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Home >> Mazda >> 2022 >> MX-5 Miata RF Club >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> On-Board Diagnostic - Electric Supply Unit (ESU) >> DTC B1207-86: Error Signal Received From SAS Control Module [Electrical Supply Unit (ESU)] >> Diagnostic Procedure

Diagnostic Procedure

DTC B1207:86 (ELECTRICAL SUPPLY UNIT) DIAGNOSTIC PROCEDURE

Step Inspection Action
1 INSPECT SAS CONTROL MODULE CONNECTOR CONDITION 
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Disconnect the SAS control module 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.
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 7.
3 INSPECT WIRING HARNESS BETWEEN SAS CONTROL MODULE AND ELECTRICAL SUPPLY UNIT (ESU) FOR SHORT TO GROUND 
  • Verify that the SAS control module and electrical supply unit (ESU) connectors are disconnected.
  • Inspect for continuity between SAS control module terminal 3X (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 SAS control module terminal 3X and electrical supply unit (ESU) terminal 2H.
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 7.
No Go to the next step.
4 INSPECT WIRING HARNESS BETWEEN SAS CONTROL MODULE AND ELECTRICAL SUPPLY UNIT (ESU) FOR SHORT TO POWER SUPPLY 
  • Verify that the SAS control module and electrical supply unit (ESU) connectors are disconnected.
  • Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Switch the ignition ON (engine off or on).
  • Measure the voltage at the SAS control module terminal 3X (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 SAS control module terminal 3X and electrical supply unit (ESU) terminal 2H.
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 7.
5 INSPECT WIRING HARNESS BETWEEN SAS CONTROL MODULE AND ELECTRICAL SUPPLY UNIT (ESU) FOR OPEN CIRCUIT 
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Verify that the SAS control module and electrical supply unit (ESU) connectors are disconnected.
  • Inspect the wiring harness for continuity between SAS control module terminal 3X (wiring harness-side) and electrical supply unit (ESU) terminal 2H (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 SAS control module terminal 3X and electrical supply unit (ESU) terminal 2H.
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 7.
6 VERIFY IF MALFUNCTIONING LOCATION IS SAS CONTROL MODULE DEPENDING ON REPEATABILITY 
Yes Replace the SAS control module, then go to the next step.
 
(See SAS CONTROL MODULE REMOVAL/INSTALLATION [TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.] .)
No Go to Step 8.
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.