This paper is focused on presenting the simulated solution for synchronizing the CAN communication, which is signal based, with the Pulse Width Modulation (PWM) for each LED connected to a LED matrix manager device. Using the presented solution, the user is able to read and verify each LEDand represents a very easy and fast testing approach for automotive lighting with LMM (LED Matrix Manager) devices. The information provided by the sniffer improves the error root cause detection time, offers an overview on the requirements compliance, and assures an efficient monitorisation of the LMM behaviour. The LMM sniffer is developed due to the missing of a dedicated standard solution for this purpose.