Communication

When a key is inserted into the ignition key cylinder but no communication occurs between the key and transponder key ecu, dtc b2796 is output. When a key is inserted into the ignition key cylinder but a communication error occurs between the key and transponder key ecu, dtc b2798 is output.

1. 1
   Read value of intelligent tester (engine immobiliser system)
2. 2
   Connect the intelligent tester (with can vim) to the dlc3.
3. 3
   Turn the ignition switch on with a key that cannot start the engine.
4. 4
   On the intelligent tester, enter the following menus: diagnosis / obd/mobd / immobiliser / data list / immobiliser. Read the result.

   

1. 1
   Check whether engine starts with other key
2. 2
   Check whether the engine starts with the vehicle's other keys.

1. 1
   Read value of intelligent tester (transponder key coil)
2. 2
   Connect the intelligent tester (with can vim) to the dlc3.
3. 3
   Turn the ignition switch on with a key that cannot start the engine.
4. 4
   On the intelligent tester, enter the following menus: diagnosis / obd/mobd / immobiliser / data list / antenna coil. Read the result.

   

4. Check wire harness (transponder key ecu - transponder key amplifier)

1. 1
   Disconnect the e46 ecu connector.
2. 2
   Disconnect the e5 amplifier connector.
3. 3
   Measure the resistance of the wire harness side connectors.

Standard resistance

1. 1
   Check transponder key amplifier (operation)
2. 2
   Temporarily replace the transponder key amplifier with a new or normally functioning one..
3. 3
   Check that the engine starts normally