B2797

ENGINE IMMOBILISER: ENGINE IMMOBILISER SYSTEM (w/o Smart Key System): B2797: Communication Malfunction No. 1
B2797 - Communication Malfunction No. 1

DESCRIPTION

This DTC is output when a communication error occurs between the transponder key amplifier and transponder key ECU. Some possible reasons for the communication error are: 1) 2 or more ignition keys are positioned too close together, or 2) noise is occurring in the communication line.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK KEY





(a) Check if the ignition key being used is near other ignition keys. Also, check if the key ring is in contact with the key grip.

Result:





B -- CHECK TRANSPONDER KEY ECU (NOISE)
A -- Continue to next step.

2. CHECK FOR DTC

(a) Separate the keys from each other and / or remove the key ring.

(b) Clear the DTC Engine Immobiliser System (w/o Smart Key System).

(c) Insert a key into the ignition key cylinder. Remove it. Repeat for all other keys.

(d) Check that no DTC is output.

OK:

No DTC is output.

NG -- CHECK TRANSPONDER KEY ECU (NOISE)

OK -- END

3. CHECK TRANSPONDER KEY ECU (NOISE)





(a) Using an oscilloscope, check for noise in the waveform between the terminals of the E5 amplifier connector and E46 ECU connector.

OK:

No noise is present (see illustration).





NG -- FIND CAUSE OF NOISE AND REMOVE IT
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - TRANSPONDER KEY AMPLIFIER)





(a) Disconnect the E46 ECU connector.

(b) Disconnect the E5 amplifier connector.

(c) Measure the resistance of the wire harness side connectors.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK TRANSPONDER KEY AMPLIFIER (OPERATION)

(a) Temporarily replacing the transponder key amplifier with a new or normally functioning one Removal.

(b) Check that the engine starts normally.

OK:

Engine starts.

NG -- REPLACE TRANSPONDER KEY ECU Removal

OK -- END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)