Nissan Titan. Manual - part 279

P1805 BRAKE SWITCH

EC-417

< DTC/CIRCUIT DIAGNOSIS >

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P1805 BRAKE SWITCH

Description

INFOID:0000000009886862

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

INFOID:0000000009886863

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

INFOID:0000000009886864

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

EC-417, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000009886865

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 

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1805
1805

Brake switch

A brake switch signal is not sent to ECM for ex-
tremely long time while the vehicle is driving.

• Harness or connectors

(Stop lamp switch circuit is open or short-
ed.)

• Stop lamp switch

Engine operating condition in fail-safe mode

ECM controls the electric throttle control actuator by regulating the throttle opening to a small range.
Therefore, acceleration will be poor.

Vehicle condition

Driving condition

When engine is idling

Normal

When accelerating

Poor acceleration

Brake pedal

Stop lamp

Fully released

Not illuminated

Depressed

Illuminated

EC-418

< DTC/CIRCUIT DIAGNOSIS >

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P1805 BRAKE SWITCH

1. Disconnect stop lamp switch harness connector.

2. Check voltage between stop lamp switch terminal 1 and ground

with CONSULT or tester.

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

• 10A fuse

• Harness for open and short between stop lamp switch and fuse

>> 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 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 

EC-419, "Component Inspection"

.

OK or NG

OK

>> GO TO 6.

NG

>> Replace stop lamp switch.

6.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-39, "How to Check Terminal"

 and 

GI-42, "Intermittent Incident"

.

>> INSPECTION END

BBIA0373E

Voltage: Battery voltage

WBIA0545E

Continuity should exist.

P1805 BRAKE SWITCH

EC-419

< DTC/CIRCUIT DIAGNOSIS >

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Component Inspection

INFOID:0000000009886866

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 

BR-13,

"Inspection and Adjustment - Standard Pedal"

, and perform step

2 again.

BBIA0373E

Conditions

Continuity

Brake pedal: Fully released

Should not exist.

Brake pedal: Slightly depressed

Should exist.

WBIA0546E

EC-420

< DTC/CIRCUIT DIAGNOSIS >

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P2096, P2097, P2098, P2099 A/F SENSOR 1

P2096, P2097, P2098, P2099 A/F SENSOR 1

Component Description

INFOID:0000000009886905

The air fuel ratio (A/F) sensor 1 is a planar one-cell limit current sen-

sor. The sensor element of the A/F sensor 1 is composed an elec-

trode layer, which transports ions. It has a heater in the element.
The sensor is capable of precise measurement   = 1, but also in the

lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide   range.

The exhaust gas components diffuse through the diffusion layer at

the sensor cell. An electrode layer is applied voltage, and this current

relative oxygen density in lean. Also this current relative hydrocar-

bon density in rich.

Therefore, the A/F sensor 1 is able to indicate air fuel ratio by this

electrode layer of current. In addition, a heater is integrated in the

sensor to ensure the required operating temperature of about 800

°C

(1,472

°F).

On Board Diagnosis Logic

INFOID:0000000009886906

DTC Confirmation Procedure

INFOID:0000000009886907

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-

ing the next step. 
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:

PBIB3353E

JPBIA5446GB

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible Cause

P2096

POST CAT FUEL TRIM SYS 
B1
(Post catalyst fuel trim system 
too lean bank 1)

The output voltage computed by ECM from the A/
F sensor 1 signal is shifts to the lean side for a 
specified period.

• A/F sensor 1 (bank 1)
• A/F sensor 1 heater
• Heated oxygen sensor 2 (bank 1)
• Fuel pressure
• Fuel injector
• Intake air leaks
• Exhaust gas leaks

P2097

POST CAT FUEL TRIM SYS 
B1
(Post catalyst fuel trim system 
too rich bank 1)

The A/F signal computed by ECM from the A/F 
sensor 1 signal is shifts to the rich side for a spec-
ified period.

P2098

POST CAT FUEL TRIM SYS 
B2
(Post catalyst fuel trim system 
too lean bank 2)

The output voltage computed by ECM from the A/
F sensor 1 signal is shifts to the lean side for a 
specified period.

• A/F sensor 1 (bank 2)
• A/F sensor 1 heater
• Heated oxygen sensor 2 (bank 2)
• Fuel pressure
• Fuel injector
• Intake air leaks
• Exhaust gas leaks

P2099

POST CAT FUEL TRIM SYS 
B2
(Post catalyst fuel trim system 
too rich bank 2)

The A/F signal computed by ECM from the A/F 
sensor 1 signal is shifts to the rich side for a spec-
ified period.