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Home >> Mazda >> 2017 >> 6 Touring, Automatic Trans >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Anti-Theft Systems >> On-Board Diagnostic - Start Stop Unit >> DTC B13C3-29; Communication Error Between Start Stop Unit And LF Control Unit >> Diagnostic Procedure
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Diagnostic Procedure

DIAGNOSTIC PROCEDURE

Step Inspection Action
1 INSPECT LF CONTROL UNIT CONNECTOR
  • Switch the ignition off.
  • Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.5] .)
  • 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 6.
2 INSPECT START STOP UNIT CONNECTOR
  • 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.
3 INSPECT FOR SHORT TO GROUND IN WIRING HARNESS BETWEEN START STOP UNIT AND LF CONTROL UNIT
  • Verify that the start stop unit and LF control unit connectors are disconnected.
  • Inspect for continuity between LF control unit terminal I (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 start stop unit terminal 2F and LF control unit terminal I.
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 6.
No Go to the next step.
4 INSPECT FOR OPEN CIRCUIT IN WIRING HARNESS BETWEEN START STOP UNIT AND LF CONTROL UNIT
  • Verify that the start stop unit and LF control unit connectors are disconnected.
  • Inspect for continuity between start stop unit terminal 2F (wiring harness-side) and LF control unit terminal I (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 start stop unit terminal 2F and LF control unit terminal I.
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 6.
5 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 .)
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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