ECU Power Source Circuit: Procedure

WARNING: This page is about a different variant/trim than selected.

CHECK HARNESS AND CONNECTOR (TCM - BODY GROUND)

Turn the ignition switch off.

Fig 1: Identifying TCM Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the TCM connectors.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
B52-8 (E1) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

INSPECT ECU TERMINAL VOLTAGE (+B TERMINAL)

Disconnect the TCM connectors.

Fig 2: Identifying TCM Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Turn the ignition switch to ON.

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
B52-18 (+B) - Body ground	Ignition switch ON	11 to 14 V

NG → See step 3

OK → See step 4

CHECK HARNESS AND CONNECTOR (TCM - ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

Turn the ignition switch off.
Disconnect the TCM connector.
Remove the engine room junction block assembly from the engine room relay block.

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

Fig 3: Identifying TCM Connector & Engine Room Junction Block Assembly

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
B52-18 (+B) - 2E-7	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
B52-18 (+B) or 2E-7- Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK → See step 5

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to PROBLEM SYMPTOMS TABLE
GO TO ECM POWER SOURCE CIRCUIT (ENGINE CONTROL SYSTEM / SFI SYSTEM). Refer to ECM Power Source Circuit