WEBINAR TAKEAWAYS: PROVIDING TRUCK & TRAILER INSIGHTS DIRECTLY FROM THE ECU

The electronic control unit (ECU) holds key data for understanding vehicle performance, yet many overlook its potential because it seems complex. As a result, telematics providers often depend on multiple devices to achieve complete fleet visibility. In reality, much of the needed data, such as engine temperature or the brake status of a connected trailer, already travels through the truck’s CAN lines.

To help businesses make use of this feature, Teltonika hosted a webinar explaining how to access both truck and trailer data with a single FMC650 device.

HOW CAN BUS DATA IMPROVES HEAVY FLEET EFFICIENCY?

According to the ACEA reports, registrations of heavy vehicles in the European Union fell from 1 million to 800,000 in the first half of 2025. Logistics operators are slowing down the growth of their fleets, and now more than ever, focusing on efficiency. They are looking for solutions that maximise the performance of existing resources.

“That is where advanced insights from CAN data come in,” said Kseniya Dolia, chief of the SCOPE operational marketing group. “With precise vehicle information, telematics can help extend vehicle life, simplify compliance, and reduce major operational costs. Most importantly, it enables businesses to make difficult decisions based on reliable data.”

WHAT INSIGHTS CAN YOU PROVIDE WITH FMC650?

In Teltonika’s wide portfolio, FMC650 stands out for heavy fleet operations. It combines tachograph integration for remote file downloads with two CAN line connections, giving visibility into both truck and trailer performance.

Truck insights

Integrators can generate eco-driving reports based on FMS CAN data to evaluate how efficiently the driver used the truck’s controls during a trip. “Most trucks are equipped with fuel-saving features such as coasting and cruise control, which can reduce fuel consumption by up to 10%,” said Marharyta Smolenska, operational marketing coordinator at Teltonika.

To quantify the impact of driving style, the device calculates the fuel used, distance travelled, and time spent in each driving state and provides a comprehensive driver behaviour report at end of every trip.

For maintenance, FMC650 reads diagnostic trouble codes (DTCs) remotely, providing real-time and historical fault data. “This allows fleets to detect issues up to two weeks earlier than the check-engine light, shifting from reactive to proactive maintenance,” noted Marharyta.

Trailer insights

The key advantage of CAN data reading is that integrators can access communication between the truck and the coupled trailer.

“Every trailer is equipped with an Electronic Braking System (EBS) modulator. It controls braking and facilitates communication with the truck. The tracker listens to communication between the truck and the EBS modulator while installed in the truck cabin. This enables monitoring of both units through a single installation,” explained Marharyta.

With FMC650 trailer reading functionality, fleets can:

• Identify the connected trailer VIN for proper coupling

• Read applied braking forces to optimise maintenance

• Monitor tyre pressure to reduce fuel consumption

• Check live trailer weight to improve load accuracy and identify theft

Q&A

At the end of each of our webinars, we host a live Q&A session. Below, you will find some of the participants’ questions along with answers from our technical expert, Donatas Andriulionis.

Does TrailerCAN work with all trailer models and manufacturers?

Yes. Installation is carried out in the truck cabin, and the wiring depends on the truck manufacturer. Regardless of the trailer’s origin or model, trucks and trailers are coupled using a standardised protocol to coordinate braking. In other words, trailer information is transmitted through the truck’s CAN lines. For TrailerCAN to function, the trailer must be equipped with an EBS modulator. Most trailers have been fitted with EBS at the factory since around 2005–2008, while older trailers are usually retrofitted with it.

Is a connection to two CAN lines enough to implement all three functionalities?

Yes, two CAN lines are sufficient. The CAN1 line is used for an alternative FMS connection, providing access to both FMS data and diagnostic messages (DM1/DM2). The CAN2 line is dedicated to collecting trailer data.

What level of accuracy is the axle weight possible from the trailer?

This information comes through CAN lines, so it must be accurate. However, CAN bus typically transmits data from sensors installed on the trailer, such as air suspension pressure sensors or load sensors. These sensors estimate weight based on pressure or strain, not direct weighing. For air suspension-based systems, the accuracy is usually ±2–5% of the load.

In addition to the three functionalities, can I also read tachograph data? 

Yes, this is possible, but we encountered different implementation scenarios based on the truck model:

1. FMS connection contains both FMS and tacho data on the same bit rate, and trailer data is on the second line. In that case, you won’t have DTC functionality.

2. Read tachograph live data, but downloading DDD files will not be possible. In this case, CAN1 should be used with an alternative FMS connection to receive vehicle CAN data and diagnostic messages, while CAN2 is connected to ECAN02 for trailer data. For tachograph live data, you can connect the K-Line wire.

3. Suitable for VDO tachographs, allows you to receive tachograph data and download DDD files through the front panel via the K-Line. This approach keeps both CAN lines available for FMS, diagnostic trouble codes, and trailer data.

4. Some manufacturers have FMS/Trailer/DTC data on the same “Alternative connection” CAN line - directly on the vehicle ECU. Then one CAN line is used to get FMS/Trailer/DTC, and another CAN is used to connect to the Tachograph to get DDD files and live data.

What firmware version supports these functionalities?

03.01.02.rev.06 would be enough to have all the features. In order to get this firmware, you can contact our support via helpdesk, and they will provide it unencrypted.