Control Module Communication
Condition:Volvo Scan Tool (ST):
- The fault is permanent.
- Correct memory cassette being used.
Possible Source:
If the combined instrument panel gauges are working:
- Poor battery voltage.
- Open-circuit, short-circuit to ground or short-circuit to supply voltage in cable to data link connector (DLC).
- Open-circuit in data link connector (DLC) supply voltage or ground.
- Defective Volvo Scan Tool (ST) Volvo Scan Tool (ST) wiring or transmission.
If the gauges do not work:
- Open-circuit in 15-supply.
- Open-circuit in 30-supply.
- Open-circuit in combined instrument panel signal ground.
NOTE: If the communications problem only occurs with the car stationary and the ignition on (in position II) or when starting the engine: Connect a battery charger or extra battery.
Start fault-tracing with "Checking Control Module Communication", below.
Checking Control Module Communication:
1) Checking Power Supply:
Ignition On:
- Ignition on.
Volvo Scan Tool (ST):
- Volvo Scan Tool (ST) connected to data link connector (DLC).
- Power up the Volvo Scan Tool (ST) and check that the display lights.
- Does the display light?
Yes: Go to step 3, below.
No: Go to step 2, below,
2) Checking Volvo Scan Tool (ST):
- Check the Volvo Scan Tool (ST), power supply and data link connector (DLC) ground.
- Then continue with step 23, below.
3) Checking Communication With ABS System:
Ignition On:
- Ignition on.
Volvo Scan Tool (ST):
- Volvo Scan Tool (ST) connected to data link connector (DLC).
- Try to establish communication with the ABS system.
- Has communication with the ABS system been established?
Yes: Go to step 4, below.
No: Go to step 15, below.
4) Checking the Combined Instrument Panel:
Engine Running:
- Start engine
- Check that the tachometer is working.
- Is the tachometer working?
Yes: Go to step 5, below.
No: Go to step 6, below.
5) Checking for an Open-Circuit:
- Check cable between data link connector (DLC) terminal 7 and combined instrument panel # B4 for an open-circuit. Checking Cables and Terminals
- Then continue with step 23, below.
6) Checking 15-Supply Before Fuse:
Ignition On:
- Ignition on.
- Remove fuse 11/2. (This number represents an eleven "slash" two, not one and a half.)
- Connect a voltmeter between the rear output (positive side) on the fuse holder to fuse 11/2 and ground.
- The voltmeter should read approx. battery voltage.
If reading is OK go to step 8, below.
If reading is incorrect go to step 7, below.
7) Checking for an Open-Circuit:
- Check cable between the rear Output (positive side) on the fuse holder to fuse 11/2 and the battery for an open-circuit. Checking Cables and Terminals Check function of overload relay 2/31 and ignition switch. For further information about the circuit, see Wiring Diagram.
- Then continue with step 23, below.
8) Connecting Breakout box and Checking Ground Terminal:
- Ignition off.
- Reinstall fuse 11/2.
Test Box On Cable Harness Dashboard:
- Connect breakout box and check ground terminal according "Connecting the Breakout Box". Connecting Test (Breakout) Box
- Was ground terminal OK?
Yes: Go to step 10, below.
No: Go to step 9, below.
9) Corrective Action:
- Remedy fault if not already carried out.
- Then continue with step 23, below.
10) Checking 15 Supply to Combined Instrument Panel:
- Ignition off.
- Connect combined instrument panel.
Ignition On:
- Ignition on
- Connect a voltmeter between # 15 (# A15) and # 18 (# A18) on the breakout box.
- The voltmeter should read approx. battery voltage.
If reading is OK, go to step 12, below.
If reading is incorrect, go to step 11, below.
11) Checking for an Open-Circuit:
- Check cable between the rear output (positive side) on the fuse holder to fuse 11/2 and combined instrument panel # A18 for an open-circuit. Checking Cables and Terminals
- Then continue with step 23, below.
