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Home >> Mazda >> 2023 >> MX-5 Miata Club >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> On-Board Diagnostic - Start Stop Unit >> DTC B108C-23: Push Button Start Switch 2 Circuit Malfunction [Start Stop Unit] >> Diagnostic Procedure

Diagnostic Procedure

DTC B108C:23 (START STOP UNIT) DIAGNOSTIC PROCEDURE

Step Inspection Action
1 INSPECT PUSH BUTTON START CONNECTOR CONDITION 
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Disconnect the push button start 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 5.
2 INSPECT START STOP UNIT CONNECTOR CONDITION 
  • 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 5.
3 INSPECT PUSH BUTTON START SWITCH 2 CIRCUIT FOR SHORT TO GROUND 
  • Verify that the push button start and start stop unit connectors are disconnected.
  • Inspect for continuity between push button start 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 2J and push button start 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 5.
No Go to the next step.
4 INSPECT PUSH BUTTON START SWITCH 2  Yes Go to the next step.
No Replace the push button start, then go to the next step. (See PUSH BUTTON START REMOVAL/INSTALLATION .)
5 VERIFY THAT REPAIRS HAVE BEEN COMPLETED  Yes Repeat the inspection from Step 1.
No Go to the next step.
6 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.