Inspection Procedure

WARNING: This page is about a different car, the 2008 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL
1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
  CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

CHECK FOR OPEN IN CAN BUS WIRE (4WD CONTROL ECU BRANCH WIRE)

Disconnect the A28 4WD control ECU connector.

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

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

Tester Connection	Switch Condition	Specified Condition
A28-19 (CANH) - A28-20 (CANL)	Ignition switch off	54 to 69 Ω

NG: REPAIR OR REPLACE 4WD CONTROL ECU BRANCH WIRE OR CONNECTOR (CANH, CANL)

Fig 1: Identifying A28 4WD Control ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to Next Step

CHECK HARNESS AND CONNECTOR (4WD CONTROL ECU - BATTERY AND BODY GROUND)

Reconnect the cable to the negative (-) battery terminal.
Disconnect the A29 4WD control ECU connector.

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

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

Tester Connection	Condition	Specified Condition
A29-4 (GND) - Body ground	Always	Below 1 Ω

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

Standard Voltage

TESTER CONNECTION SPECIFIED CONDITION REFERENCE CHART

Tester Connection	Switch Condition	Specified Condition
A29-3 (IG) - Body ground	Ignition switch ON	11 to 14 V

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 2: Identifying A29 4WD Control ECU Connector Terminals

OK: REPLACE 4WD CONTROL ECU (See REMOVAL )