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 371 of 4323

B17397
Vehicle Speed
Between
38 mph and 75 mph
(60 km/h and 120 km/h)
Idling
Ignition Switch OFF
3 to 5 minutes
Time 2 minutes
(a), (b), (c)(e)
(d)
± DIAGNOSTICSENGINE
DI±177
371 Author: Date:
2005 SEQUOIA (RM1146U)
15 Perform confirmation driving pattern.
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch to ON and turn the tester ON.
(c) Clear DTCs (see page DI±43).
(d) Switch the ECM from normal mode to check mode using the tester (see page DI±44).
(e) Start the engine and warm it up with all the accessories switched OFF.
(f) Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) and at an engine speed of
between 1,400 rpm and 3,200 rpm for 3 to 5 minutes.
HINT:
If the system is still malfunctioning, the MIL will be illuminated during step (e).
NOTICE:
If the conditions in this test are not strictly followed, no malfunction will be detected.
NEXT
16 Check whether DTC output recurs (DTC P0171, P0172, P0174 or P0175)
CHECK:
(a) On the hand±held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / PENDING CODES.
(b) Read DTCs.
RESULT:
Display (DTC Output)Proceed To
P0171, P0172, P0174 or P0175A
No outputB
B Go to step 5.
A
Page 372 of 4323
DI±178
± DIAGNOSTICSENGINE
372 Author: Date:
2005 SEQUOIA (RM1146U)
END
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 374 of 4323
DI±180
± DIAGNOSTICSENGINE
374 Author: Date:
2005 SEQUOIA (RM1146U)DTC No.
DTC Detecting ConditionTrouble Area
P0230Open or short in fuel pump relay circuit
Open or short in fuel pump relay circuit
Fuel pump relay
Circuit opening relay
Fuel pump
ECM
Page 375 of 4323
A23553
G±R
1 28
A 6
BECM
AM2
W±B6
32
15 3
2 121
3 2B IA1
J5
J/CL±O
I18
Ignition SW
3
7
F10
Fusible Link BlockB±R
BI530
10 26 4
12
2
114
68
1 41
5 3L±B
AM2
52HE6
2D
2F 1J1C2F
IA4
E4
E4 IG4
IA4 2H
2H 2C 1C
1JFPR
FC
MREL B±O5
J44
J45J/C E
L
BB1G±RG±REngine Room J/B
4
2F
5V V V
IL2
25
G±O G±O
B
IG2
W±B
W±BA
ED 5 4G±RIG1
B±WB±W
Instrument Panel J/B
F9
Fuel Pump
Resister
Battery2C
W±R W±R5
6
EFI No.15
C/OPN Relay Fuel Pump
Relay
EFI Relay F19
Fuel Pump
± DIAGNOSTICSENGINE
DI±181
375 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
HINT:
This diagnostic chart is based on premise that engine is started. If the engine is not started, proceed to prob-
lem symptoms table on DI±33.
Page 376 of 4323

B17411
E6E1
FPR
A21024
DI±182
± DIAGNOSTICSENGINE
376 Author: Date:
2005 SEQUOIA (RM1146U)
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand-held tester. Freeze frame data records the engine conditions when
a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was
running or stopped, if the engine was warmed up or not, if the air±fuel ratio was lean or rich, as well as other
data from the time when a malfunction occurred.
1 Check voltage between terminal FPR and E1 of ECM.
CHECK:
Measure the voltage between terminals of E6 and E6 ECM con-
nectors.
OK:
Tester ConnectionConditionSpecified Condition
FPR (E6±30) ± E1 (E6±1)STA signal ON9 to 14 V
FPR (E6±30) ± E1 (E6±1)STA signal OFF0 to 3 V
OK Replace ECM (See page SF±80).
NG
2 Check fuel pump relay.
PREPARATION:
Remove the fuel pump relay from the engine room R/B.
CHECK:
Inspect the fuel pump relay.
OK:
Terminal No.ConditionSpecified Condition
3 ± 4Apply B+ between
terminals 1 and 210 KW or higher
3 ± 4AlwaysBelow 1 W
3 ± 5Always10 KW or higher
3 ± 5Apply B+ between
terminals 1 and 2Below 1 W
NG Replace fuel pump relay.
OK