It’s a common question among motorsport enthusiasts and those using apps like Harry’s LapTimer: Does Harry’s LapTimer use OBDII to access crucial vehicle data, especially parameters beyond basic engine readings? Specifically, when considering advanced data like brake pressure and throttle position, understanding the limitations and capabilities of OBDII is essential.
The reality is somewhat complex. While OBDII (On-Board Diagnostics II) is indeed often used as a connection point, its functionality for performance data acquisition is not straightforward. Since around 2006, most vehicles adopted a generic OBDII CAN (Controller Area Network) protocol, an improvement over the older, slower K-line systems. However, this generic protocol is primarily designed for emissions-related diagnostics. It provides a limited set of basic channels, typically including RPM, Engine Coolant Temperature (ECT), Manifold Air Temperature (MAT), Manifold Absolute Pressure (MAP), and Throttle Position Sensor (TPS). Critically, brake pressure information is not part of this standardized generic OBDII data set.
Alt text: OBDII port diagram illustrating pin assignments, highlighting pins 6 and 14 commonly used for CAN communication in modern vehicles, crucial for accessing extended vehicle data beyond standard emissions diagnostics.
Recognizing the limitations of generic OBDII, many vehicle manufacturers began implementing proprietary CAN data transmission through pins 6 and 14 of the standard J1979 (OBDII) connector shortly after the introduction of OBDII CAN. This proprietary data often contains a wealth of information, far exceeding the basic parameters available through generic OBDII. Manufacturers like GM Performance, some Stellantis brands, Ferrari, and others have been known to provide extensive data sets via this route. However, accessing this data requires the correct messaging protocols, scaling factors, and offsets to interpret the raw channel information.
Companies specializing in data acquisition, such as AiM and Racelogic, have invested significant effort in reverse-engineering these proprietary protocols for certain vehicle makes and models. This allows their devices to tap into richer data streams via the OBDII port. Conversely, some manufacturers, like Porsche and BMW, have initially focused on making this detailed vehicle data accessible primarily through their own proprietary apps, creating a more controlled ecosystem.
Currently, the landscape is varied. Many modern vehicles incorporate gateways or filtering systems that act as intermediaries, controlling and often limiting the data flow from the vehicle’s internal CANbus to the OBDII port. Despite these challenges, resourceful individuals and companies continue to investigate and decipher the available messaging to expand the range of accessible channels beyond the typically restricted generic OBDII set.
In conclusion, while Harry’s LapTimer and similar data acquisition tools often utilize the OBDII port as a convenient physical connection, it’s crucial to understand that OBDII itself is just an attachment point. The actual data availability is dictated by the vehicle manufacturer’s implementation, specifically what data they choose to transmit through pins 6 and 14, and the effort invested in reverse-engineering or accessing these proprietary channels. Therefore, whether Harry’s LapTimer can access specific data points like brake pressure through OBDII heavily depends on the car model and the extent to which the app (or user configurations) can interpret proprietary CAN data beyond the basic OBDII standards.
