Toyota Tundra. Manual — part 1459

Fig. 314: Identifying D61 Intake Air Control Valve, D74 ECM & 1B Integration Relay
Connectors

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : REPLACE ECM (See REMOVAL )

MIL CIRCUIT

DESCRIPTION

2008 Toyota Tundra

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

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunction detections by the ECM. When
the ignition switch is turned to ON, power is supplied to the MIL circuit, and the ECM provides the circuit
ground which illuminates the MIL.

The MIL operation can be checked visually: When the ignition switch is first turned ON, the MIL should be
illuminated and should then turn off when the engine is started. If the MIL remains illuminated or is not
illuminated, conduct the following troubleshooting procedure using the Techstream.

WIRING DIAGRAM

Fig. 315: Malfunction Indicator Lamp - Wiring Diagram

INSPECTION PROCEDURE

1. CHECK THAT MIL IS ILLUMINATED

a. Perform troubleshooting in accordance with the table below.

Result

RESULT REFERENCE

B : Go to step 5

Result

Proceed To

MIL remains ON

A

MIL does not illuminate

B

2008 Toyota Tundra

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

A : Go to Next Step

2. CHECK WHETHER MIL TURNS OFF

a. Connect the Techstream to the DLC3.

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

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

d. Check if any DTCs have been stored. Note down any DTCs.

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

f. Check if the MIL goes off.

Standard:

MIL goes off.

NG : Go to step 3

OK : REPAIR CIRCUITS INDICATED BY OUTPUT DTCS (See DIAGNOSTIC TROUBLE
CODE CHART )

3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)

a. Disconnect the A24 ECM connector.

b. Turn the ignition switch to ON.

c. Check that the MIL is not illuminated.

OK: MIL is not illuminated.

Fig. 316: Identifying A24 ECM Connector

NG : Go to step 4

2008 Toyota Tundra

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

OK : REPLACE ECM (See REMOVAL )

4. CHECK HARNESS AND CONNECTOR (COMBINATION METER - ECM)

a. Disconnect the A24 ECM connector.

b. Disconnect the J28 combination meter connector.

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

Standard resistance

STANDARD RESISTANCE SPECIFICATION

Fig. 317: Identifying A24 ECM & J28 Combination Meter Connectors

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : REPAIR OR REPLACE COMBINATION METER ASSEMBLY (See COMBINATION
METER ).

5. CHECK THAT MIL IS ILLUMINATED

a. Check if the MIL is illuminated when the ignition switch is turned to ON.

OK: MIL should be illuminated.

Tester Connection

Condition Specified Condition

A24-24 (W) or J28-5 (CHK) - Body ground Always

10 kohms or higher

2008 Toyota Tundra

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