PassThru is a function for programming control units according to the Euro 5 regulation. Since 1 March 2010, all OEMs are obliged to make technical repair information available to independent workshops and to enable the reprogramming of control units. For programming, a direct connection is established between the vehicle in the workshop and the manufacturer using PassThru, allowing new control unit software to be installed.

The Euro 5 Regulation also regulates the transmission of information from OEMs to workshops in addition to the permitted exhaust emission value levels. Therefore, since the introduction of the standard, service manuals, technical instructions, wiring diagrams, fault codes, information for the clear identification of the vehicles as well as information on special tools have to be released.

SAE-J2534 designates the international standard for the communication basis for programming control units in the vehicle. Each of the PassThru interfaces provided by Hella Gutmann has been designed and manufactured to meet the J2534 standard.

The OEMs prescribe different requirements for using their portals and, as a result, for programming the control units. These can be found on the relevant manufacturer's website.

42SE, mega macs 56, mega macs 66 or mega macs 77 with software version 49 SP 1 and a workshop PC with Internet access are required. In addition, the vehicle must be externally supplied with float voltage by a charger.

Workshop PC:

For this, the software version of the diagnostic device and the software version of the HGS PassThru set-up must match. These are made available for download on the Hella-Gutmann Solutions homepage.

mega macs PC, mega macs 42SE, macs macs 56:

The VCI must be connected directly to the workshop PC via USB (not via a hub) and plugged into the OBD interface of the vehicle. The workshop PC should be connected to the internet with a LAN cable (a stable WLAN internet is also possible) and if it is a notebook, it should be connected to a power source. Automatic standby or even switching off the PC must be deactivated

mega macs 66:

The DT66 module must be inserted in the module slot of the mega macs 66 and plugged into the OBD interface of the vehicle using the cable. The mega macs 66 must be connected directly to the workshop PC via USB (not via a hub). The workshop PC should be connected to the internet with a LAN cable (a stable WLAN internet is also possible) and if it is a notebook, it should be connected to a power source. Automatic standby or even switching off the PC must be deactivated.

Connect the device as described in item "Error! Unable to find reference source". Switch on the vehicle ignition and start the HGS PassThru communication test programme. Now click the "Start test" button. Now the connection between PC – VCI (mega macs 66) – Vehicle is tested and displayed with green or red arrows. For a more detailed description of the HGS PassThru communication test and troubleshooting, please refer to the manual.

Programming is started via the relevant manufacturer portal. An account must be created there. The costs for this function vary depending on the manufacturer. A good and up-to-date overview of manufacturers' websites can be found under the ZDK brochure "Informationen über den Zugang zu technischen Daten bei den Fahrzeugherstellern" (Information on access to technical data at vehicle manufacturers).

1. PC must not be switched off/put into standby
2. PC may not be used for any other purpose
3. Firewall must be deactivated or set (proxy)
4. The LAN connection must not be interrupted
5. The diagnostic device cannot be used for other work on the vehicle during this time
6. Vehicle must be supplied with external power
7. Additional consumers in the vehicle should be deactivated (observe OEM specifications)
8. The USB connection must not be interrupted

Unless otherwise specified by the OEM, the ignition must be switched off for at least 30 seconds after programming the control unit. After switching on the ignition again, a complete system test should first be carried out and the error memory read out and deleted. Errors typical of the system can occur during programming.

The initial commissioning of the vehicle must be specifically monitored and, if necessary, a test drive must be carried out. In any case, the manufacturer-specific instructions must be followed in order to avoid a defect in the programmed control unit.

Nothing! Provided that a mega macs PC, mega macs 42 SE, mega macs 56 or mega macs 66 is available and on software version 49 (SP1).

Vehicle manufacturers charge different costs for using their portals. There is also a separate portal for each vehicle manufacturer. A good and up-to-date overview can be found under the ZDK brochure "Informationen über den Zugang zu technischen Daten bei den Fahrzeugherstellern" (Information on access to technical data at vehicle manufacturers).

High-speed internet access is not mandatory, but it is highly recommended. The time it takes software to download from the OEM server is highly dependent on the download rate, so the time can be greatly reduced by using a faster internet connection.

The programming depends on which vehicle bus is used for communication. CAN bus is significantly faster than the K line. In addition, the time depends on the performance of the workshop PC used and the amount of data to be overwritten. The size can vary from a few kilobytes to several megabytes.

In principle, there are three different scenarios:
1. If repeat programming is supported and an error occurs during programming, the software in the control unit is overwritten again. This brings the control unit up to date despite the error. Programming simply takes longer than without errors.
2. If repeat programming is not supported and an error occurs, programming is aborted. If the programming can be undone, the control unit will not be updated. However, the function of the control unit remains the same.
3. If repeat programming is not supported and an error occurs, the process is aborted and the programming takes longer. If the programming cannot be resumed, the function of the control unit will be disturbed. This does not ensure safe functioning of the control unit, which means that it must be replaced.

Complications may arise if several different OEM portals are used simultaneously on one computer. However, in our experience, some vehicle manufacturers can also be combined, yet this combination can also have a negative impact depending on its use, and the use of other programmes. We therefore recommend ideally using only one vehicle manufacturer portal per PC/laptop. Partitioning the computer's hard disk with separate operating systems would also be an option. In any case, the vehicle manufacturer's system requirements must be observed.