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What Is A PNDB On Freightliner? (Explained For Beginners!)

As a truck owner, you should understand every part and system of your truck and how they function. For beginners, it may seem daunting to familiarize yourself with the most complicated ones. But no worries, we got you covered.

This article will teach you more about your Freightliner vehicle power distribution, particularly PNDB, and what is its function in your truck.

Here’s a short summary of what a PNDB is on Freightliner:

A PNDB or Powernet Distribution Box on a Freightliner distributes and fuse battery power to many of the vehicle loads such as the SAM cab, SAM chassis, powertrain PDM, and other keep-alive circuits. PNDBs are typically found in EPA10 vehicles and newer models.

What Does a PNDB on a Freightliner Do?

A PNDB distributes battery power to the truck’s loads and keep-alive circuits.

The PNDB in a Freightliner contains three MIDI fuses, four ATO fuses, relays for the truck’s engine, transmission, and the ATS or the after-treatment system.

In some cases, a vehicle can have a secondary PNDB to source power to other systems or parts of your truck.

These systems include fleet management communications, shore power inverter, trailer end-of-frame connection, and bodybuilder PDM, which contains fuses and relays used for body equipment installation.

Do all Freightliner Trucks have a PNDB?

Typically PNDBs are found in EPA10 vehicles or newer. These Freightliner models will have a PNDB since it is responsible for the electrical power distribution of the vehicle’s battery power.

Some features may malfunction if a Freightliner truck encounters issues on its PNDB, such as poor fuse retention on the circuits.

If this happens, it will cause irregular operation on the devices that the PNDB supplies power into and can also overcharge the alternator.

How Many PNDB does Freightliner Have?

There is only one PNDB in a Freightliner to work on the power distribution. However, a secondary PNDB may also be possible.

If your Freightliner truck has only one PNDB, it can already distribute the necessary power to engine and transmission fuses.

Another PNDB exists to supply power to other systems or machinery of your truck. It includes fleet management communications, shore power inverter, trailer end-of-frame connection, and bodybuilder PDM, which contains fuses and relays used for body equipment installation.

Where is the Freightliner PNDB Located?

You can find the PNDB of your Freightliner truck in the engine compartment, somewhere on the front wall, and just a few inches away from the steering column.

Other engine power distribution components within its location include the Powertrain PDM (PT-PDM), inline fuse, auxiliary PDM, and the SAM chassis.

At first glance, you may find the entire components of the PNDB confusing. But since each fuse has a cover, you can quickly identify its circuit.

What are Typical Freightliner PNDB Problems?

Some common problems you may encounter in PNDB modules are poor fuse retention and intermittent operation of the parts supplied by the PNDB circuits.

Aside from that, a failing PNDB can also cause an alternator to overcharge, even for those that can self-regulate. A self-regulating alternator can replace the battery voltage reading.

If there is a misplacement on the keep-alive circuits of the PNDB or if they start to fall out, replacing the PNDB is the best solution you can do.

Freightliner PNDB Troubleshooting

If you encounter any problems concerning the electrical power distribution of your Freightliner truck, it may or may not be the PNDB that has a problem yet.

To troubleshoot a PNDB, check all the batteries and cables first, as there might be corrosion.

If you currently have your truck’s PNDB module replaced, you can try replacing the silicon bead across the top and on its sides. This problem is quite frequent with the Freightliner Cascadia models.

To ensure that your truck is always in its top shape, you should also consider replacing the PNDB several times a year. If you often experience a weak or no clicking sound when you switch on and off the truck, that is also an indication for replacement.

What does Freightliner PNDB LED Light Signals Mean?

The power distribution modules or PDMs also have display panel functions and LEDs to indicate the PNDB status of your Freightliner truck.

Freightliner PNDB Light Blinking or Flashing

It is normal to see blinking or flashing lights on your truck’s display panel for you to notice the issues or condition of your vehicle right away.

Typically, these lights may often indicate problems with your truck. However, there is a specific color that may appear. Each of these colors has its unique meaning.

For example, a green light refers to the utility or the Shore Power Mode. If it is solid green, then it indicates a fully charged battery. If it starts to flash, it means the battery is charging.

Another color you will also see on display is yellow. It tells you about the battery or the Inverter Mode. If it is in solid yellow light, the battery is in use to supply AC power.

Once it starts to flash, the unit is currently in inverter mode. It already detects the AC Shore Power and transfers it within 20 seconds to Shore Power Mode.

Freightliner Cascadia PNDB Red Light

Similar to other devices, a red light indicates alarming or severe problems. It is identical to the PNDB display light of the Freightliner Cascadia.

A red light means a fault condition exists in the PNDB and other PDMs or the truck’s electrical power distribution system.

Once you see a red light on the display, go over your truck’s owner’s manual to check the fault code’s information and the proper way to troubleshoot it.

Thus, it is necessary to always have the manual with you so you can find out immediately the current condition of your truck and if it is still safe for you to drive.

Can You Bypass the PNDB on a Freightliner?

It is possible to bypass the PNDB of a Freightliner if you want. However, you should refrain from doing it if you are not entirely familiar with PDMs and Freightliner trucks’ electric power distribution systems or do not have the right tools since you may ruin its fuses and circuits.

To bypass the PNDB of a Freightliner, turn off the engine first and open the hood. Look for the PNDB fuse box. You can find it on the left area of the sheering shaft. You will see a fuse box with two yellow locks and a flashing red light.

Open the cover and remove the 30 amperes green mini fuse. If you are unsure what that is, look for the ACM label, and that’s it.

After removing the fuse, close the fuse box and the hood. Try to start the engine. You will then see a stop warning sign, but you should ignore it.

Search the dashboard for the “engine override” button near the regen button. Hold it down and drive the unit.

When Should You Replace the PNDB in Your Freightliner?

The best indication to replace the PNDB of your Freightliner is when you already experience poor fuse retention and intermittent operation of the parts supplied by the PNDB circuits.

To replace the PNDB, you should park your truck on a flat surface and shut the engine down. Do not forget to set the parking brake.

Look for the PNDB at the cab front wall above the main ground junction block. Once you see it, disconnect all the batteries attached, including the auxiliary battery bank, if your truck has one.

Inspect the keep-alive circuit and cab load disconnect switch (CLDS) connectors as you open the hood. Ensure that the plugs are in unused connector cavities. Install the missing plugs to seal the connector.

If you have an equipped cab load disconnect switch or CLDS connector, disconnect them and the keep-alive circuit connector. Using a flat-head screwdriver, push the red locking tab up, then press and release the tab. After that, you can now remove the connector.

Next, disconnect the power cables from the PNDB. Before removing the PNDB itself, remove the two mounting nuts first.

After removing the PNDB, position the new PNDB on the front wall and attach the two mounting nuts, the keep-alive circuit connector, and the CLDS switch, if you have one.

Connect the power cables and all the batteries, including the auxiliary batteries, if equipped. Once you connect all the necessary equipment to the PNDB, you can now close the hood. Finally, your Freightliner truck has its newly-installed PNDB.

How Much Does a Freightliner PNDB Cost?

Since it is important to regularly replace the PNDB of your Freightliner truck to keep its performance, you need to know how much it will cost you.

On average, a PNDB amounts from $250 to $300. The price will still depend on some other important factors. You may also add more for the replacement cost and other necessary maintenance your truck needs.