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 SDT.
4) Check 1st trip DTC.
5) If 1st trip DTC is detected, go to "Diagnosis Procedure".

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 SDT or tester.











OK or NG
OK
GO TO 4.
NG
GO TO 3.

3. DETECT MALFUNCTIONING PART

Check the following.
- 10 A fuse (No.20)
- 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.






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

Refer to "Component Inspection".

OK or NG
OK
GO TO 6.
NG
Replace stop lamp switch. Refer to [Brake Pedal: Exploded View] Brake Pedal Exploded View.

6. CHECK INTERMITTENT INCIDENT

Refer to [Service Information for Electrical Incident: Intermittent Incident] Service Information for Electrical 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, refer to [Brake Pedal: Inspection and Adjustment] Adjustments , and perform step 2 again.