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 [ABS]

id0403a5802000

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
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POSSIBLE CAUSE | • ABS HU/CM power supply fuse malfunction ― Short to ground in ABS HU/CM power supply circuit ― ABS HU/CM power supply fuse malfunction • ABS HU/CM DTC is stored • Instrument cluster malfunction • ABS HU/CM malfunction (open or short circuit in ABS HU/CM internal ground circuit) • Battery malfunction • Charging system malfunction • ABS HU/CM looseness • Open circuit in wiring harness between ABS HU/CM terminal D and body ground • Open circuit in wiring harness between ABS HU/CM terminal Y, Z and DLC-2 • Short to power supply in wiring harness between ABS HU/CM terminal D and body ground • Short to ground in wiring harness between ABS HU/CM terminal D and body ground • ABS HU/CM malfunction (ABS HU/CM internal communication circuit malfunction)

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | INSPECT ABS HU/CM POWER SUPPLY FUSE • Turn the ignition switch off. • Inspect the ABS HU/CM power supply fuse. • Is there any malfunction? | Yes | Inspect the blown fuse related wiring harness for short to ground. Repair or replace the wiring harness for a possible short to ground, if necessary. Install the appropriate amperage fuse.
No | Go to the next step.
2 | INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR CONTINUITY AND SHORTS • Perform the Reading DTCs Procedure. (See ON-BOARD DIAGNOSIS [ABS].) • Is the 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 | CONFIRM ABS HU/CM DTC • Perform the Reading DTCs Procedure. (See ON-BOARD DIAGNOSIS [ABS].) • Are any DTC present? | Yes | Go to the applicable DTC inspection. (See ON-BOARD DIAGNOSIS [ABS].)
No | Go to the next step.
4 | INSPECT WARNING LIGHT OPERATION • Turn on the all warning light on instrument cluster using the instrument cluster input/output check code 26. (See INSTRUMENT CLUSTER INPUT/OUTPUT CHECK MODE.) • 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 • Perform the PID/Data Monitor and Record Procedure and access the ABS_VOLT PID. (See ON-BOARD DIAGNOSIS [ABS].) • Is the voltage within the specification? Specification: approx. 10 V | Yes | Replace the ABS HU/CM (open or short circuit in ABS HU/CM internal ground circuit ). (See ABS HU/CM REMOVAL/INSTALLATION.)
No | Go to the next step.
6 | INSPECT BATTERY • Inspect the battery. (See BATTERY INSPECTION [L8, LF].) • Is there any malfunction? | Yes | Inspect the charging system. (See GENERATOR INSPECTION [L8, LF].) Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
7 | INSPECT CHARGING SYSTEM • Start the engine. • Measure the battery voltage with the electrical load (A/C, headlight, etc.) on and the engine idling. • Is the voltage normal? | Yes | Go to the next step.
No | Inspect the charging system (drive belt tension, generator, etc.). (See GENERATOR INSPECTION [L8, LF].) Repair or replace the malfunctioning part according to the inspection results.
*8 | INSPECT ABS HU/CM POWER SUPPLY CIRCUIT FOR CONTINUITY • Turn the ignition switch off. • Disconnect the ABS HU/CM connector. • Turn the ignition switch to the ON position (engine off). • Measure the voltage at ABS HU/CM terminal Z (wiring harness-side). • Is the voltage approx. 12 V? | Yes | Go to the next step.
No | Inspect the ABS HU/CM connector for loose. Reconnect the ABS HU/CM connector properly, if necessary.
*9 | INSPECT ABS HU/CM GROUND CIRCUIT FOR CONTINUITY • Turn the ignition switch off. • Inspect for continuity between ABS HU/CM terminal D (wiring harness-side) and body ground. • Is there continuity? | 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: • Symptom troubleshooting is completed.
No | Repair or replace the wiring harness for a possible open circuit.
*10 | INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR CONTINUITY • Turn the ignition switch off. • Inspect for continuity between ABS HU/CM terminal Y, Z and DLC-2 (wiring harness-side). • Is there continuity? | Yes | Go to the next step.
No | Repair or replace the wiring harness for a possible open circuit.
*11 | INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR SHORT TO POWER SUPPLY • Turn the ignition switch to the ON position (engine off). • Measure the voltage at ABS HU/CM terminal Y, Z (wiring harness-side). • Is the voltage approx. 12 V? | Yes | Repair or replace the wiring harness for a possible short to power supply.
No | Go to the next step.
*12 | INSPECT WIRING HARNESS BETWEEN ABS HU/CM AND DLC‐2 FOR SHORT TO GROUND • Turn the ignition switch off. • Inspect for continuity between ABS HU/CM terminal Y, Z (wiring harness-side) and body ground. • Is there continuity? | Yes | Repair or replace the wiring harness for a possible short to ground.
No | Replace the ABS HU/CM (ABS HU/CM internal communication circuit malfunction). (See ABS HU/CM REMOVAL/INSTALLATION.)

• When performing an asterisked (*) troubleshooting inspection, slightly shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, verify that the connectors, terminals and wiring harness are connected correctly and undamaged.