12) Checking Fuse on Combined Instrument Panel Printed Circuit Board:
- Ignition off.
- Check fuse on combined instrument panel printed circuit board. Service and Repair (Individual Component Replacement.)
- Was the fuse defective?
Yes: Go to step 13, below.
No: Go to step 14, below.
13) Checking for a Short-Circuit and Replacing Component:
- Check circuit after fuse on the printed circuit board for a short-circuit to ground. Permanent Fault
- For information about the circuit after the fuse, see wiring diagram.
- Replace fuse and reinstall combined instrument panel. Service and Repair Both, Instrument Panel removal and Individual Component Replacement have relevant information.)
- Then continue with step 23, below.
14) Fault Cause and Checking for Contact Resistance and Oxidation:
- The cause of the fault has been loose connections in the combined instrument panel connectors. Check combined instrument panel connectors for contact resistance and oxidation and remedy. Permanent Fault
- Then continue with step 23, below.
15) Checking Communication Cable to Data Link Connector (DLC):
- Ignition off.
- Connect breakout box and check ground terminal. Connecting Test (Breakout) Box
- Connect an ohmmeter between data link connector (DLC) terminal 7 and # 34 (# B4) on the breakout box.
- The ohmmeter should read approx. 0 Ohms.
If reading is OK, go to step 17, below.
If reading is incorrect, go to step 16, below.
16) Checking for an Open-Circuit:
- Check cable between data link connector (DLC) terminal 7 and combined instrument panel # B4 for an open- circuit. Permanent Fault
- Then continue with step 23 below.
17) Checking the Communication Cable:
- Ignition off.
- Connect combined instrument panel.
Ignition On:
- Ignition on.
- Connect a voltmeter between data link connector (DLC) terminal 7 and ground.
- The voltmeter should read approx. 9 - 11 V.
If reading is OK, go to step 20, below.
If value is lower, go to step 18, below.
If value is higher, go to step 19, below.
18) Checking for a Short-Circuit to Ground:
- Check cables between data link connector (DLC) terminal 7 and control modules connected to this cable for a short-circuit to ground, Permanent Fault
- For further information about the circuit, see Wiring Diagram.
- Then continue with go to step 23, below.
19) Checking for a Short-Circuit to Supply Voltage:
- Check cables between data link connector (DLC) terminal 7 and control modules connected to this cable for a short-circuit to supply voltage. Permanent Fault
- For further information about the circuit, see Wiring Diagram.
- Then continue with step 23, below.
20) Checking Communication with the Combined Instrument Panel:
Ignition On:
- Ignition on.
- Volvo Scan Tool (ST) connected to data link connector (DLC).
Volvo Scan Tool (ST):
- Try to establish communication with the combined instrument panel.
- Has communication been established with the combined instrument panel?
Yes: Go to step 21, below.
No: Go to step 22, below.
21) Fault Cause and Checking for Contact Resistance and Oxidation:
- The cause of the fault has been loose connections in the data link connector (DLC) and/or combined instrument panel connectors.
- Check data link connector (DLC) and combined instrument panel connectors for contact resistance and oxidation and remedy. Permanent Fault
- Then continue with step 23, below.
22) Checking Volvo Scan Tool (ST):
Volvo Scan Tool (ST):
- Check Volvo Scan Tool (ST).
- Then continue with step 23, below.
23) Verification:
Note: After carrying out the repair check that the fault has been remedied.
- Ignition off.
Connect Connector:
- Reconnect connectors, reinstall components.
- Combined instrument panel connected.
Ignition On:
- Ignition on.
Volvo Scan Tool (ST):
- Volvo Scan Tool (ST) connected to data link connector (DLC).
- Try to establish communication with the combined instrument panel.
- Has communication been established with the combined instrument panel?
Yes: Fault is corrected
No: The fault should now have been diagnosed and corrected. Since this is not the case the fault-tracing has failed. Do you want to quit fault-tracing?
Yes: Fault is not corrected
No: Start over again at step 1, above.