Toyota Tundra. Manual — part 1272

Fig. 271: Identifying A24 & D74 ECM Connectors Terminals

n. Reconnect the air switching valve (bank 1).

o. Reconnect the air switching valve (bank 2).

p. Reconnect the VVT sensor (bank 1) connector.

q. Reconnect the VVT sensor (bank 2) connector.

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : REPLACE ECM (See REMOVAL )

FUEL PUMP CONTROL CIRCUIT

DESCRIPTION

The fuel pump circuit consists of the ECM, fuel pump and fuel pump ECU (which operates the fuel pump).
Based on the engine output, the ECM determines the fuel pump speed. The speed is then converted to a duty
signal and sent to the fuel pump ECU. Based on the signal sent from the ECM, the fuel pump ECU adjusts the
fuel pump operation speed between 3 settings.

WIRING DIAGRAM

Proceed to P0230 .

INSPECTION PROCEDURE

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

This troubleshooting procedure is based on the premise that the engine is started. If the engine is not started,
proceed to the problem symptoms table (See PROBLEM SYMPTOMS TABLE ).

1. PERFORM ACTIVE TEST USING TECHSTREAM (FUEL PUMP)

a. Connect the Techstream to the DLC3.

b. Turn the ignition switch ON and turn the Techstream ON.

c. Enter the following menus: Powertrain/Engine and ECT/Active Test/Control the Fuel Pump/Speed.

d. Check whether operating sounds can be heard while operating the relay using the Techstream.

OK: Operating sounds can be heard from relay.

NG : Go to step 4

OK : Go to next step.

2. CHECK HARNESS AND CONNECTOR (FUEL PUMP ECU - ECM, BODY GROUND) (See

INSPECTION PROCEDURE )

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : Go to next step.

3. INSPECT FUEL PUMP ECU (FPC SIGNAL) (See INSPECTION PROCEDURE )

NG : REPLACE ECM (See REMOVAL )

OK : REPLACE FUEL PUMP ECU . (See FUEL PUMP ECU ).

4. INSPECT CIRCUIT OPENING RELAY (C/OPN) (See INSPECTION PROCEDURE )

NG : REPLACE CIRCUIT OPENING RELAY (C/OPN) (See ON-VEHICLE INSPECTION )

OK : Go to next step.

5. INSPECT CIRCUIT OPENING RELAY (POWER SOURCE VOLTAGE) (See INSPECTION

PROCEDURE )

NG : Go to step 11

OK : Go to next step.

6. CHECK HARNESS AND CONNECTOR (CIRCUIT OPENING RELAY (C/OPN) - ECU, FUEL

PUMP ECU) (See INSPECTION PROCEDURE )

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

OK : Go to next step.

7. CHECK HARNESS AND CONNECTOR (FUEL PUMP - FUEL PUMP ECU) (See INSPECTION

PROCEDURE )

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : Go to next step.

8. INSPECT FUEL PUMP

a. Inspect the fuel pump. (See INSPECTION ).

NG : REPLACE FUEL PUMP . (See FUEL PUMP ).

OK : Go to next step.

9. CHECK HARNESS AND CONNECTOR (FUEL PUMP ECU - ECM, BODY GROUND) (See

INSPECTION PROCEDURE )

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : Go to next step.

10. INSPECT FUEL PUMP ECU (FPC SIGNAL) (See INSPECTION PROCEDURE )

NG : REPLACE ECM (See REMOVAL )

OK : REPLACE FUEL PUMP ECU (See FUEL PUMP ECU ).

11. CHECK HARNESS AND CONNECTOR (CIRCUIT OPENING RELAY (C/OPN) - IGN FUSE,

INTEGRATION RELAY) (See INSPECTION PROCEDURE )

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : GO TO ECM POWER SOURCE CIRCUIT

CRANKING HOLDING FUNCTION CIRCUIT

DESCRIPTION

The cranking holding control system provides current to the starter when the ECM detects the ignition switch's
start signal (STSW). When the ECM performs a firing judgment, the system cuts current to the starter. When an
ECM receives the STSW signal, it turns on the ST CUT relay, which prevents flickering of the combination
meter, clock, audio system, etc. Also, the ECM sends a signal to the ECM's STAR terminal. Then the STAR
output signal travels through the park/neutral position (PNP) switch to the ST relay, causing the starter to
activate.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

When the engine is cranking, the starter operation signal is sent to the ECM's STA terminal.

Fig. 272: Cranking Holding Function Circuit Diagram

WIRING DIAGRAM

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra