Up to VIn #386333

DTC P1805 BRAKE SWITCH





Description
Brake switch signal is applied to the ECM through the stop lamp switch when the brake pedal is depressed.
This signal is used mainly to decrease the engine speed when the vehicle is driving.




CONSULT-III Reference Value in Data Monitor Mode









On Board Diagnosis Logic






FAIL-SAFE MODE









DTC Confirmation Procedure
1. Turn ignition switch ON.
2. Fully depress the brake pedal for at least 5 seconds.
3. Erase the DTC.
4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to "Diagnosis Procedure".




Wiring Diagram














Diagnosis Procedure
1.CHECK STOP LAMP SWITCH CIRCUIT
1. Turn ignition switch OFF.
2. Check the stop lamp when depressing and releasing the brake pedal.





OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2.CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT





1. Disconnect stop lamp switch (1) harness connector.
- Brake pedal (2)
2. Check voltage between stop lamp switch terminal 1 and ground with CONSULT-III or tester.






Voltage: Battery voltage

OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors M69, E7
- 10A fuse
- Harness for open and short between stop lamp switch and battery
>> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect stop lamp switch (1) harness connector.
2. Disconnect ECM harness connector.
3. Check harness continuity between stop lamp switch terminal 2 and ECM terminal 99. 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 5.
NG >> Repair open circuit or short to ground or short to power in harness connectors.
5.CHECK STOP LAMP SWITCH
Refer to "Component Inspection".
OK or NG
OK >> GO TO 6.
NG >> Replace stop lamp switch.
6.CHECK INTERMITTENT INCIDENT
Refer to Up to VIn #386333 Up to VIn #386333.
>> INSPECTION END




Component Inspection

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.










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