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Home >> Mazda >> 2017 >> CX-5 Grand Select, FWD >> Repair and Diagnosis >> Body & Frame >> Door Locks >> On-Board Diagnostic - Start Stop Unit >> DTC U0028-87; Communication Error With Rear Body Control Module (RBCM) >> Diagnostic Procedure

Diagnostic Procedure

DTC U0028-87; COMMUNICATION ERROR WITH REAR BODY CONTROL MODULE (RBCM) DIAGNOSTIC PROCEDURE

Step Inspection Action
1 INSPECT REAR BODY CONTROL MODULE (RBCM) CONNECTOR CONDITION
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Disconnect the rear body control module (RBCM) 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 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 6.
3 INSPECT REAR BODY CONTROL MODULE (RBCM) CIRCUIT FOR SHORT TO GROUND
  • Verify that the rear body control module (RBCM) and start stop unit connectors are disconnected.
  • Inspect for continuity between rear body control module (RBCM) terminal 3B (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 1Q and rear body control module (RBCM) terminal 3B.
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 REAR BODY CONTROL MODULE (RBCM) CIRCUIT FOR OPEN CIRCUIT
  • Verify that the rear body control module (RBCM) and start stop unit connectors are disconnected.
  • Inspect for continuity between start stop unit terminal 1Q (wiring harness-side) and rear body control module (RBCM) terminal 3B (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 1Q and rear body control module (RBCM) terminal 3B.
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 VERIFY IF MALFUNCTIONING LOCATION IS REAR BODY CONTROL MODULE (RBCM) DEPENDING ON REPEATABILITY Yes Replace the rear body control module (RBCM), then Go to the next step.
(See REAR BODY CONTROL MODULE (RBCM) REMOVAL/INSTALLATION .)
No Go to Step 7.
6 VERIFY THAT REPAIRS HAVE BEEN COMPLETED Yes Repeat the inspection from Step 1.
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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