ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P1521 BRAKE SWITCH CIRCUIT RANGE

ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P1521 BRAKE SWITCH CIRCUIT RANGE

DTC DETECTING CONDITION:

Detected when two consecutive driving cycles with fault occur.

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode , and Inspection Mode .

WIRING DIAGRAM:

STEP	CHECK	YES	NO
1.CHECK INPUT SIGNAL OF ECM. 1) Turn the ignition switch to ON. 2) Measure the voltage between ECM and chassis ground with the brake pedal depressed. Connector & terminal (B136) No. 13 (+) — Chassis ground (−):	Is the voltage 10 V or more?	Repair the poor contact of ECM connector.
2.CHECK STOP LIGHT AND BRAKE SWITCH. 1) Turn the ignition switch to OFF. 2) Disconnect the stop light & brake switch connector. 3) Measure the resistance of the stop light & brake switch connectors with the brake pedal depressed. Terminals 4 door model No. 3 — No. 4: 5 door model No. 1 — No. 2:	Is the resistance less than 1 Ω?		Replace the stop light & brake switch.
3.CHECK HARNESS BETWEEN ECM AND STOP LIGHT & BRAKE SWITCH CONNECTOR. 1) Disconnect the connectors from ECM. 2) Measure the resistance of the harness between the ECM and stop light & brake switch connector. Connector & terminal 4 door model (B136) No. 13 — (B65) No. 4: 5 door model (B136) No. 13 — (B65) No. 2:	Is the resistance less than 1 Ω?		Repair the harness and connector. NOTE: In this case, repair the following item: • Open circuit of harness between ECM and stop light & brake switch connector • Poor contact of coupling connector
4.CHECK HARNESS BETWEEN ECM AND STOP LIGHT & BRAKE SWITCH CONNECTOR. Measure the resistance between ECM and chassis ground. Connector & terminal (B136) No. 13 — Chassis ground:	Is the resistance 1 MΩ or more?		NOTE: Check the following item and repair or replace if necessary. • Short circuit to ground in harness between ECM and stop light & brake switch connector • Blown-out of fuse (F/B No. 8)
5.CHECK POWER SUPPLY OF STOP LIGHT AND BRAKE SWITCH. 1) Turn the ignition switch to ON. 2) Measure the voltage between the stop light & brake switch connector and chassis ground. Connector & terminal 4 door model (B65) No. 3 (+) — Chassis ground (−): 5 door model (B65) No. 1 (+) — Chassis ground (−):	Is the voltage 10 V or more?	Repair the poor contact of the stop light & brake switch connector.	NOTE: Check the following item and repair or replace if necessary. • Open circuit of power supply circuit • Ground short circuit of power supply circuit • Blown out of fuse (F/B No. 8)