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2008 - MX-5 - Brakes

NO.4 BOTH ABS WARNING LIGHT AND BRAKE SYSTEM WARNING LIGHT STAY ON 4 S OR MORE WHEN THE IGNITION SWITCH IS TURNED TO THE ON POSITION



4

Both ABS warning light and BRAKE system warning light stay on 4 s or more when the ignition switch is turned to the ON position.

[TROUBLESHOOTING HINTS]

  • ABS HU/CM detects ABS proportioning system malfunction.

  • ABS HU/CM detects low voltage in power supply (ABS CM ignition terminal J voltage is below about 9 to 10 V).

  • ABS HU/CM does not operate.

  • Malfunction of communication network.


Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT ABS HU/CM POWER SUPPLY FUSE
  • Is the ABS HU/CM ignition power supply fuse normal?

Yes

Go to the next step.

No

Inspect for a short to ground on circuit with the blown fuse.

Repair or replace if necessary.

Install appropriate amperage fuse.

2

INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR CONTINUITY AND SHORTS
  • Perform DTC inspection.

  • Is error message displayed regarding communication between ABS HU/CM and M-MDS?

Yes

If a communication error message is displayed even after inspecting according to the procedure displayed on the M-MDS, go to step 10.

No

Go to the next step.

3

INSPECT FOR DTCS IN ABS HU/CM
  • Have DTCs been stored in memory?

Yes

Perform the applicable DTC inspection.

(See ON-BOARD DIAGNOSIS[ABS].)

No

Go to the next step.

4

INSPECT WARNING LIGHT OPERATION
  • Do the ABS and BRAKE system warning light illuminate?

Yes

Go to the next step.

No

Replace the instrument cluster.

(See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)

5

INSPECT ABS HU/CM IGNITION POWER SUPPLY SYSTEM (TERMINAL J)
  • Inspect the voltage for datalogger ABS_VOLT item using the M-MDS.

Specification: approx. 10 V

  • Is the voltage within specification?

Yes

Replace the ABS HU/CM (open or short in ground circuit in ABS HU/CM).

(See ABS HU/CM REMOVAL/INSTALLATION.)

No

Go to the next step.

6

INSPECT BATTERY
  • Is the battery voltage normal?

Yes

Go to the next step.

No

Inspect the battery and charging system.

(See BATTERY INSPECTION [LF].)

(See GENERATOR INSPECTION [LF].)

7

INSPECT CHARGING SYSTEM
  • Is the battery voltage normal with the electrical load (A/C, headlight, etc.) on and the engine idling?

Yes

Go to the next step.

No

Inspect the charging system (drive belt tension, generator, etc.).

(See GENERATOR INSPECTION [LF].)

*8

INSPECT WIRING HARNESS BETWEEN ABS HU/CM POWER SUPPLY AND ABS HU/CM FOR CONTINUITY
  • Disconnect the ABS HU/CM connector.

  • Is the voltage approx. 12 V at connector terminal Z?

Yes

Go to the next step.

No

Inspect the ABS HU/CM connector for secure connection.

*9

INSPECT WIRING HARNESS BETWEEN ABS HU/CM GROUND FOR CONTINUITY
  • Turn the ignition switch to the LOCK position.

  • Is there continuity between connector terminal D and the ground?

Yes

If a malfunction error message is displayed on the M-MDS in Step 1 inspection, go to the next step.

If a malfunction error message is not displayed on the M-MDS in Step 1 inspection, troubleshooting is completed.

No

Repair the wiring harness between ABS HU/CM and ground.

*10

INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR CONTINUITY
  • Is there continuity between connector terminal Z, Y and DLC‐2?

Yes

Go to the next step.

No

Repair the wiring harness between ABS HU/CM and DLC‐2.

*11

INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR SHORT TO BATTERY
  • Is the voltage approx. 12 V at connector terminal Z, Y?

Yes

Repair the wiring harness between ABS HU/CM and DLC‐2.

No

Go to the next step.

*12

INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR SHORT TO GROUND
  • Is there continuity between connector terminal Z, Y and DLC‐2?

Yes

Repair the wiring harness between ABS HU/CM and DLC‐2.

No

Replace the ABS HU/CM (communication circuit malfunction in ABS HU/CM).

(See ABS HU/CM REMOVAL/INSTALLATION.)




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