B1294

MULTIPLEX COMMUNICATION SYSTEM: B1294: Immobilizer ECU Communication Stop

DTC B1294 - Immobilizer ECU Communication Stop

DESCRIPTION
- This DTC is detected when communication between the transponder key ECU (Immobilizer ECU) and multiplex network gateway ECU stops for more than 10 seconds.

WIRING DIAGRAM

INSPECTION PROCEDURE
HINT: When "+B or GND short malfunction of communication bus" DTCs (B1214 and B1215) are detected at the same time as "communication stop" DTC B1294, repair the "+B or GND short malfunction of communication bus" DTCs first.

PROCEDURE

1. CHECK OPERATION
(a) Check if the engine start function operates normally through the ignition switch turned on.
HINT: With this inspection, the transponder key ECU CPU can be diagnosed if it works normally or not.

OK:
Engine start function operates normally.
OK -- CHECK RESISTANCE OF COMMUNICATION LINE
NG -- Continue to next step.
2. INSPECT FUSE (MPX-B)
(a) Remove the MPX-B fuse from the instrument panel junction block.
(b) Measure the resistance of the fuse.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - BATTERY AND BODY GROUND)

(a) Disconnect the T9 ECU connector.
(b) Measure the voltage of the wire harness side connector.
Standard voltage:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK RESISTANCE OF COMMUNICATION LINE
(a) Disconnect the B5 and G3 ECU connectors.

(b) Measure the resistance of the wire harness side connectors.
Standard resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE TRANSPONDER KEY ECU