Engine Controls

P1572 ASCD BRAKE SWITCH





Component Description





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




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

NOTE:
- If DTC P 1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. 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 OFF. And even when malfunction A is detected in two consecutive trips, DTC is not stored in ECM memory.









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 step.
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 3 and 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 make sure that CRUISE indicator lights up.
3. Drive the vehicle for at least 5 consecutive seconds under the following condition.





4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to Engine Controls.
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 condition.





7. Check 1st trip DTC.
8. If 1st trip DTC is detected, go to Engine Controls.




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 11.
NG - GO TO 7.
3.CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.





2. Disconnect ASCD brake switch harness connector.
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.
- Harness connectors M31, E152
- Fuse block (J/B) connector M4
- 10 A fuse (No. 15)
- 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 6.
NG - Repair open circuit or short to ground or short to power in harness or connectors.
6.CHECK ASCD BRAKE SWITCH
Engine Controls.
OK or NG
OK - GO TO 11.
NG - Replace ASCD brake switch.
7.CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.





2. Disconnect stop lamp switch harness connector.





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

Voltage: Battery voltage

OK or NG
OK - GO TO 9.
NG - GO TO 8.
8.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors M31, E152
- Fuse block (J/B) connector M60
- 10 A fuse (No. 20)
- 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.
9.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 4. 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 10.
NG - Repair open circuit or short to ground or short to power in harness or connectors.
10.CHECK STOP LAMP SWITCH
Engine Controls.
OK or NG
OK - GO TO 11.
NG - Replace stop lamp switch.
11.CHECK INTERMITTENT INCIDENT
How to Check Terminal and Intermittent Incident.
- INSPECTION END




Component Inspection

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





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





If NG, adjust ASCD brake switch installation, Inspection and Adjustment, and perform step 3 again.

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





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





If NG, adjust stop lamp switch installation, Inspection and Adjustment, and perform step 3 again.