Toyota Tundra. Manual — part 1362

Fig. 103: Identifying R7 Fuel Pump ECU & A24 ECM Connectors

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : Go To Next Step

12. REPLACE FUEL PUMP ECU

a. Replace the fuel pump ECU. (See FUEL PUMP ).

13. CONFIRM WHETHER DTC OUTPUT RECURS

a. Check that there is 17 Liters (18 US qts, 15 lmp. qts) or more of fuel remaining.

b. Connect the Techstream to the DLC3.

c. Turn the ignition switch to ON.

d. Turn the Techstream ON.

e. Clear DTCs. (See DTC CHECK/CLEAR ).

f. Cranking it for 15 seconds.

g. Idle it for 1 minute.

h. Enter the following menus: Powertrain/Engine and ECT/Trouble Codes.

i. Read the DTCs.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Result

RESULT REFERENCE

B : REPLACE ECM (See REMOVAL )

A : END

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

INTEGRATION RELAY)

a. Remove the circuit opening relay (C/OPN) from the engine room relay block.

b. Remove the IGN fuse from the engine room relay block.

c. Remove the integration relay from the engine room relay block.

d. Disconnect the 1B integration relay connector.

e. Measure the resistance according to the value (s) in the table below.

Standard resistance

STANDARD RESISTANCE SPECIFICATION

Result

Proceed To

No DTC is output

A

DTC P0230 is output

B

Tester Connection

Condition Specified Condition

C/OPN relay (2) - IGN fuse (2)

Always

Below 1 ohms

C/OPN relay (5) - 1B-4

Always

Below 1 ohms

C/OPN relay (2) or IGN fuse (2) - Body ground Always

10 kohms or higher

C/OPN relay (5) or 1B-4 - Body ground

Always

10 kohms or higher

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 104: Identifying Relay (C/OPN) & Integration Relay

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : GO TO ECM POWER SOURCE CIRCUIT

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

DESCRIPTION

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 105: ECM & CKP Sensor Connection Diagram

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high HC
concentration levels can cause increases in exhaust emission levels. High concentrations of HC can also cause
increases in the Three-Way Catalytic Converter (TWC) temperature, which may cause damage to the TWC. To
prevent these increases in emissions and to limit the possibility of thermal damage, the ECM monitors the
misfire rate. When the temperature of the TWC reaches the point of thermal degradation, the ECM blinks the
MIL. To monitor misfires, the ECM uses both the Camshaft Position (CMP) sensor and the Crankshaft Position
(CKP) sensor. The CMP sensor is used to identify any misfiring cylinders and the CKP sensor is used to
measure variations in the crankshaft rotation speed. Misfires are counted as when the crankshaft rotation speed
variations exceed predetermined thresholds.

If the misfire rate exceeds the threshold level, the ECM illuminates the MIL and sets a DTC.

DTC DETECTION CONDITION AND TROUBLE AREA

DTC

Code

DTC Detection Condition

Trouble Area

P0300

Simultaneous misfiring of several cylinders occurs and one of
following conditions below is detected (2 trip detection logic):



High temperature misfire occurs in Three-Way Catalytic
Converter (TWC) (MIL blinks)



Emission deterioration misfire occurs (MIL illuminates)



Open or short in engine
wire harness



Connector connection



Vacuum hose
connections



Ignition system



Injector



Fuel pressure



Mass Air Flow (MAF)
meter



Engine Coolant
Temperature (ECT)
sensor



Compression pressure



Valve clearance



Valve timing



PCV valve and hose

P0301
P0302
P0303
P0304
P0305
P0306
P0307

Misfiring of specific cylinder occurs and one of following
conditions below is detected (2 trip detection logic):



High temperature misfire occurs in Three-Way Catalytic
Converter (TWC) (MIL blinks)



Emission deterioration misfire occurs (MIL illuminates)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra