NO.6 BRAKE SYSTEM WARNING LIGHT STAYS ON 4 S OR MORE WHEN IGNITION SWITCH TURNED TO ON POSITION [ABS]

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6 | Brake system warning light stays on 4 s or more when ignition switch turned to ON position (Parking brake is released)
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POSSIBLE CAUSE | • Brake fluid amount is low • Improper brake switch signal input to PCM (Vehicle without malfunction warning light, applied VIN (assumed): NC18**215550—, NC18**250831—, NC30**202488—, NCA8**251024—) • ABS HU/CM DTC is stored • Instrument cluster malfunction • Parking brake switch, brake fluid level sensor or in some other part malfunction • Short to ground in wiring harness between the following terminals: ― Instrument cluster terminal 2M and parking brake switch terminal A ― Instrument cluster terminal 1D and brake fluid level sensor terminal A • ABS HU/CM malfunction • 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 BRAKE FLUID LEVEL • Inspect the brake fluid level. • Is the brake fluid level normal? | Yes | Vehicles without malfunction warning light (Applied VIN (assumed): NC18**215550—, NC18**250831—, NC30**202488—, NCA8**251024—) Go to the next step. Others Go to step 3.
No | Add the brake fluid.
2 | CONFIRM PCM DTC • Perform the Reading DTCs Procedure. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) • Is the DTC P0571 and/or P0703 present? | Yes | Go to the applicable DTC inspection. (See DTC P0571 [L8, LF].) (See DTC P0703 [L8, LF].)
No | Go to the next step.
*3 | 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 7.
No | Go to the next step.
4 | 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.
5 | 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.)
6 | VERIFY WHETHER MALFUNCTION IS IN PARKING BRAKE SWITCH OR BRAKE FLUID LEVEL SENSOR, OR IN SOME OTHER PART • Disconnect the connectors in the following order: 1. Parking brake switch connector 2. Brake fluid level sensor connector • Does the brake system warning light go out with ignition switch turned to the ON position? | Yes | Replace the parking brake switch and/or brake fluid level sensor (short with some internal part). (See MASTER CYLINDER REMOVAL/INSTALLATION.) (See PARKING BRAKE LEVER REMOVAL/INSTALLATION.)
No | Inspect the wiring harness between the following terminals for short to ground: • Instrument cluster terminal 2M (brake system warning light) and parking brake switch terminal A • Instrument cluster terminal 1D (brake system warning light) and brake fluid level sensor terminal A If the wiring harness has a malfunction: • Repair or replace the wiring harness for a possible short to ground. If the wiring harness is normal: • Replace the ABS HU/CM. (See ABS HU/CM REMOVAL/INSTALLATION.)
*7 | 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.
*8 | 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.
*9 | 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.