Test Procedures
Basic Checks:
It is essential to make a number of basic checks before starting fault-tracing:
- Check that fuses 5 and 31 are OK.
- Once you have checked the fuses, it is easier to make the other checks with the test unit connected. For more information on the checks below [1][2]Description of On-Board Diagnostics
- Control module A:1 must be at 12 volts (# 1).
- Control module A:8 must be at 5 volts (# 8).
- Control module A:6 (# 6), A:9 (# 9), A:10 (# 10) and C:10 (# 56) must be at 0 volts.
Checking DTCs After Taking Action:
If fault-tracing leads to taking action to deal with the suspected fault, run a final check using the diagnostic system. Control module must be connected.
- Delete DTCs.
- Test run the ECC system:
- Start engine.
- Turn both temperature switches to min and max sellings. Leave for at least 15 seconds in each setting.
- Turn both air distribution switches to all symbol settings. Leave for at least 15 seconds in each setting.
- Set fan selector switch to "aut", 0, min. and max.
- Test with air-conditioning (A/C) switch in both ON and OFF settings.
- Test with REC switch in both ON and OFF settings.
Read off DTCs:
Run test mode 1. See "On Board Diagnostic Test Modes." If 1-1-1 appears, no fault found by diagnostic system. If other DTCs appear, use fault-tracing procedure for each DTC. [1][2]Description of On-Board Diagnostics
NOTE: If all faults have been dealt with, only diagnostic trouble code (DTC) 1-1-1 will appear.
Test Points And Symbols:
The control module has contacts for three connectors. The connecting pins are designated A:1 to A:30, B:1 to B:16 and C:1 to C:10 for the three connectors. The Image shows connector B.
For connectors on components, the connecting pins are numbered 1, 2, 3 etc. or 1A, 2A, 1B etc. Always take readings from such connectors from a diagram showing the pin numbers. Designations appear on the wiring diagram.
Test unit connections to test equipment are numbered #1, #2, #3 etc. Symbols are used when describing fault-tracing procedures. For the most common symbols explanation Electronic Climate Control
A simplified circuit diagram is used in fault tracing for DTCs. The cables and test points fault-tracing shows are marked with heavier lines or circles. For the branching points included in simplified circuit diagrams (e.g. branching point 23/3O6 in Image) and also described in the fault-tracing procedure, in other Image there is an overview showing where they are located.
Test Equipment:
"Test Unit," commonly referred to throughout these diagnostic procedures is Volvo's term for their breakout box.
Voltmeters and ohmmeters (or a multimeter which can be used for volt or ohm readings) are used in these fault-tracing procedures.
Voltage readings. Voltage readings on connector contacts can be made on the side of the connector, but are easier to make via the test unit connected. When taking voltage readings, connect the voltmeter - terminal to ground GND (0 V) and the + terminal test probe to the test point indicated. When making a number of voltage readings in succession, it will be enough to move the + terminal test probe between different test points (keeping the GND connection).
Resistance readings. Resistance readings across a component can be made by connecting the test unit (without the control module), although taking resistance readings on cables usually involves disconnecting the cable connection from the component. See "On Board Diagnostic Test Modes." [1][2]Description of On-Board Diagnostics
Fault in cable or component. In the fault-tracing section on DTCs, we often refer to "Checking Cables" if there is reason to suspect an open circuit or GND fault in a cable.
Faults can of course also occur in components, e.g. as open circuits, GND faults or failure to operate.
The ECC control module can detect faults in the system, store DTCs which cover the types of faults described above and run a self-diagnosis on the control module and its programs (software).
Intermittent faults. With intermittent faults, the fault may be in the cables or connections. Check in accordance with the instructions below.
- If you suspect there is an intermittent fault, delete the DTCs once you have read them off. Test run the ECC system as shown in "Checking DTCs" and read off the DTCs again.
- If the DTC has disappeared, this may be due to an intermittent fault which has now returned to normal. Continue with "Checking cables" for the component the DTC indicates, and fault-tracing for the DTC.