CAN Bus Quick Check With Multimeter | CAN Bus Diagnostics | Mechanic Mindset

[@slimbrady7512]

I was always taught to disconnect the control units before a resistance measurement as to not potentially backfeed them with the small amount of voltage the multimeter sends during the resistance measurement.

[@MechanicMindset]

For sure, on normal components like injectors it’s important to disconnect the ECU or you measure the resistance of the ECU too. CAN Bus is a little different, you do however need to make sure the network is asleep or the battery disconnected 👍

[@shaunblakemore7150]

Great video, just got a uscope from aes wave just learning it, thank you for your time to make these videos 😃

[@MechanicMindset]

That’s a great little tool! You’re welcome, glad you are enjoying the channel 👍

[@CarsExposed]

Interesting to see the videos with the multimeter so far I’ve only used the oscilloscope to test CAN network 👍👍👍

[@MechanicMindset]

Give it a go!👍

[@CarsExposed]

Mechanic Mindset I will indeed 👍

[@nickayivor8432]

KNOWLEDGEABLE Mechanic Mindset Thank you very much helpful video 👍 Mechanic Mindset From Nick Ayivor from London England UK 🇬🇧

[@TheCarManUK]

This video is my favourite one so far. Love this east to follow guid. I have a question, if you had a short on this circuit or model, would you see it with a thermal imaging camera do you think?

[@vw_mods_4711]

Hey buddy, started binge watching your videos, some great information! I am just a hobby mechanic but get stumped when the scan tool starts talking about signal to high or to low 🙃 but through watching a few of your videos I have learned why that may be. Think I will join your paid content. Just wondering what scope to get? not going to use it much was thinking the Owon handheld as it’s a nice all in one. The most I will do with it is probably check sensors. I have 2 faults on a Volvo c30 at the moment additive dosing module signal faulty and fuel level sensor faulty signal. It would be nice if I could figure out how to diagnose this by watching your content. And stop hitting the car with the parts cannon. Just got a breakout box and I have a multimeter so will start with that. But if you had any recommendations it would be appreciated.

[@MechanicMindset]

@@vw_mods_4711 Hi, that’s great! The Pico 2204a is a real powerful bit of kit for the price. The Owon is nice and handy; the settings are a bit fiddly to use, but it’s quick for small checks. 👍 I think you’ll really enjoy what we have for learning!

[@TheGibby3340]

Nice. Clear delivery. Cheers

[@MechanicMindset]

TheGibby3340 Cheers!

[@Enares]

Nice one dude fantastic video 👌

[@philomalley594]

Nice video! I have an audi A3 cabrio 8P7 with some electrical faults. Basically the rear left tail light, hood and passenger door electrics arn’t working. I replaced the BCM module and the problem still exists. After watching your video I checked the CAN high and LOW on the OBII connector and the both read 2.5v which leads me to believe they are shorted together. I haven’t read the codes as I don’t have vcds or anything like that, but do you think I need to clear the codes first as I did have a defective brake light too which I have resolved. Where would you recommend I look next as I have checked the wiring from the BCM to the cluster and the resistance is 0ohms. Also the light cluster works on the right hand side! Could this al be caused by a damaged loom in the passenger door. Although when I peeled back the gaitor there was nothing obviously! Appreciate any advice you have. Cheers

[@mrt-ee1zn]

Hi, should measure same voltage at obd2 connector port also ? Thanks

[@MechanicMindset]

It depends on vehicle. Not in this car

[@mechanicandskills7215]

Thank you for this video.. Was this test with key on engine off Or key off modules still awake ?? thanks cheers

[@MechanicMindset]

Hi, most of the tests are done with key on engine off, modules awake. This car sleeps after a few minutes and no activity on PT CAN. Thanks!

[@mechanicandskills7215]

@@MechanicMindset Thank you so much for your reply just beginning to yous a oscilloscope i enjoy your uploads great work ....cheers

[@vicky-nc3to]

Good stuff, please keep uploading

[@MechanicMindset]

Thanks for watching. For sure, more to come! 👍

[@SynapticIllusion]

Thanks 🙏🏼 I found this super informative 👍🏼

[@MechanicMindset]

Glad you’re enjoying the channel! Do you have some CAN Bus trouble?

[@SynapticIllusion]

@@MechanicMindset A little bit of trouble trying to find a switch wire for the radio on/off with the ignition. I later realised it’s operated on the CAN and with the addition of a decoder box? Or maybe analog/digi converter? (I’m unsure of the terminology) It’s now working as normal. We have a reversing camera on it too... I notice the guide lines move with the steering wheel when your backing up. So I figured there’s a bit more to this CAN business than just an ON / off type switch. I was aware the engine sensors were CAN. It’s all really interesting! I’m super grateful for the information your putting out! 👍🏼

[@Amg641]

Hi great video! I have a no crank no start issue CAN C and CAN B i found water damage i have repaired both connectors with no luck cranking. I have tested it the way you have i have similar readings on CAN C but on CAN B my voltage can hi is 0.72 and can lo is 4.4v please advise me

[@MechanicMindset]

Hi, best try and look on a scope; this sounds like low speed CAN and the voltages are different to high speed 👍

[@Amg641]

@@MechanicMindset thank you

[@Amg641]

@@MechanicMindset can i use speaker wire to rewire CAN wires?

[@MechanicMindset]

@@Amg641 It’s ok, I would 👍 as long as it’s similar to what’s already fitted

[@billytremoloband7456]

As per usual a great informative video ! Bit of a can diagnosis/ module test question for you, I have a 2014 Mercedes Vito 2.2 blue efficiency that goes into reduced power mode but rectifies it self when the ignition is cycled with no fault codes when scanned apart from communication with clock cluster and battery monitoring, it also has no stop start working! At can high/low at the dl16 it’s reading 60ohm but no can signals until I disconnect the fuel pump control module but then I’m only getting a can low signal....! Other thing to note is the fuel pump control module is connected to the ignition switch as well as the dl16 can high / low being connected to the ignition switch ....! Very much 🤷‍♂️

[@MechanicMindset]

Glad you enjoyed the video! Sounds like a fun job you have there! I would probably try measuring the signals at the module. Also, if you can read codes from the modules (they are communicating), the CAN is probably ok. See how the whole car shuts down when I drop CAN out, it won’t even start. Limp mode is usually something related to the engine (or related systems like fuel), rather than CAN. I would probably start looking at vitals like fuel pressure, boost pressure, air mass etc. