BS. Checking Communication With SRS Control Unit

BSA. Information On Trouble-Shooting







Condition


NOTE: Before beginning trouble-shooting, check that correct memory cassette is being used in Volvo System Tester.


Possible Source
Open circuit, short-circuit to ground or short-circuit to voltage supply in the wire to the data link connector
Open circuit in power supply, effective ground or signal ground to data link connector
Open circuit in power supply to SRS control unit
Defective Volvo System Tester, wiring or adapter.


NOTE: Check battery voltage before starting the fault search.


Fault Symptom(s)
No communication with SAS diagnostic system.


BSB. Checking Communication With SRS Control Unit







BSB1. Checking communication with ABS system

Ignition off.
Connect Volvo System Tester to data link connector.
ignition on.
Supply power to the Volvo System Tester.

Try to establish communication with ABS system.
Is there any communication with the ABS system?
Yes: Go to BSB2.
No: Go to BSB5.


BSB2. Checking wires





Ignition off.
Disconnect the Volvo System Tester from the data link connector.
Disconnect the battery negative lead.
Disconnect control unit.

Check the wire between the control unit pin 9 and data link connector pin 7 for an open circuit as described in BWA2, or short-circuit to ground as described in BWA3. See General Tests

Connect an ohmmeter between the battery positive terminal and the data link connector pin 7. Test for a short circuit to voltage supply BWA4.

Check the connector for contact resistance and oxidation, as described in BWA5. Do the necessary corrective action.



Additional Information






The voltage at the control unit connector pin 9 should be approximately 10 V
To access/replace control unit,
Has the open circuit been found?
Yes: Go to BSB8.
No: Go to BSB3.


BSB3. Checking voltage supply to control unit






Ignition on.
Using a voltmeter, test between the control unit connector pin 5 and ground.
The voltmeter should display the battery voltage.

If reading is OK: Go to BSB4.
If reading is incorrect: Trouble-shoot as described in AWC. ROPS Trouble Codes, Signal too low. Permanent fault


BSB4. Replacing the component

Test by replacing the control unit.
Then continue with BSB8.


BSB5. Checking Volvo System Tester

Check Volvo System Tester power supply and ground to data link connector as described in Volvo System Tester manual.
Has the fault been found?
Yes: Go to BSB8.
No: Go to BSB6.


BSB6. Checking communication wires ABS system






If communication with ABS-system is not possible, there is a fault in the circuit between the connected control units in the circuit and the data link connector.
Check the data link connector for contact resistance and oxidation as described in BWA5. See General Tests


Check the data link connector pin 7 and the connected control units for a short-circuit to ground, as described in BWA3, a short-circuit to voltage supply, as described in BWA4 and for an open circuit, as described in BWA2.


HINT: For information about the circuit to data link connector, see the applicable wiring diagram.


If no fault is found, check the Volvo System Tester as per service manual Volvo System Tester. Do the necessary corrective action.


Additional Information:






To access/replace control unit,
Then continue with BSB7.



BSB7. Checking communication wires ABS system, continuation






Ignition on.
Check the data link connector pin #7 and ground for a short-circuit to voltage supply, as described in BWA4. See General Tests Do the necessary corrective action.

Additional Information:
Voltage in communication wires should be 9-11 V with ignition on. This applies when fault localization instrument is not connected
Access/replace control unit,
Then continue with BSB8.


BSB8. Verification






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


Ignition off.
Connect the connectors, install the components.
Ignition on.
Try to establish communication with the SRS system.
Has contact been established?
Yes: Fault corrected
No: Fault not found