Change is inevitable. But that doesn’t mean it has to be difficult. Take for instance electronic devices in performance cars. Sophisticated hardware was once rare in hot rods, street machines, and race cars, but now the opposite is true – all but the most hardcore retro builds today generally carry their share of electronic systems.

And those devices are easier than ever to use, typically working together with plug-and-play simplicity that makes it practically a no-brainer to get the benefits of modern engineering in any car. The secret is a technology called CAN Bus, an abbreviation for Controller Area Network. It’s an industry-standard communications protocol designed into many components offered by AEM, Racepak, MSD, and other Holley brands. It makes performance electronic equipment simpler to install, more adaptable, and vastly more capable.

Developed by Bosch and officially released as a communications protocol at a Society of Automotive Engineers (SAE) conference in Detroit, Michigan in 1986, the introduction of the CAN bus system was nothing short of a revolution in automotive technology integration. Prior to CAN bus, vehicles used point-to-point wiring for communications between electronics, and as automotive designs became more reliant on computer-controlled devices in the late ‘70s and early ‘80s, the approach had become expensive, convoluted, and increasingly unreliable.

By creating a standardized communications protocol, CAN bus took a more sophisticated approach that allowed various electronic devices throughout the vehicle to communicate with each other and, in some cases, make adjustments based on the data shared between those devices. CAN bus saw its first use in mass-produced vehicles with the introduction of the W140-generation Mercedes-Benz S-Class in 1991. In the years since, the communications standard has proliferated throughout the automotive industry. As Donny Cummins of Racepak Data Systems explains, it’s not hard to see why the standard became so popular.

“Prior to CAN bus, you were essentially hardwiring everything. So if you had 15 devices going in a vehicle, that’s at least thirty wires for just power and ground. So the wiring got complex very quickly. But with CAN bus you could suddenly run a small amount of wiring throughout the vehicle with multiple devices attached to it in a network layout, which allowed everything to talk to one another. One device could receive data from another device at the other end of the car and react accordingly.”

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Although CAN bus originated among mainstream automakers, the performance aftermarket soon saw its advantages too. The result is increased capability of all types of aftermarket electronics, along with easier installation and wider compatibility.



A Robust Communications Platform

The ability for CAN bus devices to self-check and report faults also provided immediate benefits for vehicle diagnostics and troubleshooting, but OEMs also saw how the protocol’s modularity and interoperability presented an opportunity to develop “active” technologies that could react in real-time to data provided by other systems in the vehicle.

“Suddenly you could have everything from the engine and gearbox to the antilock brakes and wheel-speed sensors talking to one another,” Cummins says. “And that raised the level of precision and sophistication of everything from transmission shift scheduling to traction and stability control.” The aftermarket soon identified the advantages that CAN bus offered as well. “Now you have this network that you can tap into. Early on it was mostly about using OBD-II readers to scan the system for error codes, but that access also allowed for reprogramming with handheld tuners that was much more advanced.”

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Importantly, the establishment of a standardized communications protocol meant that devices from various manufacturers could share data and work together in custom applications with minimal hassle. “Let’s say I’ve got a ’73 Chevy C10, and I decided I want to put in a set of reproduction gauges,” Cummins says. “I’ve also previously swapped out the original engine for an LS3 V8, and I’ve got a Holley EFI system controlling everything. In the past, a lot of the OE gauges would not easily hook up to a combination like this. But today we have OE-style gauges available that are CAN bus-capable. You’ve got one cable and an interface module that grabs all the data from the ECU and sends it to that gauge. It’s plug-and-play, adjustable, and very accurate.”

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High-Performance Automation

While its robustness, simplicity, and more advanced communications methods offer passive benefits, the ability for a CAN bus system to actively deliver commands based on the data received from devices on the network is perhaps its most powerful feature.

“Now you can create a logic – you can have multiple devices on the vehicle talking to one another and making adjustments based on the data that they’re sharing,” Cummins notes. “Let’s say you have a sensor on the engine that’s reading coolant temperature – in a CAN bus system, you can tell a device to kick on the fan when that coolant temperature reaches 190 degrees, and to keep that fan on until the reading drops below 160 degrees. You could also tell the system to change when those things happen based on whether or not the air conditioning is on, or other factors. That’s something that was much more difficult to do prior to CAN bus, and it was generally more of a switched ‘dumb’ system that couldn’t really be programmed easily.”

In recent years, the capability of CAN bus has been leveraged to incredible effect in performance applications. “The MSD Power Grid system is a great example of that,” says Cummins. “This system has an add-on accessory called the ARC (Advanced RPM Control) module, and the ARC module communicates with the ignition controller. If the ARC controller detects that the vehicle is losing traction because the speed sensors on the rear wheels or the driveshaft are showing numbers that don’t jibe with the G-meter – that is, the wheels are spinning, but the car isn’t actually moving forward at the proper rate – it can tell that ignition controller to retard the timing or make other changes to bring that back in line in a highly precise way. So you have, in effect, a fully customizable traction control system. It’s comparing baseline data that was set up in the software by the end user to the data that these sensors are seeing in real time, and it’s automatically making adjustments to correct that wheelspin.”

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This “active” characteristic of CAN bus can also greatly improve safety in high-performance applications. For instance, a fail-safe could be put in place that automatically shuts down the engine if a wheel sensor detects that the vehicle has traveled more than 1300 feet down the drag strip during a pass, or the system could be programmed to automatically deploy a parachute under similar circumstances.

“You could have a situation where you’re going down the track and the oil pressure suddenly drops,” Cummins says. “If you have the car set up to monitor oil pressure through the CAN bus system, you could tell the system to trigger a warning light if the pressure drops below a certain threshold, or just automatically shut down the engine. It’s the kind of situation where a controller can really pay for itself by preventing potentially catastrophic damage.”

In the years since the first CAN bus standard was introduced, newer iterations of it have allowed for faster data transmission speeds, more devices on a network, and greater resistance to electrical interference. These advancements have in turn provided companies like Holley, Racepak, and MSD with the headroom needed to continue to innovate.

“CAN bus has become incredibly versatile, and it’s only getting better,” says Cummins. “And as it evolves to handle more data and more devices, it allows us to improve our products alongside those advancements.”

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