CAN Network Diagnostics

Are you having difficulty diagnosing communication problems on a vehicle?

A Snap-on® platform can help you to overcome the challenges and get to the root cause of the problem.

You will need to use the lab scope function, because that’s the only way to test a vehicle’s CAN network, but once you’re hooked up your tool will tell you what you need to know.

Using a Snap-on VERUS® Edge car diagnostic tool as an example, connect to a DLC break-out box using channels 6 and 14, which will be the same whatever you are working on as all CAN network vehicles terminate on pins 6 and 14 as standard. Connect the ground to pin 4 or 5.

Set both channels on your lab scope to a 10v scale to give yourself a large, clear window in which to analyse the data, then set the time base down to 100 micro-seconds.

Pause the scope to take some measurements. The squares shown on the graph illustrate when data is being transferred within the vehicle but your main interest will be in the voltages being recorded.

Where the yellow and green lines meet you want to see a reading of around 2.5v then when the lines separate, during data transmission, one should go up by a volt and one should drop by a volt if everything is operating correctly.

Setting the channels to a 10v scale has the added advantage of making it easier to see when there is an issue – if one of the lines drops to zero then there’s a bad ground or ground issue, while if the voltage rises outside of the expected readings then there is a power problem.

So as you can see, the lab scope option is a straightforward way to help diagnose communication on CAN network vehicles and should always be considered.

To receive our Technical Focus articles direct to your e-mail inbox every month, simply enter your details in the sign-up box on the right side of this page.

See more articles on our News Center page.

Got Questions?

Get Answers Here
Car & Light Truck Diagnostics

Send e-mail
(800) 424-7226

Heavy-Duty Truck Diagnostics

Contact us here
(800) 311-5452

Request Product Information

Sign Up For Our Technical Focus Articles


Each month, Snap-on produces a Technical Focus article based on real-world case studies by our team of experts. If you would like to receive this articles emailed directly to you, please enter your details on the form below.


Email address: 

Email addresses will be used to keep you updated about future Snap-on product releases and developments. If you do not wish to receive any mailings from us other than the Technical Focus articles, please click the box below.

Opt Out


Snap-on Diagnostic Tools and

Repair Information

Snap-on is a trademark of Snap-on Incorporated.

All other marks are marks of their respective holders.

©2019 Snap-on Incorporated. All Rights Reserved.

Got Questions?

Request Product Information

Online Product Help Here

Contact Diagnostic Customer Care

Send e-mail

(800) 424-7226

Mon - Fri 6am - 5pm PST


Product Registration:

• US     • Canada

We have placed cookies on your computer to give you the best possible experience with our website. These cookies are also used to ensure we show you advertising that is relevant to you. If you continue without changing your settings, you are agreeing to our use of cookies to improve your user experience. You can click the cookie settings link on our website to change your cookie settings at any time.
Privacy Policy