CAN bus communication issues | Tech Minute

When you get a car in your shop and you can only communicate with a few to none of the modules, what do you do? Andrew Markel explains how and why you need to pull out the wiring diagram and measure resistance.

[faroukkhan]

Thank you for your time Sir, have a great day 👌

[kjarby]

Are the resistors on the outside of the control modules?

I have a reading of 122 ohms on pins 6, 14 on my truck 2016 Ford F250 Super Duty (gas)

Symptoms: flashing skid, brakes, abs, battery on dashboard lights. Gauges intermittently go off then on. Chime sound constantly and sometimes erratically more chime sounds. Headlights and tail lights stay on after ignition off and key out…eventually lights go out. Sometimes drains the battery if setting for days.

Are these resistors external to the controllers or built in the controllers?

[alitehrani]

Was great video , but terminating resistors are not always inside ecu s

[elgroso]

Hello.
I have a problem with a can bus.
No u codes.
I can communicate with all the modules but i can't get live data.
As soon as I try read the live data on any module, the scanner takes me out and display a message of no communication.
I have literally done everything.
I don't really know what else I can do to diagnose the can bus system.

[JMacX]

Moral of the story, buy something older and with less gizmos.

[vwjivem]

Clients landrover lr4 diagnostic says no communication between audio an cluster an can bus.The radio does not come on.

[bobdelabourer]

As an engineer and a common sense thinker this is a design flaw. At least have a back up in case any of these two wires get shorted to ground or together. Divert information packets via a secondary line such as to "limp" ones car to an automotive technician. 🙏

[salta]

Hi, I've been searching the internet for hours looking for a solution. I have a problem with the cambus. Steering wheel controls don't work, and when I turn the key the radio won't turn on. gives me error (U2101-00 canbus maximum configuration list not programmed). I tried unplugging the battery for 1 hour but the problem is still there. I was wondering if you had any idea what this error is and possibly how to fix it. I hope you answer me since the video is years old. I thank you in advance.

[mikeh]

Nice video. Getting back to OHM`s law how ever... you will be too high on voltage.

[crazyharis]

Super video ! I had 5 modules and ecu defect. But i still have no communication with the obd2, van you help me ? Thanks

[EpicGamingIndustry]

What type of damn hell was this I need to see you point this shit out on the car

[phasorsystems]

Build your electrical circuits on the go! scan circuit solver on the playstore!

[wishicouldsing]

2003 f350 6.0 diesel only uses canbus for the ficm only. Ford protocol is used for everything else. Am I wrong? My can bus has 2.45 volts on both high and low wires. I unplug the ficm and the voltage comes up on the high side and drops on the low side. Is the ficm bad? Truck runs, but has low power and no codes. Ford protocol is OK. I use a breakout box to monitor the system(s) voltages. Rebuilt ficm, but both do the same thing, (old one and new one)