Aftermarket March 2023

I was recently asked by a trade customer of mine if we could “simply” program a new headlight module for a VW Golf MK7. They had replaced a control unit due to the dipped beam headlamp not operating. They advised me that after the unit was installed the light started working. with the other lights all operating correctly. However, there was a bulb warning in the dash display Please refer to Fig. 1. At this point the request would seem normal and a 30 AFTERMARKET MARCH 2023 TECHNICAL www.aftermarketonline.net SHINING A LIGHT ON THE ROOT CAUSE FAILURE A headlight fault on a VW Golf shows that getting to the actual problem can be made more difficult if you do not follow the right process straightforward job so we continued with the task in hand. Correctly programming new headlamp control modules on VAG vehicles will require the dealer tool for this manufacturer, known as ODIS (Offboard Diagnostic Information System). I connected this tool to the vehicle and carried out a full system scan. This is a common practice when attempting to program any control modules as programming errors can occur after the process is done and having a report before and after the programming is very beneficial. It can also aid in any warranty claims. As you can see the only fault codes being set are “Headlamps No Basic Setting” and another fault code relating to “Right Headlamp Power Output Stage.” Please refer to Fig. 2. These codes were both permanent and would not clear. I expected to see the basic settings code, as the control module had not yet been programmed. However, the other code seemed odd to me initially. Why programming is rarely straightforward I pressed on and attempted to carry out the basic settings of the right-hand headlamp dipped beam control module, which our customer had replaced, but I kept receiving a communication error, as seen in Fig. 3. This seemed very odd as there were no communication fault codes present and all the front lights were operational. After a few failed attempts I believed there could possibly be another issue with this headlamp which was not analysed initially by the original garage. Using the dealer tool, I accessed the information section and reviewed the wiring diagram for the headlight. BY Ryan Colley, Elite Automotive Diagnostics Fig 1