DTC B1262: A/C ECU communication stop: Wiring Diagram

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.

See DTC B1266 INSTRUMENT PANEL SYSTEM COMMUNICATION [| BUS MALFUNCTION (+B SHORT), DTC B1267 INSTRUMENT PANEL SYSTEM COMMUNICATION BUS MALFUNCTION (GND SHORT) .

Check wire harness.

PREPARATION:

Pull out the ECU connectors mentioned below.

DTC DETECTION ITEM

Wire harness side connector of ECU	Terminal
A/C ECU - ECM	MPX+ (A11-2) - MPX2 (E2-20)
A/C ECU - Integration control panel (w/o LEXUS navigation system)	MPX- (A11 - 4) - MPX+ (C6-3)
A/C ECU - Gateway ECU (w/ LEXUS navigation system)	MPX- (A11 - 4) - MPI1 (G3-5)

CHECK:

Check continuity of the wire harness between the connectors.

Fig 1: Checking Continuity Of Wire Harness Between Connectors

OK:

There is a continuity between the connectors.

HINT:

If there is OPEN in any wire harness, please repair it.

NG : Repair or replace wire harness.
OK : Replace A/C ECU (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).