BY. Checking Unlocking of Central Locking

BYA. Checking Unlocking Of Central Locking

BYA1. Checking connector on the SRS control unit






Ignition off.
Disconnect the battery negative lead.
Uncover and disconnect the connector from the SRS control unit, as described in Replacement of the SRS control unit.


CAUTION! Avoid touching the connector pin on the control unit. There is a risk of static discharge which can damage the control unit.


Check the cable terminals in the connector housing and the pins on the SRS control unit connector.


NOTE! The cable terminals must not be damaged or bent.


Replace and disconnect the connector from the SRS control unit. Check that the connector locks into the control unit.


Select one of the options.

Alternative 1: The connector housing and pins are OK. Go to BYA4.
Alternative 2: The pins on the control unit connector are defective. Go to BYA2.
Alternative 3: The connector housing is defective. Go to BYA3.


BYA2. Replacing the component






Replace the SRS control unit, as described in Replacement of the SRS control unit. Then continue with BYA13.


BYA3. Replacing the component
Check the wires and repair or replace the SRS insulation mat.
Then continue with BYA13.



BYA4. Checking the wire voltage






Ignition on.
Connect the battery negative lead.
Connect a voltmeter between the SRS control unit connector 34 and ground.
The voltmeter should display about 10 V.
If reading is OK: Go to BYA5.
If reading is incorrect: Go to BYA6.


BYA5. Information on fault localization

This result shows that there are no faults in the system.
Operation done


BYA6. Checking the wire resistance






Ignition off.
Disconnect the central locking control unit from the connector, See Replacing main control module in Alarms/Power Locks C70.


CAUTION! Avoid touching the connector pin on the control unit. There is a risk of static discharge which can damage the control unit.


Connect an ohmmeter between the SRS control unit connector 34 and the central locking control unit A10 for an open circuit, as described in BWA2 here in General Tests.


Additional Information






Access/replace control unit.
The ohmmeter should display approximately 0 Ohms.
If reading Is OK: Go to BYA8.
If reading is incorrect: Go to BYA7.


BYA7. Replacing the component

If when checking, the ohmmeter displays an infinite value, there is an open circuit in the wire between the central locking connector A10 and the SRS control unit connector 34.
Check the wire and repair or replace the SRS insulation mat.
Then continue with BYA13.


BYA8. Examine the wire to the central locking control unit to see if it has short-circuited to ground






Ignition off.
Disconnect the battery negative lead.
Connect the SRS control unit connector.
The connector to the central locking control unit must be disconnected.

Connect an ohmmeter between the central locking connector A10 and ground.
The ohmmeter should display approximately 1.2 Ohms.
If reading Is OK: Go to BYA9.
If reading Is incorrect: Go to BYA10.


BYA9. Replacing the component






Replace the central locking control unit. Replacing main control module. Power Locks Then continue with BYA13.



BYA10. Checking the wire between the central locking control unit and the SRS control unit






Ignition off.
Disconnect control unit.


CAUTION! Avoid touching the connector pin on the control unit. There is a risk of static discharge which can damage the control unit.


Connect a ohmmeter between the SRS control unit connector 34 and ground.
The ohmmeter should display infinite resistance.
If reading Is OK: Go to BYA11.
If reading is Incorrect: Go to BYA12.



BYA11. Replacing the component





There is no short circuit to ground in the wire between the SRS control unit connector 34 and the central locking connector A10.
Replace the SRS control unit.
Then continue with BYA13.


BYA12. Replacing the component

If when checking, the ohmmeter displays approximately 0 (there is a short circuit to ground in the wire between the SRS control unit connector and the central locking control unit.
Check the wire and repair or replace the SRS insulation mat.
Then continue with BYA13.


BYA13. Verification






HINT: After the repair it is necessary to check if the fault has been rectified.


Ignition off.
Connect the connectors, install the components, etc.
Connect the battery negative lead.
Connect a voltmeter between the SRS control unit connector pin 34 and ground.
The voltmeter should display approximately 10 V.
If reading is OK: Fault corrected
If reading is incorrect: Recheck for fault/rectify