B1294 Transponder key ECU Communication stops

DESCRIPTION

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

DTC No.	DTC Detection Condition	Trouble Area
B1294	Transponder key ECU Communication stops	Transponder key ECU Wire harness

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

When "+B of 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.

1. CHECK OPERATION

1. 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	Go to step 4

NG

2. INSPECT FUSE (MPX-B)

1. Remove the MPX-B fuse from the instrument panel junction block.

2. Measure the resistance of the fuse.

   Standard resistance:

   Below 1 Ω
   

NG	REPLACE FUSE

OK

3. CHECK WIRE HARNESS (TRANSPONDER KEY ECU - BATTERY AND BODY GROUND)

1. Disconnect the T8 ECU connector.

2. Measure the voltage of the wire harness side connector.

   Standard voltage:

   Tester Connection	Specified Condition
   T8-1 (CPUB) - Body ground	10 to 14 V

3. Measure the resistance of the wire harness side connector.

   Standard resistance:

   Tester Connection	Specified Condition
   T8-14 (GND) - Body ground	Below 1 Ω

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4. CHECK RESISTANCE OF COMMUNICATION LINE

1. Disconnect the B7 and G1 ECU connectors.
   

2. Measure the resistance of the wire harness side connectors.

Standard resistance:

Tester Connection	Specified Condition
T8-4 (MPX1) - B7-21 (MPX1)	Below 1 Ω
T8-5 (MPX2) - G1-3 (MPD1)	Below 1 Ω

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
REPLACE TRANSPONDER KEY ECU