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How to Perform a Commercial Vehicle Diagnostic Test? + FAQs


Regularly performing diagnostic tests is especially relevant for commercial vehicles. Not only do they see more miles but are often on tight schedules and if the vehicle breaks down – it can cause quite a commotion for the fleet managers. Considering that a commercial vehicle downtime equals lost money but worry not, carrying out these tests can act as preventative maintenance – discovering problems before they become too severe.

So, on that note, we’ve prepared a quick guide to introduce commercial vehicle diagnostic tests.

What is a commercial vehicle diagnostic test?

A commercial vehicle diagnostic test is a series of tests, checks, and measurements carried out in one single action to determine if a component or system is working correctly within the boundaries set by the electronic control unit (ECU).

In many circumstances, an active fault code is not enough to determine the root cause of a fault and acts more as a guide to what is going on with the vehicle. This is where Jaltest comes into its own by offering a wide range of system checks and tests.

What tools are needed to perform a commercial vehicle diagnostic test?

The majority of system checks only require the Jaltest software and Testpad Extreme Pro (a military-grade workshop tablet PC) to perform these tests, on some occasions, it does require the end user to carry out certain pre-conditions for the test to work

Why are diagnostic tests beneficial for commercial vehicle fleets?

Commercial vehicle diagnostic tests are crucial to correctly identify the exact component that is causing the error code to be present within the ECU, by using the live data, component actuation & component testing – these tests can accurately identify whether a vehicle component is in good working order or faulty & needs fixing.

How to perform a commercial vehicle diagnostic test?

Carrying out the diagnostic test is relatively straightforward due to the easy-to-use interface of Jaltest software, and the in-depth instructions provided after every test. Not only does Jaltest explain how to carry out these tests, but it also delivers advice on exactly what you are looking for and how to interpret the data.

Furthermore, if a customer is still struggling to use Jaltest, we at Eclipse Automotive Technology, have the industry’s best technical support at the end of the phone – who can remotely connect to the Jaltest device and assist with any system check that is being carried out and help with analysing the results.

What are common challenges to expect & how to overcome them?

Some system checks require the vehicle to be set up in a particular way with a fair few preconditions. Nevertheless, the software displays them at the beginning of each test, which leaves the technician to ensure the instructions are followed.

Another challenge can be interpreting the data at the end of certain system checks. However, all customers have peace of mind knowing they have Eclipse’s vehicle support team on hand to assist with executing these tests.

Final thoughts

Active error codes on a vehicle are great at pointing the technician in the right direction whilst fixing the vehicle. Nevertheless, with the addition of Jaltest system checks/tests, you can be assured that when you identify the component(s) at fault – you can repair the vehicle with the confidence that this will rectify the fault.

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