Page 369 of 4323

A19288
A/F Relay
A23659
Wire Harness Side:
HT
A38
Sensor 1A/F Sensor Connector
AF+
Front ViewAF±
+B A39
B17415
E7ECM Connector
HA1A
A1A+
A1A±
A2A+
A2A±HA2A
± DIAGNOSTICSENGINE
DI±175
369 Author: Date:
2005 SEQUOIA (RM1146U)
12 Check A/F relay.
PREPARATION:
Remove the A/F relay from the engine room J/B.
CHECK:
Inspect the A/F relay.
OK:
Standard:
Terminal No.ConditionSpecified Condition
3 ± 5Always10 KW or higher
3 ± 5Apply B+ between
terminals 1 and 2Below 1 W
NG Replace A/F relay.
OK
13 Check for open and short in harness and connector between ECM and A/F sen-
sor.
PREPARATION:
(a) Disconnect the A38 or A39 A/F sensor connector.
(b) Turn the ignition switch to ON.
CHECK:
(a) Measure the voltage between the +B terminal of the A/F
sensor connector and body ground.
OK:
Standard:
Tester ConnectionsSpecified Conditions
+B (2) ± Body ground9 to 14 V
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the E7 ECM connector.
CHECK:
(a) Check the resistance.
OK:
Standard (Check for open):
Tester ConnectionsSpecified Conditions
HT (A38±1) ± HA1A (E7±2)
HT (A39±1) ± HA2A (E7±1)Below 1 W
AF+ (A38±3) ± A1A+ (E7±22)
AF+ (A39±3) ± A2A+ (E7±23)Below 1 W
AF± (A38±4) ± A1A± (E7±30)
AF± (A39±4) ± A2A± (E7±31)Below 1 W
Page 370 of 4323
A23512
Reference (Bank 1 Sensor 1 System Drawing):
A/F Sensor A/F Relay
Heater
Sensor
A1A+ HA1A
Duty
Control ECM
From
Battery
A/F Heater
Fuse
A1A±
To EFI Relay
DI±176
± DIAGNOSTICSENGINE
370 Author: Date:
2005 SEQUOIA (RM1146U)
Standard (Check for short):
Tester ConnectionsSpecified Conditions
HT (A38±1) or HA1A (E7±2) ± Body ground
HT (A39±1) or HA2A (E7±1) ± Body ground10 kW or higher
AF+ (A38±3) or A1A+ (E7±22) ± Body ground
AF+ (A39±3) or A2A+ (E7±23) ± Body ground10 kW or higher
AF± (A38±4) or A1A± (E7±30) ± Body ground
AF± (A39±4) or A2A± (E7±31) ± Body ground10 kW or higher
NG Replace or replace harness or connector.
OK
14 Replace air fuel ratio sensor.
NEXT
Page 373 of 4323

A21043
Starter Relay EFI Relay
Circuit Opening
Relay
Fuel Pump RelayMREL
FPRTr2
Tr1 EFI No.1
IGNECM
FC
NE Fuel Pump
Battery
StarterFuel Pump Resistor
AM2Ignition Switch
STA
Crankshaft Position
Sensor (NE Signal)
± DIAGNOSTICSENGINE
DI±179
373 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0230 Fuel Pump Primary Circuit
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows from terminal STAR of the ECM to the starter
relay coil and also current flows to terminal STA of the ECM (STA signal).
When the STA signal and NE signal are input to the ECM, the Tr1 is turned ON, current flows to the coil of
the circuit opening relay, the relay switches on, power is supplied to the fuel pump, and the fuel pump oper-
ates.
While the NE signal is generated (engine running), the ECM keeps the Tr1 ON (circuit opening relay ON)
and the fuel pump also keeps operating.
The fuel pump speed is controlled at two levels (high speed or low speed) by the condition of the engine
(starting, light load, heavy load). When the engine starts (STA ON), the Tr2 in the ECM is OFF, so the fuel
pump relay closes and battery positive voltage is applied directly to the fuel pump. The fuel pump operates
at high speed.
After the engine starts while idling or light loads, since the Tr2 goes ON, power is supplied to the fuel pump
via the fuel pump resistor. The fuel pump operates at low speed.
DICEW±02
Page 378 of 4323

DI±184
± DIAGNOSTICSENGINE
378 Author: Date:
2005 SEQUOIA (RM1146U)
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
Page 379 of 4323

A20646
20 V
/Division Injector Signal Waveform
20 V
/Division
GND
100 msec./Division (Idling)(Magnification)
GND
1 msec./Division (Idling)
Injection duration
± DIAGNOSTICSENGINE
DI±185
379 Author: Date:
2005 SEQUOIA (RM1146U)DTC No.
DTC Detecting ConditionTrouble Area
P0300Misfiring 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.
Page 380 of 4323

