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 being driven.




On Board Diagnosis Logic
The MIL will not illuminate for this diagnosis.






FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode.









DTC Confirmation Procedure

NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.
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 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 harness connector.





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.
- 10A fuse
- Fuse block (J/B) connector E160
- 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 ECM harness connector.





2. Disconnect stop lamp switch harness connector.
3. Check harness continuity between ECM terminal 101 and stop lamp 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 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
Intermittent Incident.
- INSPECTION END




Component Inspection

STOP LAMP SWITCH





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










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