ASCD Brake Switch

DTC P1572 ASCD BRAKE SWITCH





Component Description





When the brake pedal is depressed, ASCD brake switch (2) is turned OFF and stop lamp switch (1) is turned ON. ECM detects the state of the brake pedal by two kinds of input (ON/OFF signal). Refer to System Description for the ASCD function.




CONSULT-III Reference Value in Data Monitor Mode
Specification data are reference values.









On Board Diagnosis Logic
This self-diagnosis has the one trip detection logic.
The MIL will not illuminate for this diagnosis.

NOTE:
- If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer to P0605.
- This self-diagnosis has the one trip detection logic. When malfunction A is detected, DTC is not stored in ECM memory. And in that case, 1st trip DTC and 1st trip freeze frame data are displayed.
1st trip DTC is erased when ignition switch is turned OFF. And even when malfunction A is detected in two consecutive trips, DTC is not stored in ECM memory.

On Board Diagnosis Logic:

DTC Confirmation Procedure

CAUTION:
Always drive vehicle at a safe speed.

NOTE:
- Procedure for malfunction B is not described here. It takes extremely long time to complete procedure for malfunction B. By performing procedure for malfunction A, the incident that causes malfunction B can be detected.
- If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
Steps 4 to 6 may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road test is expected to be easier, it is unnecessary to lift the vehicle.
1. Start engine (VDC switch OFF).
2. Press MAIN switch and check that CRUISE lamp illuminate.
3. Drive the vehicle for at least 5 consecutive seconds under the following conditions.





4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to ASCD Brake Switch.
If 1st trip DTC is not detected, go to the following step.
6. Drive the vehicle for at least 5 consecutive seconds under the following conditions.





7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to ASCD Brake Switch.




Wiring Diagram
Specification data are reference values and are measured between each terminal and ground.

CAUTION:
Never use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.









Diagnosis Procedure
1.CHECK OVERALL FUNCTION-I
With CONSULT-III
1. Turn ignition switch ON.
2. Select "BRAKE SW1" in "DATA MONITOR" mode with CONSULT-III.
3. Check "BRAKE SW1" indication under the following conditions.





Without CONSULT-III
1. Turn ignition switch ON.





2. Check voltage between ECM terminal 108 and ground under the following conditions.





OK or NG
OK - GO TO 2.
NG - GO TO 3.
2.CHECK OVERALL FUNCTION-II
With CONSULT-III
Check "BRAKE SW2" indication in "DATA MONITOR" mode.





Without CONSULT-III
Check voltage between ECM terminal 101 and ground under the following conditions.










OK or NG
OK - GO TO 13.
NG - GO TO 8.
3.CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.





2. Disconnect ASCD brake switch (2) harness connector.
- Stop lamp switch (1)
3. Turn ignition switch ON.





4. Check voltage between ASCD brake switch terminal 1 and ground with CONSULT-III or tester.

Voltage: Battery voltage

OK or NG
OK - GO TO 5.
NG - GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
- Fuse block (J/B) connector E102
- 10 A fuse
- Harness for open or short between ASCD brake switch and fuse
Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK ASCD BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 108 and ASCD brake switch terminal 2. Refer to Wiring Diagram.

Continuity should exist.

4. Also check harness for short to ground and short to power.
OK or NG
OK - GO TO 7.
NG - GO TO 6.
6.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E108, M15
- Harness for open or short between ECM and ASCD brake switch
Repair open circuit or short to ground or short to power in harness or connectors.
7.CHECK ASCD BRAKE SWITCH
Refer to ASCD Brake Switch
OK or NG
OK - GO TO 13.
NG - Replace ASCD brake switch.
8.CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.





2. Disconnect stop lamp switch (1) harness connector.
- ASCD brake switch (2)





3. Check voltage between stop lamp switch terminal 1 and ground with CONSULT -III or tester.

Voltage: Battery voltage

OK or NG
OK - GO TO 10.
NG - GO TO 9.
9.DETECT MALFUNCTIONING PART
Check the following.
- Fuse block (J/B) connector E101
- 10 A fuse
- Harness for open or short between stop lamp switch and battery
Repair open circuit or short to ground or short to power in harness or connectors.
10.CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 101 and stop lamp switch terminal 2. Refer to Wiring Diagram.

Continuity should exist.

3. Also check harness for short to ground and short to power.
OK or NG
OK - GO TO 12.
NG - GO TO 11.
11.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E108, M15
- Harness for open or short between ECM and stop lamp switch
Repair open circuit or short to ground or short to power in harness or connectors.
12.CHECK STOP LAMP SWITCH
Refer to ASCD Brake Switch
OK or NG
OK - GO TO 13.
NG - Replace stop lamp switch.
13.CHECK INTERMITTENT INCIDENT
Refer to Diagnosis Procedure.
INSPECTION END




Component Inspection

ASCD BRAKE SWITCH
1. Turn ignition switch OFF.
2. Disconnect ASCD brake switch harness connector.





3. Check continuity between ASCD brake switch terminals 1 and 2 under the following conditions.





4. If NG, adjust ASCD brake switch installation, refer to Procedures, and perform step 3 again.

STOP LAMP SWITCH
1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.





3. Check continuity between stop lamp switch terminals 1 and 2 under the following conditions.





4. If NG, adjust stop lamp switch installation, refer to Procedures, and perform step 3 again.