Crankshaft position sensor
(36±2 teeth or 12 teeth) Camshaft position sensor
ECM
A20490
DI±186
± DIAGNOSTICSENGINE
380 Author: Date:
2005 SEQUOIA (RM1146U)
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 ºpercentage of misfire causing catalyst
damageº is reached 1 time.
Within 200 engine revolutions at a normal rpm, the threshold for ºpercentage of misfire causing catalyst
damageº is reached 3 time.
MONITOR STRATEGY
P0300Random/Multiple cylinder misfire detected
P0301Cylinder 1 misfire detected
P0302Cylinder 2 misfire detected
P0303Cylinder 3 misfire detected
Related DTCsP0304Cylinder 4 misfire detectedRelated DTCs
P0305Cylinder 5 misfire detected
P0306Cylinder 6 misfire detected
P0307Cylinder 7 misfire detected
P0308Cylinder 8 misfire detected
Rid / t
Main sensors/componentsCamshaft position sensor, Crankshaft position
sensor
Required sensors/components
Related sensors/componentsEngine coolant temperature sensor, Intake air
temperature sensor, Throttle position sensor
Frequency of operationContinuous
DurationEvery 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 operation2 driving cycles MIL ON
Immediate MIL blinking (Catalyst deteriorating misfire)
Sequence of operationNone
Page 397 of 4323

S01196S01699
30
20
10
5
3
02040 0.11
0.3
0.2 0.52
60 80 100 ±20
(±4) (104) (140) (176)(32) (68) (212)
A21042
Ohmmeter
Acceptable
TEMPERATURE C (F)
RESISTANCE KW
± DIAGNOSTICSENGINE
DI±203
397 Author: Date:
2005 SEQUOIA (RM1146U)
18 Check engine coolant temperature sensor.
PREPARATION:
Remove the engine coolant temperature sensor.
CHECK:
Measure the resistance between the terminals of the engine
coolant temperature sensor.
Resistance:
Tester ConnectionSpecified Condition
1 ± 22.32 to 2.59 kW (20C (68F))
1 ± 20.310 to 0.326 kW (80C (176F))
NOTICE:
In case of checking the engine coolant temperature sensor
in the water, be careful not to allow water to go into the ter-
minals. After checking, dry the sensor.
HINT:
Alternate procedure: Connect an ohmmeter to the installed en-
gine coolant temperature sensor and read the resistance. Use
an infrared thermometer to measure the engine temperature in
the immediate vicinity of the sensor. Compare these values to
the resistance/temperature graph. Change the engine temper-
ature (by warming up or cooling down) and repeat the test.
NG Replace
engine coolant temperature sensor.
OK
19 Switch step by number of misfire cylinder (Refer to the result of step 4).
High misfire rate cylinderProceed to
1 or 2 cylindersA
More than 3 cylindersB
B Go to step 5.
A
Check for intermittent problems
(See page DI±11).
Page 398 of 4323

DI±204
± DIAGNOSTICSENGINE
398 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0325 Knock Sensor 1 Circuit (Bank 1 or Single
Sensor)
DTC P0327 Knock Sensor 1 Circuit Low Input (Bank 1 or
Single Sensor)
DTC P0328 Knock Sensor 1 Circuit High Input (Bank 1
or Single Sensor)
DTC P0330 Knock Sensor 2 Circuit (Bank 2)
DTC P0332 Knock Sensor 2 Circuit Low Input (Bank 2)
DTC P0333 Knock Sensor 2 Circuit High Input (Bank 2)
CIRCUIT DESCRIPTION
A flat type knock sensor (non±resonant type) has the structure that can detect the vibration in a wider band
of frequency from about 6 kHz to 15 kHz and has the following features.
Knock sensors are fitted on the right bank and left bank of the cylinder block to detect engine knocking.
Each knock sensor contains a piezoelectric element which generates voltage when it becomes deformed.
Generation of the voltage occurs when the cylinder block vibrates due to knocking. If engine knocking oc-
curs, the ignition timing is retarded in order to suppress the knocking.
DTC No.DTC Detection ConditionTrouble Area
P0325
P0330Knock sensor signal level remains at low
(1 trip detection logic)Knock sensor 1 or 2
Knock sensor 1 or 2 (looseness)
ECM
P0327
P0332Output voltage of the knock sensor 1 or 2 is 0.5 V or less
(1 trip detection logic)Short in knock sensor 1 or 2 circuit
Knock sensor 1 or 2
ECM
P0328
P0333Output voltage of the knock sensor 1 or 2 is 4.5 V or more
(1 trip detection logic)Open in knock sensor 1 or 2 circuit
Knock sensor 1 or 2
ECM
DIDFS±01