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.
ImportCar Magazine: www.import-car.com
Mitchell1: www.mitchell1.com

[@faroukkhan6777]

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

[@mikecrowther2310]

Well done brother!

[@billbled]

Great explanation - thanks.

[@user-xx1ox6qk5f]

جزاك الله كل خير

[@kjarby69]

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?

[@Acompony]

Man I wish this guy responded

[@alitehrani3415]

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

[@salta199]

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.

[@elgroso806]

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.

[@johnmitchell8925]

did you try using a different scanner

[@user-vw8ji4ve5m]

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

[@mikeh2772]

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

[@duanedonaldson2262]

The voltage is regulated near 2.5 volts, loss of a terminating resistor will have little effect on the voltage but may have a large effect on the way the pattern looks on a scope.

[@crazyharis]

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

[@duanedonaldson2262]

Not all vehicles are connected to the CAN and the DLC OBDII connector, how was you testing at the OBDII? If you hook up a scope (only, no scanner comm) to the CAN HI and CAN LOW pins at the DLC and if there is a GATEWAY involved, you will not get much action on your scope, if you monitor the CAN with your Scantool (in scan mode), the Gateway now knows its a NODE connected and it passes the CAN patterns to the Scantool Scope screen.

[@lazarvasile3333]

This is what im whant to se ...

[@JMac85X]

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

[@HerbMoore3]

Yea, I bought a $50k newer model truck, then it got hit by lightning... giant paperweight now... wish I would've bought a 1972 Chevy Pickup and cherried it out instead!! 🤣

[@JMac85X]

@Herb Moore Maybe I'm wrong but if your paying $800 plus a month for a vehicle for 8 years than why not just buy an older truck and fix it up, dump $800 month in it and the value goes up. I just don't like new vehicles, too must plastic, they look cool and have a lot of power but too many sensors and issues that can go wrong

[@johnmitchell8925]

@@HerbMoore3 Think about all the flood cars out waiting to be sold to some unsuspecting buyer

[@wishicouldsing129]

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)

[@bobdelabourer1307]

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. 🙏

[@phasorsystems6873]

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

[@racingrivalsgoblin3895]

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

[@phantom5573]

agree

[@LegendLength]

It depends on the car. You need to look at the schematic for the high speed communication bus and follow the wires in the car.