Inspection Procedure

WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

Check communication circuit inside ECU.

PREPARATION:

Disconnect the following ECU connectors in order from the top downward.

HINT:

Before disconnecting the next connector, be sure that disconnected ECU connector is reconnected.

DTC DETECTION ITEM

Disconnect ECU connector	Connector No.
ECM	E2
A/C ECU	A11
Center cluster integration panel	C6
Combination meter	C12
Skid control ECU	S12
Airbag sensor assembly	A24
Passenger side J/B ECU	P4, PH

Fig 1: Checking Continuity Of Wire Harness Between Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CHECK:

Check the DTC every time each connector is disconnected.

OK:

DTC B1266 or B1267 is not output.

OK : Replace the corresponding ECU (ECU for which DTC is deleted is defective.) (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
NG : Go to next step.

2. Check for short circuit between ECUs.

PREPARATION:

Disconnect the following pairs of ECU connectors simultaneously, from the top downward.

HINT:

Before disconnecting the next connector, be sure that disconnected ECU connectors are reconnected.
The short circuit check can be preformed on the circuit by disconnecting it from the MPX communication bus circuit.

If DTC is deleted, this means that the circuit being checked is short-circuited and it must be repaired.

DTC DETECTION ITEM

Disconnect ECU connector	Connector No.
ECM A/C ECU	E2 A11
ECM Passenger side J/B ECU	E2 P4
Passenger side J/B ECU Airbag sensor assembly	P4 PH
Airbag sensor assembly Skid control ECU	A24 S12
Skid control ECU Combination meter	S12 C12

Fig 2: Checking Continuity Of Wire Harness Between Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CHECK:

Check the DTC every time a pair of connectors are disconnected.

OK:

DTC is B1266 or B1267 is not output.

OK : Repair or replace corresponding wire harness.
NG : Go to next step.

3. Check for short circuit.

PREPARATION:

Disconnect the following connectors of ECU.

HINT:

Before disconnecting the next connector, be sure reconnect the ECU connector that is already disconnected.

DTC DETECTION ITEM

Disconnect ECU connector	Connector No.
Gateway ECU Combination meter	G3 C12
Gateway ECU A/C ECU (w/o LEXUS navigation system) Center cluster Integration panel (w/ LEXUS navigation system)	G3 A11 C6

CHECK:

Check whether or not there is +B short and GND short between the above connectors.

Fig 3: Checking +B Short And GND Short Between Connectors

OK:

No +B short and GND short.

NG : Repair or replace corresponding ware harness.
OK : Repair the gateway ECU.