015+ Mk4 'ND' Mazda MX-5
Home

 

< Previous   Next >

DTC B1142:13 [ELECTRICAL SUPPLY UNIT (ESU)]

Description

Ignition switch status mismatch

Detection condition

  • The electrical supply unit (ESU) detects the following mismatches.

    • Ignition switch status determined from power supply condition in BCM received from BCM via LIN communication

    • Ignition switch status determined from power supply input condition of electrical supply unit (ESU) power supply circuit (IG1)

Fail-safe

Not applicable

Possible cause

  • BCM connector or terminal malfunction

  • Electrical supply unit (ESU) connector or terminal malfunction

  • BCM power supply circuit (IG1) malfunction

    • Short to ground in the wiring harness between METER1 10 A fuse and BCM terminal 3O

    • METER1 10 A fuse malfunction

    • Open circuit in wiring harness between IG1 relay terminal C and BCM terminal 3O

  • Electrical supply unit (ESU) power supply circuit (IG1) malfunction

    • Short to ground in the wiring harness between METER1 10 A fuse and electrical supply unit (ESU) terminal 1H

    • METER1 10 A fuse malfunction

    • Open circuit in wiring harness between IG1 relay terminal C and electrical supply unit (ESU) terminal 1H

  • Short to ground in wiring harness between BCM terminal 2Y and electrical supply unit (ESU) terminal 2I

  • Short to power supply in wiring harness between BCM terminal 2Y and electrical supply unit (ESU) terminal 2I

  • Open circuit in wiring harness between BCM terminal 2Y and electrical supply unit (ESU) terminal 2I

  • BCM malfunction

  • Electrical supply unit (ESU) malfunction

Diagnostic Procedure

Step

Inspection

Action

1

 INSPECT BCM CONNECTOR CONDITION

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Disconnect the BCM 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 9.

2

 INSPECT ELECTRICAL SUPPLY UNIT (ESU) CONNECTOR CONDITION

  • Disconnect the electrical supply unit (ESU) 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 9.

3

 VERIFY BCM POWER SUPPLY (IG1) VOLTAGE

Yes

Go to the next step.

No

Inspect the METER1 10 A fuse.

  • If the fuse is blown:

    • Refer to the wiring diagram and verify whether or not there is a common connector between METER1 10 A fuse and BCM terminal 3O.

        • 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 IG1 relay terminal C and BCM terminal 3O.

        • 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 Step 9.

4

 VERIFY ELECTRICAL SUPPLY UNIT (ESU) POWER SUPPLY (IG1) VOLTAGE

  • Measure the voltage at the electrical supply unit (ESU) terminal 1H (wiring harness-side).

  • Is the voltage B+?

Yes

Go to the next step.

No

Inspect the METER1 10 A fuse.

  • If the fuse is blown:

    • Refer to the wiring diagram and verify whether or not there is a common connector between METER1 10 A fuse and electrical supply unit (ESU) terminal 1H.

        • 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 IG1 relay terminal C and electrical supply unit (ESU) terminal 1H.

        • 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 Step 9.

5

 INSPECT LIN COMMUNICATION CIRCUIT BETWEEN BCM AND ELECTRICAL SUPPLY UNIT (ESU) FOR SHORT TO GROUND

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Verify that the BCM and electrical supply unit (ESU) connectors are disconnected.

  • Inspect for continuity between BCM terminal 2Y (wiring harness-side) and body ground.

  • Is there continuity?

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between BCM terminal 2Y and electrical supply unit (ESU) terminal 2I.

    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.

Go to Step 9.

No

Go to the next step.

6

 INSPECT LIN COMMUNICATION CIRCUIT BETWEEN BCM AND ELECTRICAL SUPPLY UNIT (ESU) FOR SHORT TO POWER SUPPLY

  • Verify that the BCM and electrical supply unit (ESU) connectors are disconnected.

  • Connect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Switch the ignition ON (engine off or on).

  • Measure the voltage at the BCM terminal 2Y (wiring harness-side).

  • Is the voltage 0 V?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between BCM terminal 2Y and electrical supply unit (ESU) terminal 2I.

    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 power supply.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has a short to power supply.

Go to Step 9.

7

 INSPECT LIN COMMUNICATION CIRCUIT BETWEEN BCM AND ELECTRICAL SUPPLY UNIT (ESU) FOR OPEN CIRCUIT

  • Switch the ignition off.

  • Disconnect the negative battery cable.

    (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION.)

  • Verify that the BCM and electrical supply unit (ESU) connectors are disconnected.

  • Inspect the wiring harness for continuity between BCM terminal 2Y (wiring harness-side) and electrical supply unit (ESU) terminal 2I (wiring harness-side).

  • Is there continuity?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between BCM terminal 2Y and electrical supply unit (ESU) terminal 2I.

    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 Step 9.

8

 VERIFY IF MALFUNCTIONING LOCATION IS BCM DEPENDING ON REPEATABILITY

Yes

Replace the BCM, then go to the next step.

(See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION.)

No

Go to Step 10.

9

 VERIFY THAT REPAIRS HAVE BEEN COMPLETED

Yes

Repeat the inspection from Step 1.

Go to the next step.

No

Go to the next step.

10

 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 [ELECTRICAL SUPPLY UNIT (ESU)].)

No

DTC troubleshooting completed.
< Previous   Next >
 

Free to use workshop manual for your 2015+ Mk4 'ND' Mazda MX-5

COPYRIGHT NOTICE:
This fan site is not affiliated with Mazda, and is intended for personal, or commercial use only. The content of our web pages is for general information purposes only and is presented “as is”. We give no assurance or warranty regarding the accuracy of the contents. Readers should do their due diligence and seek the advice of an appropriately certified automotive technician before attempting any steps on this site. Original content provided by Mazda North America. The content of the manual is copyright under DMCA to: full.metal.resistor@gmail.com
LIMITATION OF LIABILITY:
We accept no responsibility for errors, inaccuracies, or omissions found on these pages. Additionally, we hereby exclude liability for any demands, claims, damages or losses of any kind with regard to any content or information provided on our web-site, including but not limited to incidental or consequential damages, direct or indirect loss, compensatory damages, loss of profits, or otherwise. By using this manual you assume full liablity for any procedures carried out on your vehicle, and are responsible for the vehicle remaining road legal and safe.