There’s a little-studied phenomenon, known as the “cross-your-fingers-and-hope-to-God-it-works” event, that occurs among the small but passionate population of people who prefer to build their own personal computers. It takes place when swapping out one part, such as the graphics card or the hard drive, for another part. The user is sure it’s compatible. They’ve checked 1,000 times. They’ve scoured the forums to see what has worked for others. But when it comes time to boot up for the first time with the new part, no matter their level of confidence, the phenomenon always happens. Because computers are finicky, delicate little flowers and you never know when they’ll defy you.

As today’s trucks are essentially giant rolling computers, many a fleet manager has found themselves experiencing this very event following even seemingly simple maintenance. The truck’s ECU is vital to controlling the engine and other component functions, and it is not uncommon for one part to be swapped for another, only for the fleet manager to later realize with horror that certain accessories have stopped working and the telematics data isn’t being pulled correctly. Or, worst-case scenario, critical trucking components are no longer responding to the driver as expected.

Here’s the good news: The experts say with the right resources and education, fleet managers can avoid this phenomenon altogether.

Why does this ECU issue happen?

According to Scott Bolt, Noregon vice president of product management, the most common reasons a truck might have this happen include:

• Components were replaced in a manner that did not follow an OEM’s process and procedure. (This can cause cascading problems that we’ll discuss later.)
• A common assumption is that most truck components are “plug and play” solutions, but this is often not the case.
• Attempts at cost savings lead to purchasing the wrong component. “This often means replacement components are purchased outside of OEM sources, such as a junkyard or other third-party resellers, who compete at better price points. Using a simple online search to purchase a replacement component brings risk of misrepresented part numbers, which can cause component incompatibility when installed,” Bolt says.
• Fleets, aftermarket shops, and independent truck owners are less likely to be equipped with the necessary tools or equipment OEM dealerships have. “When it comes to tackling certain component replacements from start to finish, having the right tools and information are critical in being able to recover from and resolve issues that can arise during service,” Bolt says.

What are the potential consequences of this ECU issue happening?

For certain components, each OEM has their own specific process and procedures that must be followed during maintenance to prevent unintended consequences, Bolt says – including consequences affecting warranty coverage.

“A lifeline to many fleets that run brand new trucks is the warranty process,” he says. “These fleets need to be careful when it comes to acquiring parts and components from anyone other than the authorized dealer.”

Sidestepping the process can lead to the aforementioned cascading set of problems. Bolt gives three examples of how things can quickly get out of hand.

1. Diesel particulate filter (DPF) replacement – When replacing a DPF, certain OEMs can require engine ECU learned data be reset, the replacement component serial number programmed into the ECU, as well as providing an internet-based update of the new part number to an OE’s central systems.

Replacing only the DPF, either with a new, used or similar unit, results in incomplete DPF service, which could affect future warranty coverage eligibility, cause premature failure of the replacement DPF or even damage more expensive downstream components.

2. Instrument cluster replacement – For replacement of an instrument cluster, many OEs have tools, processes and procedures for changing or reprogramming the replacement to correctly interface with the build spec of the truck and to offer seamless reprogramming of historical data such as mileage.

Incorrectly reported or reprogrammed mileage on the replacement part can spell issues with vehicle service centers, warranty eligibility, misalignments with telematics service provider metrics and reporting history if they happen to source vehicle mileage based on what is programmed inside the instrument cluster ECU. This can also be an issue when it comes time to sell the vehicle.

“Seeing a truck that is two or three years old with fewer than 100k on the clock usually makes potential buyers cautious,” Bolt says. “If mileage cannot be accurately determined, asset value could become unclear.”

Replacing an instrument cluster with one that looks close is a common occurrence, Bolt adds. These, having not been reprogrammed, or having been acquired from a non-OE source, have the potential to incorrectly interface with the rest of the vehicle, rendering certain accessories or even critical functions unable to work.

3. Transmission replacement – When replacing a transmission, certain OEMs can require a TECU learn data reset, a relearn procedure be executed, or special service routines that need to be followed to allow the new unit to enter service smoothly. Some even use their tool to report the new transmission control module (TCM) information to their central systems for warranty purposes.

“Simply replacing the transmission without following OEM procedure – or replacing the unit with a version that is just ‘slightly’ different – has the potential to destroy the replacement unit and damage other components,” Bolt says. “Not following processes or installing incorrect parts also directly impacts the warranty standing of the transmission and other related driveline/powertrain components.”

How can a fleet make sure this ECU issue doesn’t happen?

Knowing the service capabilities of the shop maintaining your fleet is key, Bolt says.

“If a technician is replacing a component that has a four- to five-figure price tag, it is imperative everything is done correctly. There are usually very specific processes and procedures that accompany such expensive components,” he adds.

Some fleets are able to equip their shops with the same specialty tools and equipment the OEM dealerships have, while for others, that may not be attainable.

“In this case, fleets must feel comfortable recognizing when to say, ‘No, we are not equipped to handle this task,’” Bolt says. “It may be a difficult decision to turn away work you want to attempt yourself, but in cases where resources are lacking, you can save yourself time and money by being honest and knowing your limitations. There is nothing wrong with this. Otherwise, you risk hurting your own bottom line and, potentially, your reputation if you attempt service and are unable to properly complete the job all the way through.”

Bolt recommends a fleet manager ask themselves three questions to determine if their fleet is capable of handling the replacement of a particular component.

First: Does the fleet have access to technicians who are well educated and experienced?

“Most shops have those ‘go-to guys’ who are extremely experienced individuals and are relied upon for their knowledge. Asking them for advice about a particular component replacement process can help when it comes to identifying times where special processes and procedures might be required,” Bolt says. “If they feel comfortable performing a task, chances are you might be equipped to handle the job from start to finish.”

Second: Does the fleet have access to OEM-level service information for the vehicle or component in question? If yes, referencing this material will be able to tell the fleet manager if there are any special requirements around replacement of the component. If no…

“Stop here, save yourself additional time spent head scratching, and gather the correct service information up front. You need this,” Bolt says. “Consider investing in an interactive maintenance guide such as NextStep Repair that provides repair instructions for all the makes and models in your fleet.”

And third: Does the fleet have access to all the required special tools or equipment mentioned in service information related to the component being replaced? If so, the fleet is probably well equipped to replace the component. Check to make sure any third-party tools have the capability or support in place to allow the fleet to succeed in replacing the component.

If the fleet doesn’t have the tools required to replace the component, handling the job in-house is not recommended, Bolt says.

“If you answered no to either question two or three, then you take the risk of leading your technician down a black hole and not being able to successfully handle the situation, potentially releasing a vehicle back into service that has not been repaired correctly,” Bolt says. “The effects of this quickly cascade across many different aspects that most do not realize until it is too late.”