Toyota Sequoia (2005). Manual — part 94

A21043

Starter Relay

EFI Relay

Circuit Opening
Relay

Fuel Pump Relay

MREL

FPR

Tr2

Tr1

EFI No.1

IGN

ECM

FC

NE

Fuel Pump

Battery

Starter

Fuel Pump Resistor

AM2

Ignition Switch

STA

Crankshaft Position
Sensor (NE Signal)

–

DIAGNOSTICS

ENGINE

DI–179

373

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

DI–180

–

DIAGNOSTICS

ENGINE

374

DTC No.

DTC Detecting Condition

Trouble Area

P0230

Open or short in fuel pump relay circuit

Open or short in fuel pump relay circuit

Fuel pump relay

Circuit opening relay

Fuel pump

ECM

A23553

G–R

1

2

8

A

6

B

ECM

AM2

W–B

6

3

2

1

5

3

2

1

2

1

3

2B

IA1

J5
J/C

L–O

I18
Ignition SW

3

7

F10
Fusible Link Block

B–R

BI

5

30

10

26

4

1

2

2

1

14

6

8

1

4

1

5

3

L–B

AM2

5

2H

E6

2D

2F

1J

1C

2F

IA4

E4

E4

IG4

IA4

2H

2H

2C

1C

1J

FPR

FC

MREL

B–O

5

J44

J45

J/C

E

L

BB1

G–R

G–R

Engine Room J/B

4

2F

5

V

V

V

IL2

25

G–O

G–O

B

IG2

W–B

W–B

A

ED

5

4

G–R

IG1

B–W

B–W

Instrument

Panel J/B

F9
Fuel Pump
Resister

Battery

2C

W–R

W–R

5

6

EFI No.1

5

C/OPN Relay

Fuel Pump
Relay

EFI Relay

F19
Fuel Pump

–

DIAGNOSTICS

ENGINE

DI–181

375

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

.

B17411

E6

E1

FPR

A21024

DI–182

–

DIAGNOSTICS

ENGINE

376

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 Connection

Condition

Specified Condition

FPR (E6–30) – E1 (E6–1)

STA signal ON

9 to 14 V

FPR (E6–30) – E1 (E6–1)

STA signal OFF

0 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.

Condition

Specified Condition

3 – 4

Apply B+ between

terminals 1 and 2

10 K

Ω

or higher

3 – 4

Always

Below 1

Ω

3 – 5

Always

10 K

Ω

or higher

3 – 5

Apply B+ between

terminals 1 and 2

Below 1

Ω

NG

Replace fuel pump relay.

OK