Toyota Sequoia (2005). Manual - part 95

A21377

Engine Room J/B:

Fuel Pump 
Relay

B17414

E6

ECM Connector

FPR

–

DIAGNOSTICS

ENGINE

DI–183

377

3

Check for open and short in harness and connector between fuel pump relay
and ECM.

PREPARATION:
(a)

Remove the fuel pump relay from the engine room J/B.

(b)

Disconnect the E6 ECM connector.

CHECK:
Measure the resistance between wire harness side connectors.
OK:

Standard:

Tester Connection

Specified Condition

Engine Room J/B (Fuel pump relay ter-

minal 1) – FPR (E6–30)

Below 1 

Ω

Engine Room J/B (Fuel pump relay ter-

minal 1) or FPR (E6–30) – 

Body ground

10 k

Ω

 or higher

NG

Repair or replace harness or connector.

OK

Replace ECM (See page 

SF–80

).

DI–184

–

DIAGNOSTICS

ENGINE

378

DTC

P0300

Random/Multiple Cylinder Misfire Detected

DTC

P0301

Cylinder 1 Misfire Detected

DTC

P0302

Cylinder 2 Misfire Detected

DTC

P0303

Cylinder 3 Misfire Detected

DTC

P0304

Cylinder 4 Misfire Detected

DTC

P0305

Cylinder 5 Misfire Detected

DTC

P0306

Cylinder 6 Misfire Detected

DTC

P0307

Cylinder 7 Misfire Detected

DTC

P0308

Cylinder 8 Misfire Detected

CIRCUIT DESCRIPTION

When a misfire occurs in the engine, hydrocarbons (HC) enter the exhaust in high concentrations. If this HC
concentration is high enough, there could be an increase in exhaust emission levels. High concentrations
of HC can also cause the temperature of the catalyst to increase, possibly damaging the catalyst. To prevent
this increase in emissions and limit the possibility of thermal damage, the ECM monitors the misfire rate.
When the temperature of the catalyst reaches a point of thermal degradation, the ECM will blink the MIL.
For monitoring misfire, the ECM uses both the camshaft position sensor and the crankshaft position sensor.
The camshaft position sensor is used to identify misfiring cylinders and the crankshaft position sensor is used
to measure variations in the crankshaft rotation speed. The misfire counter increments when crankshaft rota-
tion speed variations exceed threshold values. 
If the misfiring rate exceeds the threshold value, which could cause emissions deterioration, the ECM illumi-
nates the MIL.

DID85–01

A20646

20 V
/Division

Injector Signal Waveform

20 V
/Division

GND

100 msec./Division (Idling)

(Magnification)

GND

1 msec./Division (Idling)

Injection duration

–

DIAGNOSTICS

ENGINE

DI–185

379

DTC No.

DTC Detecting Condition

Trouble Area

P0300

Misfiring of random cylinders is detected

Open or short in engine wire

Connector connection

Vacuum hose connection

P0301

P0302

P0303

P0304

P0305

P0306

P0307

P0308

Misfiring of each cylinder is detected

Vacuum hose connection

Ignition system

Injector

Fuel pressure

Mass air flow meter

Engine coolant temperature sensor

Compression pressure

Valve clearance

Valve timing

PCV piping

ECM

HINT:
When several codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded,
it indicates that the misfires have been detected and recorded at different times.
Reference: Inspection using the oscilloscope. 
With the engine idling, check the waveform between terminals #1 to #8 and E01 of the ECM connectors.
HINT:
The correct waveform is as shown in the illustration.

Crankshaft position sensor 
(36–2 teeth or 12 teeth)

Camshaft position sensor

ECM

A20490

DI–186

–

DIAGNOSTICS

ENGINE

380

MONITOR DESCRIPTION

The ECM illuminates the MIL (2 trip detection logic) if:
The ECM will illuminate the MIL when the percentage of misfire exceeds the specified limit per 1,000 engine
revolutions. One occurrence of excessive misfire during engine start will set the MIL. Four occurrences are
required to set the MIL 1,000 revolutions after engine start.
The ECM blinks the MIL (the MIL blinks immediately) if:

Within 200 engine revolutions at a high rpm, the threshold for ”percentage of misfire causing catalyst
damage” is reached 1 time.

Within 200 engine revolutions at a normal rpm, the threshold for ”percentage of misfire causing catalyst
damage” is reached 3 time.

MONITOR STRATEGY

P0300

Random/Multiple cylinder misfire detected

P0301

Cylinder 1 misfire detected

P0302

Cylinder 2 misfire detected

P0303

Cylinder 3 misfire detected

Related DTCs

P0304

Cylinder 4 misfire detected

Related DTCs

P0305

Cylinder 5 misfire detected

P0306

Cylinder 6 misfire detected

P0307

Cylinder 7 misfire detected

P0308

Cylinder 8 misfire detected

R

i d

/

t

Main sensors/components

Camshaft position sensor, Crankshaft position
sensor

Required sensors/components

Related sensors/components

Engine coolant temperature sensor, Intake air
temperature sensor, Throttle position sensor

Frequency of operation

Continuous

Duration

Every 1,000 revolutions (soon after engine is started: 1 time, other: 4 times) (emission related misfire)
Every 200 revolutions (1 or 3 times) (catalyst deteriorating misfire)

MIL operation

2 driving cycles MIL ON
Immediate MIL blinking (Catalyst deteriorating misfire)

Sequence of operation

None