P1805

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.




On Board Diagnosis Logic
The MIL will not light up for this self-diagnosis.






FAIL-SAFE MODE
When the malfunction is detected, the ECM enters 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 with CONSULT-III.
4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to P1805.




Diagnosis Procedure
1.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 6.
NG - GO TO 2.
2.CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT





1. Disconnect stop lamp switch harness connector.





2. Check voltage between stop lamp switch terminal 3 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 M31, E152
- Fuse block (J/B) connector M60
- 10 A fuse (No. 20)
- 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. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 101 and stop lamp switch terminal 4. 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 or connectors.
5.CHECK STOP LAMP SWITCH
P1805.
OK or NG
OK - GO TO 6.
NG - Replace stop lamp switch.
6.CHECK INTERMITTENT INCIDENT
How to Check Terminal and Intermittent Incident.
- INSPECTION END




Component Inspection

STOP LAMP SWITCH





1. Disconnect stop lamp switch harness connector.





2. Check continuity between stop lamp switch terminals 3 and 4 under the following conditions.





3. If NG, adjust stop lamp switch installation, Inspection and Adjustment, and perform step 2 again.