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Home >> Mazda >> 2023 >> CX-5 Turbo >> Repair and Diagnosis >> Brakes >> Parking Brake System >> On-Board Diagnostic - Electric Parking Brake >> DTC C1128-29: Electric Parking Brake Switch Circuit Malfunction [Electric Parking Brake Control Module] >> Diagnostic Procedure

Diagnostic Procedure

DTC C1128:29 (ELECTRIC PARKING BRAKE CONTROL MODULE) DIAGNOSTIC PROCEDURE

Step Inspection Results Action
1 INSPECT ELECTRIC PARKING BRAKE SWITCH CONNECTOR CONDITION 
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Disconnect the electric parking brake switch 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 ELECTRIC PARKING BRAKE SWITCH  Yes Go to the next step.
No Replace the electric parking brake switch, then go to Step 7. (See ELECTRIC PARKING BRAKE SWITCH REMOVAL/INSTALLATION .)
3 INSPECT ELECTRIC PARKING BRAKE CONTROL MODULE CONNECTOR CONDITION 
  • Disconnect the electric parking brake switch 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 ELECTRIC PARKING BRAKE SWITCH CIRCUIT FOR SHORT TO POWER SUPPLY 
  • Verify that the electric parking brake switch and electric parking brake control module 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 following terminals (wiring harness-side):
    • Electric parking brake switch terminal C
    • Electric parking brake switch terminal E
    • Electric parking brake switch terminal G
    • Electric parking brake switch terminal H
  • 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 the following terminals:
  • Electric parking brake switch terminal C-Electric parking brake control module terminal 2K
  • Electric parking brake switch terminal E-Electric parking brake control module terminal 2Q
  • Electric parking brake switch terminal G-Electric parking brake control module terminal 2L
  • Electric parking brake switch terminal H-Electric parking brake control module terminal 1W

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 ELECTRIC PARKING BRAKE SWITCH CIRCUIT FOR OPEN CIRCUIT 
  • Switch the ignition off.
  • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
  • Verify that the electric parking brake switch and electric parking brake control module connectors are disconnected.
  • Inspect for continuity between the following terminals (wiring harness-side):
    • Electric parking brake switch terminal C-Electric parking brake control module terminal 2K
    • Electric parking brake switch terminal E-Electric parking brake control module terminal 2Q
    • Electric parking brake switch terminal G-Electric parking brake control module terminal 2L
    • Electric parking brake switch terminal H-Electric parking brake control module terminal 1W
  • 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 the following terminals:
  • Electric parking brake switch terminal C-Electric parking brake control module terminal 2K
  • Electric parking brake switch terminal E-Electric parking brake control module terminal 2Q
  • Electric parking brake switch terminal G-Electric parking brake control module terminal 2L
  • Electric parking brake switch terminal H-Electric parking brake control module terminal 1W

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 INSPECT ELECTRIC PARKING BRAKE SWITCH CIRCUITS FOR SHORT CIRCUIT 
  • Verify that the electric parking brake switch and electric parking brake control module connectors are disconnected.
  • Inspect for continuity between electric parking brake switch terminals C, E, G, and H (wiring harness-side).
  • Is there continuity?
Yes Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
  • Electric parking brake switch terminal C-Electric parking brake control module terminal 2K
  • Electric parking brake switch terminal E-Electric parking brake control module terminal 2Q
  • Electric parking brake switch terminal G-Electric parking brake control module terminal 2L
  • Electric parking brake switch terminal H-Electric parking brake control module terminal 1W

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 each other.
  • Repair or replace the malfunctioning part.

If there is no common connector: 
  • Repair or replace the wiring harness which has a short to each other.

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 [ELECTRIC PARKING BRAKE CONTROL MODULE] .)
No DTC troubleshooting completed.