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Home >> Mazda >> 2017 >> CX-3 Touring, AWD >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> On-Board Diagnostic - Electrical Supply Unit >> DTC B1277-11; Back-Up Light Circuit Malfunction >> Diagnostic Procedure

Diagnostic Procedure

DTC B1277-11; BACK-UP LIGHT CIRCUIT MALFUNCTION - DIAGNOSTIC PROCEDURE

Step Inspection Action
1 VISUALLY INSPECT BACK-UP LIGHT BULB (LH)
  • Visually inspect the back-up light bulb (LH).
  • Is the back-up light bulb (LH) normal?
Yes Go to the next step.
No Replace the back-up light bulb (LH), then go to Step 7.
(See BACK-UP LIGHT BULB REMOVAL/INSTALLATION .)
2 VISUALLY INSPECT BACK-UP LIGHT BULB (RH)
  • Visually inspect the back-up light bulb (RH).
  • Is the back-up light (RH) normal?
Yes Go to the next step.
No Replace the back-up light bulb (RH), then go to Step 7.
(See BACK-UP LIGHT BULB REMOVAL/INSTALLATION .)
3 INSPECT BACK-UP LIGHT (LH) CONNECTOR CONDITION
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
  • Disconnect the back-up light (LH) 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 7.
4 INSPECT BACK-UP LIGHT (RH) CONNECTOR CONDITION
  • Disconnect the back-up light (RH) 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 7.
5 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 7.
6 INSPECT BACK-UP LIGHT CONTROL CIRCUIT FOR SHORT TO GROUND
  • Verify that the back-up light (LH)/(RH) and electrical supply unit (ESU) connectors are disconnected.
  • Inspect for continuity between electrical supply unit (ESU) terminal 2Q (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 the following terminals:
  • Electrical supply unit (ESU) terminal 2Q- Back-up light (LH) terminal A
  • Electrical supply unit (ESU) terminal 2Q- Back-up light (RH) terminal A

    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 the next step.
No Go to the next step.
7 VERIFY THAT REPAIRS HAVE BEEN COMPLETED Yes Repeat the inspection from Step 1.
Go to the next step.
No Go to the next step.
8 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.