We discussed last month how to find customer access for battery and switched power in the cabs of NGP (New Generation Product – T680, T880, and W990) along with 1.9M Cab (T660, T800, W900) trucks. This month let us look at installing an ELD (Electronic Logging Devises) into these two platforms.
Kenworth runs multiple CAN (Controller Area Network) systems in both platforms. NGP trucks have migrated to the latest control system of CVMUX. Two modules control all cab and chassis functions using modules such as the SCM (Standard Chassis Module) to control functions like lighting and electric over air systems. 1.9M cabs run NAMUX 3 or 4 system depending on the year. NAMUX systems run a single control module with a chassis module, again year dependent.
Kenworth has taken the stance if you plug into their network and your addition causes fault codes they are not responsible. This includes plugging an ELD into the 9 pin and applies to NGP trucks. We have had several cases of the ELD causing noise on the CAN communication lines setting random fault codes; it is something to take seriously.
Let’s take a second and discuss CAN networks and their functions. You can think of CAN networks as high-speed communication lines where modules talk to each other at either 250KB/s (Kilobits) or 500KB/s speed. These CAN networks follow SAE J1939 standards and have two 120-ohm resistors making circuit resistance 60 +/- 3 ohms between the twisted circuits. These modules relay information in almost real time using varying voltage signals. One line is CAN HI where the voltage is pulled up and the other is CAN LOW, the voltage is pulled down. HI and LOW are mirror images of each other when measured with an oscilloscope as shown below. Most CAN faults occur when data is missing that a module is looking for and does not see it for one second. Speaking as a technician, intermittent CAN faults are the hardest to troubleshoot. We can spend hours trying to locate the fault and sometimes never do.
CVMUX started in the NGP product around October 2018 and was order dependent. Now every NGP is running this system, let’s look at the recommended procedure for connecting an ELD. Kenworth has provided a dedicated connector for customer hookup where data is needed, the RP1226 connector. It is located at the fuse box, lower left under the steering column. Kenworth provides the mating connector and pins in the glovebox of every new truck. Most ELD manufactures have connectors prewired and ready, you just need to specify you have a PACCAR RP1226 setup when ordering. The K-CAN is 250kb/s and the S-CAN is 500kb/s and are setup in a way not to interfere with module communication.
We have installed ELD’s for customers that are moving an older ELD that hooked to the 9 pin to a new NGP truck. In these cases, we used the connector and pins Kenworth provided. Just cut the 9 pins off the old cable and wire in the connector using the diagram below. Be sure to wire CAN HI and CAN LOW correctly, the polarity matters. For 250kb/s systems, pins C&D will be the CAN wiring with pin C being the HI and D being the LOW. Pin A will be ground and Pin B will be power. The rest of the pins are not used. For 500kb /s systems, C&D will be 500kb/s CAN and F&G will be the 250kb/s CAN. Get with the ELD provider for more information in regards to your setup; don’t let them tell you to just hook to the 9 pin on your new NGP truck!