CAN-Bus Comfort System, Checking
CAN-Bus Comfort System, Checking
NOTE:
- If the connector is removed from one control module connected to the CAN-bus system and the ignition is switched on, a malfunction entry can occur in another control module connected to the CAN-Bus. The same applies, if (e.g. by pulling a fuse) the voltage supply is interrupted.
- The Control module with indicator unit in instrument cluster -J285- is the interface between the two bus-systems. In addition -J285- is the decisive (determining) control module in the CAN-bus comfort system, via the adaptation function control modules that are connected to the CAN-bus comfort system are entered into this control module (-J285-) (depending on equipment level).
- You can determine how many control modules are connected to the CAN-bus system, based on the wiring diagram.
Isolating possible malfunction causes
NOTE: The following malfunction locations and malfunction types apply to the CAN-bus comfort system:
- VW-group CAN-bus comfort system
- Faulty:
No data can be transferred via the Bus-system
- in single wire mode:
No data can be transferred on of the one Buslines (CAN-Hi or CAN-Lo)
- Missing messages (time out for various control modules):
No data was received by one or more control modules within a specified time period.
- Control module with indicator unit in instrument cluster
- Vehicle Electrical System Control Module -J519
- Steering Column Electronic Systems Control Module -J527-
- Central control module for comfort system -J393-
- No communication
No data is received from Control module with indicator unit in instrument cluster -J285-, Central control module for comfort system -J393, Vehicle Electrical System Control Module -J519 and/or Steering Column Electronic Systems Control Module -J527-
- Check DTC memory:
Control module with indicator unit in instrument cluster -J285-, -J393-, -J519- or -J527- cannot send information due to a malfunction on a in serial connected component.
- Convertible Top Control Module -J256-
- No communication:
No data is received from Convertible Top Control Module -J256- (Before continuing with further troubleshooting, check the coding of A/C control module -E87- and the installation of this optional equipment).
- Check DTC memory:
Convertible Top Control Module -J256- cannot send information due to malfunction on a in serial connected component.
- CAN-bus system
- Check DTC memory:
Control module with indicator unit in instrument cluster -J285- cannot send information, due to a malfunction on a control module connected to the CAN-bus system (Check DTC memory of instrument cluster control module).
Determining malfunction in CAN-bus comfort system
- With ignition switched off connect VAS 5051 Vehicle Diagnostic, Testing and Information System with VAS 5051/1 diagnostic cable to 16-pin data link connector on vehicle. Connecting VAS 5051 Tester
- Switch ignition on.
- Press button -0- twice for function "Automatic test procedure".
Indicated on display of VAS 5051:
All address words stored in VAS 5051 are sent to the vehicle one after another via the diagnostic cable.
Indicated on display of VAS 5051:
- Display field 1 shows which address word is currently transferred to VAS 5051.
- Display field -2- shows which control modules answered. In addition the amount and type of malfunction stored in that control module is displayed.
- Wait until "Function ended" is shown in display field -1-.
NOTE:
- Before checking the CAN-bus wiring system, check whether a malfunction is stored in a control module which cannot exchange data with other control modules and eliminate malfunction as necessary.
- The data exchange with other control modules can be interrupted, if a control module stores a malfunction, although this malfunction may not apply to the CAN-bus-system.
- Check part number with index of control module that does not communicate.
Malfunction(s) on the CAN-bus comfort system are only indicated by the A/C Control Head -E87-:
- Check coding of A/C Control Head -E87-. Code Control Module (Function 07)
- Check data lines (wires) to A/C Control Head -E87- for open circuit or wiring resistance.
Wire resistance: max: 1.5 Ohms
NOTE: Watch for possible loose contact in the wiring and connectors.
If no malfunction can be determined, malfunction is in A/C Control Head -E87-.
Malfunctions on the CAN-bus comfort system are indicated in another control module:
- Check data wires and respective shielding between the different control modules connected to the CAN-bus comfort system for open circuit and wiring resistance.
Wire resistance: max: 1.5 Ohm
- Check data wires and respective shielding between the different control modules connected to the CAN-bus comfort system for short circuit against each other, short to B+ and Ground (GND).
NOTE:
- Watch for possible loose contact in the wiring and connectors.
- If this malfunction is not displayed on all connected control modules, it is possible that there is an open circuit at one connecting point in wiring.
If no malfunction is determined and all other control modules connected to the CAN-bus comfort system show this malfunction, there is a malfunction in one of the connected control modules.
- Check version, coding and the entered adaptation of Control module with indicator unit in instrument cluster -J285-.
- Check version and coding of other control modules connected to the CAN-bus comfort system (e.g. Vehicle Electrical System Control Module -J519-, Steering Column Electronic Systems Control Module -J527-).
- Disconnect all control modules from the CANbus system except the Control module with indicator unit in instrument cluster (interface to CAN-bus system) and the Steering Column Electronic Systems Control Module -J527-.
- Erase DTC memory of Control module with indicator unit in instrument cluster.
- Check DTC memory of instrument cluster and Steering Column Electronic Systems Control Module -J527-.
If the malfunction on the CAN-bus comfort system no longer appears, malfunction is in one of the connected control modules.
- Connect in sequence the different control modules again.
- Check DTC memory after connecting each control module.
- Replace control module if malfunction appears again after it has been connected again.
If the malfunction on the CAN-bus comfort system is still displayed, there is malfunction in the Control module with indicator unit in instrument cluster or in the Steering Column Electronic Systems Control Module -J527-.
- Disconnect Control module with indicator unit in instrument cluster and connect another (e.g. A/C control head -E87-).
- Check DTC memory of Instrument Cluster again.
NOTE: By disconnecting the instrument cluster and connecting another control module, a faulty module can be determined.
- Replace faulty control module