Snap-on Live Training Episode 08 - Data Bus Testing and Diagnosis Part 2

[@stephenjwheeler8731]

Thanks so Very Much for the invaluable training!

[@AustinCraig-e1u]

Should a CAN bus signal look the same no matter where you check in the circuit? As an example: If I check at the DLC and then check at the abs module, will I see the same waveform?

[@troylegere6221]

Thank you for your time. Very informative.

[@eekimus]

Hello, I've been trying to investigate an issue in a 2013 Toyota Landcruiser Prado which runs a MOST Bus for audio. It thinks the amplifier is disconnected. Have installed a new, working amplifier and shows amplifier still disconnected. Have tested entire stereo wiring harness for shorts, short to power/ground, continuity and resistance. Has WUI (wake up in) and WUO (wake up out) wires which show battery voltage as required. Have you scoped the MOST lines before? Should they be 5V differential pattern like a CAN? Similar resistors in the controllers? There is 1 more wire called SLD - any idea what it is? Thanks.

[@lamboricer3743]

Wifi flashing is so stupid. I remember i had a vehicle in the shop that needed a transmission flash. My shop wifi was crappy and i couldn't flash it because the guy at the other line couldn't connect to the vehicle. So I had to tow the the dealer .🤦🏽‍♂️

[@glynfernandez1760]

Good job sir

[@ritchierich66]

Great info thanks

[@SnaponDiagnostics]

Glad it was helpful!

[@iam1smiley1]

Is it possible to know from wiring diagram, if a vehicle has fiberoptic MOST bus? How will I know 🤔 Thanks Jason and Snap-on!

[@SnaponDiagnostics]

It will depend on the wiring diagram. Some will label it as such and some will not. You would also be able to tell by the connector as it will be different than a standard copper wire connector.

[@pauldorkins5530]

Great vid btw! I had a skoda yeti with can comms issues on loads off modules! I scoped it at gateway and wave pattern was bad. Checked with m meter and had o/c! Found problem with A-post wiring which I renewed can signal was good codes cleared but using a meter it was still o/c! Please any explanation 🙏 just started using a pico thanks in advance!

[@bennylarussa8010]

Very well explained

[@jmyers9853]

i can't wait for an EMP so i can go back to points and plugs

[@kevencausby5964]

I see note about the Triton D8 needing that cable. Does the D10 also require it as well?

[@SnaponDiagnostics]

The D10 has the conversion circuitry built into the tool. No extra cable needed.

[@kevencausby5964]

@@SnaponDiagnostics Thanks for the reply!

[@wanazizul]

I measured Merc Clk200 pin 6,14 has small mV only, car has no AC, radios, power windows, steering turns wiper, seats control, except car can start and run ok. Ground pin 5,6 ok, 16 powr 12v ok, how do i check signal hi lo why it disappeared or shorted somewhere, pls help

[@kashinathhegde1617]

Tell something about EV circuits. Does these have similar bus?

[@mikeadler434]

👍👍

[@rafaelordonio1102]

Hello, do I need to disconnect the car battery first before resistance test of the obd fort?

[@SnaponDiagnostics]

Yes, you should.

[@jeffowensby5946]

Security lite came on and will not start after changing the starter what is the problem

[@One_DeepNation]

So what does CAN high and CAN low actually do? Like what’s their purpose? Is it one for communication and the other is for ground?

[@SnaponDiagnostics]

They both transmit at the same time. The control modules are looking for a differential voltage to decide if the data is a 1 or 0. If both lines are at 2.5v, there is no differential. When the high side voltage goes up and the low side voltage goes down, there is a voltage differential of 2-2.5 volts. By one line going up and one line going down, if there is any interference or a voltage spike, it will affect both high and low equally, keeping the voltage differential the same.

[@One_DeepNation]

Okay thanks. I have another question So I heard you says something about modules running a 12v…? And then CAN high is running between 2.5-4 and low is 2.5-1. So my question is where does the 12v come from or is the 12v a collective voltage? Not sure if it makes sense. Just want to know from where does the 12v comes from? And is the 2.5 or 1.0v make the 12v???