Check Communication to Control Module [III]
III. Check the communication to the control moduleIIIA. Fault-tracing information
Condition
- Control module connected correctly
- Correct memory cassette used
Possible source
- Poor battery voltage
- Break, short circuiting to ground or short circuiting to power in the Data Link Connector cable
- Break in the Data Link Connector voltage supply, power ground or signal ground
- Defective Volvo System Tester, Volvo System Tester cabling or gear
Note! If the communication problem only occurs when the engine is started, connect the battery charger or an extra battery
Fault-tracing begins with [IIIB]. Check communication with the control module.
IIIB. Check communication with the control module
[IIIB1]
Check the power measurement
- Ignition on.
- Volvo System Tester connected to the Data Link Connector.
Turn on the power to the Volvo System Tester and check that the display is lit.
Is the display lit ?
Yes: IIIB3
No: IIIB2
[IIIB2]
Check the Data Link Connector
Check the Volvo System Tester, power measurement, power ground and signal ground to the Data Link Connector as per the Volvo Service Tester service manual
Continue thereafter with verification
If reading is OK: IIIB20
[IIIB3]
Connect the test box and check the contact points
Connect to test box as per JJJA. Connect the test box Connect the Test Box [JJJ]
Then proceed to: IIIB4
[IIIB4]
Check the voltage feed (15-feed)
- Ignition off
- Connect the control module
- Ignition on.
Connect a voltmeter between #23 and #8 on the test box.
The voltmeter should indicate the approx. battery voltage
If reading is OK: IIIB8
If reading is incorrect: IIIB5
[IIIB5]
Check fuse 11/29
Check that fuse 11/29 is intact
Is fuse 11/29 intact?
Yes: IIIB6
No: IIIB7
[IIIB6]
Check for cable breaks
Check the cable between control module #23 and ignition switch connection 15I for breaks as per [IIIB2].
Then continue with: IIIB20
[IIIB7]
Check for cable breaks and replace component
Check the cable between control module #23 and fuse 11/29 for breaks as per [IIIB2].
Thereafter replace the fuse
Then continue with: IIIB20
[IIIB8]
Check the voltage feed (30-feed)
- Ignition off
Connect a voltmeter between #9 and #8 on the test box
The voltmeter should indicate approx. battery voltage
If reading is OK: IIIB12
If reading is incorrect: IIIB9
[IIIB9]
Checking fuse
Check that fuse 11/14 is intact. (For 850 diesel fuse 11A/4, applies)
Is the fuse intact?
Yes: IIIB10
No: IIIB11
[IIIB10]
Check for cable breaks
Check the cable between control module #9 and the battery for breaks as per [IIIB2].
Then continue with: IIIB20
[IIIB11]
Checking for short-circuit and replacing component
Check wire between control module #9 and fuse 11/14 for short circuit to ground according to [IIIB3]. (For 850 diesel, check the wire between control module #9 and fuse 11A14 and #25 and fuse 11A/4 for short circuit to ground according to [IIIB3].)
Then replace the fuse.
Then continue with: IIIB20
[IIIB12]
Check the communication cable to the Data Link Connector
- Ignition off
- Disconnect the control module
- Volvo System Tester disconnected from the Data Link Connector
Connect an ohmmeter between Data Link Connector connection 7 and #13 on the test box
The ohmmeter should indicate 0 ohms.
If reading is OK: IIIB14
If reading is incorrect: IIIB13
[IIIB13]
Check for cable breaks
Check the cable between Data Link Connector connection 7 and control module #13 for cable breaks as per [IIIB2].
Then continue with: IIIB20
[IIIB14]
Check the communication cable
- Ignition off
- Connect the control module
- Ignition on
Connect a voltmeter between Data Link Connector connection 7 and ground
The voltmeter should indicate approx. 9-11 V.
If reading is OK: IIIB17
If value is lower: IIIB15
If value is higher: IIIB16
[IIIB15]
Check for short circuiting
Check the cable between Data Link Connector connection 7 and the control module for short circuiting to ground as per [IIIB3].
Then continue with: IIIB20
[IIIB16]
Check for short circuiting
Check the cable between Data Link Connector connection 7 and the control module for short circuiting to power as per [IIIB4].
Then continue with: IIIB20
[IIIB17]
Check communication with the ABS System
- Ignition on
- Volvo System Tester cabling connected to the Data Link Connector
Try to establish communication with the ABS system
Does the communication with the ABS system function?
Yes: IIIB18
No: IIIB19
[IIIB18]
Fault cause and check for contact resistance and oxidation
The cause of the fault has been poor contact in the Data Link Connector or control module connectors
Check the connectors and take appropriate action for contact resistance and oxidation as per Checking wiring and connections. Permanent faults Checking Wiring and Connections
Then continue with: IIIB20
[IIIB19]
Check the Volvo System Tester
Check the Volvo System Tester as per the Volvo System Tester service manual
Then continue with: IIIB20
[IIIB20]
Verification
Hint: After repair it is necessary to check that the fault has been rectified
- Ignition off
- Reconnect the connectors, components etc.
- Ignition on
- Volvo System Tester connected to the Data Link Connector
Turn on the power to the Volvo System Tester and try to establish communication with the ABS system
Is communication established ?
Yes: Fault corrected
No: IIIB21
[IIIB21]
Fault-tracing information
The fault should now have been diagnosed and corrected. Since this is not the case the fault-tracing has failed.
Do you want to exit fault-tracing?
Yes: Fault not corrected
No: IIIB1