L5P CAN Bus Plug Kit: What It Does, What It Fits and What Else the Delete Needs

What Do CAN Bus Plugs Do on an L5P Duramax?

The L5P is a 6.6L V-8 turbo-diesel.^[3] The electronic engine control unit is the central controller and heart of the engine management system.^[2] The CAN bus plugs provide a closed signal back to the ECM so it reads correctly after the delete.^[1] The plugs are required for delete tuning on the L5P.^[1]

Here's the thing — on this engine, the wiring side of a delete matters every bit as much as the pipe. Let's break it down: what the ECM is listening for, why an open connector is trouble, and where the plugs land in your build.

What the ECM expects to hear from the exhaust side

Think of the engine computer as the foreman on a busy job site. The electronic engine control unit controls the fuel supply, air management, fuel injection and ignition.^[2] The control unit is also able to control the exhaust system as well as to integrate transmission and vehicle functions.^[2]

Connectors are used to connect control units, sensors and actuators with the cables of the vehicle electrical system.^[2] Picture each one as a phone line running back to the foreman's desk. Cut a line, and he's left waiting on a call that never comes.

Why an open connector is a problem after the delete

A lot of guys assume the job is finished once the new pipe is bolted up. Here's where that goes sideways. The plugs are made for use with aftermarket exhaust systems or delete pipes.^[1]

That step is easy to overlook when the shiny parts are sitting on the bench. Leave those connectors hanging and you're asking the ECM to make sense of a conversation with half the voices missing. That's not a puzzle you want to be solving on the dyno the night before an event.

Where the plugs fit into a delete build

Plan the plugs in alongside the tune, not as an afterthought once the truck is back on the ground. Treat them as one job and get both sorted before the first wrench turns. That leaves the obvious next question: does your truck make the cut?

Which L5P Trucks Does the CAN Bus Plug Kit Fit?

The engine and the model year decide it. Fitment covers 2017, 2018, 2019, 2020, 2021, 2022, and 2023 Silverado and Sierra 2500/3500HD trucks with the L5P Duramax.^[1] The Duramax L5P 2017-2023 DELETE SOFTWARE fits the L5P from 2017 through 2023. The Tuner Harness Plug Kit fits the 6.6L LML Duramax and the L5P.

That's a tidy lineup, but your truck is the one that has to match it. Which bracket does yours sit in?

Reading the engine and model year off your own truck

Walk out to the truck before you go any further. Check the engine badge, then the model year, and write both down. It takes a moment, it beats guessing, and both come up again when it's time to install.

Silverado or Sierra: what the plug kit covers

The L5P CAN Bus Plug Kit is for 2017–2023 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD with the 6.6L Duramax L5P.^[1] Bowtie or GMC badge on the grille, you're reading from the same page. Heavy-duty workhorses, every one of them.

Where the related parts line up with the plugs

Running a Cab & Chassis truck? The Tuner Harness Plug Kit does not fit Cab & Chassis trucks.^[4] Fitment is for 2011–2016 LML and 2017–2023 L5P Duramax pickup models only.^[4] It won't fit LMM, LBZ, LLY, or LB7 Duramax generations — the connector profiles are specific to the LML and L5P.^[4]

Here's the whole lineup side by side, so you can see where each part lands.

What Comes With the CAN Bus Plug Kit?

The L5P CAN Bus Plug Kit costs $119.00. This kit is sold separately for owners who just need the plugs on their own.^[1] For which plug goes where, call (888) 830-2588 or email sales@thedieseldudes.com and the team will walk you through it.^[1]

Now, the job itself. The plugs go in place of the NOx and DEF module connectors.^[1] The L5P CAN Bus Plug Kit is required when you remove the DPF (Diesel Particulate Filter) and DEF (Diesel Exhaust Fluid) systems.^[1] Want to know exactly which plug lands on which connector before the box shows up? That's what the phone line is for.

If you bought a full delete kit

Do you need this kit if you already bought a full delete kit? Here's the good news, and it might keep some cash in your pocket. If you already bought a full delete kit from The Diesel Dudes, these plugs are included in that bundle.^[1]

Dig out that box before you double up. Nobody needs a spare set of plugs rattling around the toolbox.

If you only need the plugs

Maybe the pipe came from somewhere else, or you're finishing a build a buddy started and the plugs never made it into the box. Either way, it's a small part doing a big job, and that's real bang for your buck.

