Diagnostic Trouble Codes (DTCs)
When a fault occurs it is stored in the control module as a DTC (Diagnostic Trouble Code) provided the car's road speed is over 35 km/h (22 mph) for at least 15 seconds.
The DTCs can be stored in the control module's memory only if the ignition is turned on. When the ignition is switched off these diagnostic trouble codes (DTCs) are erased. For the control module to detect DTCs again the car's road speed must be over 35 km/h (22 mph) for at least 15 seconds.
Reading Off Volvo On-Board Diagnostic (OBD) System
Information about faults and other information can be read off using the Volvo Scan Tool (ST) connected to the data link connector (DLC).
The Volvo Scan Tool (ST) communicates with the cruise control using a standard communications interface.
The data link connector (DLC) is located on the left of the center console under the dashboard.
The Volvo Scan Tool (ST) can be used to
- Read and erase the diagnostic trouble codes (DTCs).
- Check input signals to the control module.
- Read out the last reason that the cruise control was disengaged.
Activating Volvo on-board diagnostic (OBD) system
- Ignition ON
- normal battery voltage.
Reading and erasing diagnostic trouble codes (DTCs)
Used for reading out and erasing DTCs stored in the control module.
The OBD system can identify four types of fault and assign diagnostic trouble codes (DTC) to them.
For a list of diagnostic trouble codes (DTCs) and fault-tracing, see Response and Diagnostic Trouble Code (DTC) Tables .
Connect Volvo Scan Tool (ST).
HINT: The diagnostics on the cruise control system differ from many of the other diagnostic system functions in that the DTCs are only stored until the engine is turned off. So it is important not to turn off the ignition after a test drive until any DTCs that have been stored have been read off using the Scan Tool (ST).
HINT: Another difference is that the control module must receive a vehicle speed signal (VSS) above 35 km/h (22 mph) for at least 15 seconds before it will store any DTCs.
Note. If the engine is turned off after a test drive the DTC 1-1-2 will always be stored when the ignition is turned on. The test drive must then be carried out again.
Erase diagnostic trouble codes (DTC)
- by turning the engine off
- by using the Scan Tool after the DTCs have been read.
Response and Diagnostic Trouble Code (DTC) Tables
Note. Switch off ignition when connecting and disconnecting connector. Otherwise the control module could be damaged.
| Response Code | Response Text |
|---|---|
| 1-1-3 | Checking ON/OFF selector switch, brake and clutch valves |
| 1-2-3 | Checking RESUME switch |
| 1-3-1 | Checking SET+ switch |
| 2-1-3 | Checking SET- switch |
| 1-3-2 | Checking the brake light switch |
| 2-2-3 | Checking Park/Neutral Position switch (PNP) (automatic transmission) |
| 3-1-1 | Multiple simultaneous signals |
CONFIRMATION OF COMPONENT ACTIVATION (MODE 2)
| DTC | Fault message |
|---|---|
| 1-1-2 | Illegal vehicle speed signal |
| 1-2-2 | Vehicle speed has not exceeded 35 km/h (22 mph) or no vehicle speed signal |
| 2-1-1 | Internal fault in control module |
| 2-1-2 | Fault in vacuum pump or regulator circuit |
DIAGNOSTIC TROUBLE CODES (DTCs)
| Response code | Response text |
|---|---|
| 1-1-4 | Safety disengagement |
| 1-4-1 | Start inhibitor |
| 4-1-1 | Switch, brake or clutch |
| 1-2-4 | Brake light |
| 2-1-4 | Supply/not connected |
READ INPUT AND OUTPUT SIGNALS (MODE 5)
Scheme 70
This function provides confirmation that certain of the system components are operating. The test consists of activating one component after the other. The control module gives a confirmation in the form of a code if it positively identifies the component as activated. In this way both the component operational status and circuit integrity checks (open-circuits and short-circuits) can be carried out at the same time.
The following components are tested
- ON/OFF switch
- brake pedal valve
- clutch pedal valve
- RESUME switch
- SET+ switch
- SET- switch
- brake light switch
- Park/neutral position (PNP) switch (automatic transmission).
See Reading off Volvo on-board diagnostic (OBD) system
See Reading off Volvo on-board diagnostic (OBD) system