Who to ask before you start

Don't guess at which connector gets which plug. A quick call before the truck goes up on the lift beats an afternoon on your back under it.

What Else Does an L5P Delete Need Besides the Plugs?

The plugs are only the start of the parts list. The L5P delete software is priced from $1,799.00 to $2,199.00. Eight tuning credits are required.^[5] The Tuner Harness Plug Kit caps off exposed OEM EGR and DPF harness connectors after a delete.^[4] The Tuner Harness Plug Kit is priced from $169.00 to $189.00.

Similar names, different jobs, so don't let them fool you. Here's how each one earns its spot.

The delete tune and its tuning credits

Start with the tune, and count your tuning credits before you check out. You can add them to your order or use credits you already have.^[5]

Leftover credits from an earlier build are money you've already spent. Put them to work.

Shift on the Fly on pickup models

You get the GM/Duramax L5P software files with Shift on the Fly functionality for pickup models, so you can change your power level right from the steering wheel controls.^[5] That's a game-changer between rounds, with your thumb doing the work right there on the wheel.

Shift on the Fly is a pickup-only feature.^[5] Running a Cab & Chassis L5P? Ask the team before you count on it.

Capping the unused EGR and DPF harness connectors

When you pull the EGR (Exhaust Gas Recirculation) and DPF systems, the factory wiring connectors that fed them don't go anywhere.^[4] Out of sight shouldn't mean out of mind. Leaving them open is like leaving the trailer windows down in a rainstorm.

Each cap plugs directly into the OEM connector with no modification — easy to install, no tools, no guesswork — and leaves your engine bay with a clean, finished look.^[4] Shipping is included in the price.^[4]

What Should You Expect During Installation?

The can bus plugs must be installed. A 2017-2019 L5P Duramax guide covers can bus plug location and install. A 2020-2023 L5P Duramax guide covers can bus plug location and install. After you order, we email a vehicle information form to collect your VIN, year/make/model, and ECM serial number.^[5] A Windows 10 or newer PC is required to load the custom tune files.^[5]

Buckle up, because a little prep here saves a lot of grief later. Let's take it in the order you'll actually live it.

Finding the right guide for your model year

Remember the model year you wrote down earlier? This is where it pays off. Pull up the guide that matches your bracket and go through it before you touch a connector.

All delete kit instructions will be sent to you via email post purchase. Keep that email somewhere you can find it in the pits, not buried under a pile of receipts.

What to have ready before the tune is built

Your custom tune files arrive within 3–5 business days of an accurate submission.^[5] The key word there is accurate, so double-check every entry on that form before you hit send.

This software is built to order and not eligible for refunds, so reach out before buying if you have questions.^[5] Not sure about an entry? Pick up the phone first. A quick call beats a tune built for the wrong truck.

The computer you load the tune from

Check the laptop before tune day, not on it. Mac and Linux are not compatible.^[5] If the only laptop in the trailer is a Mac, sort that out now rather than at the track.

What to check when you finish

Once the plugs are in and the tune is loaded, take a slow walk around the truck with a flashlight. Look over every connector you touched and make sure each one is fully seated, not just resting in place. A loose plug found in the pits beats one found halfway down the track.

Which Parts Should Your L5P Delete Order Include?

For a 2017-2023 L5P truck, start with the L5P CAN Bus Plug Kit. Pair the plugs with the L5P delete software on a 2017-2023 L5P. On an L5P pickup, add the Tuner Harness Plug Kit. Over time, unprotected connectors corrode.^[4] That corrosion can spread to nearby wiring and throw phantom codes that are a pain to diagnose.^[4]

The order to buy in

Let's rank them, because a parts list without a verdict is just a list. The order above is the one we'd build it in, start to finish.

Line the plugs up before the tune files show up, so the truck is ready the day they do. Then the caps go on last, once the old hardware is off and you can see every connector you're dealing with.

Why the harness caps are worth adding

Phantom codes are the worst kind of headache, because the truck acts up and nothing points to why. This kit seals all of it off before that starts.^[4]

Skipping the caps to save a few bucks is like building a race motor and leaving the oil fill cap off. That's a corner nobody should cut.

Checking your engine before you order

Not sure what's under the hood? Pop it and look before you check out. A wrong guess at the engine is the one mistake none of these parts can fix, so make it the first thing you confirm.

Body style matters for the caps, too. The Tuner Harness Plug Kit does not fit Cab & Chassis trucks. Running one? Cross that line off the list.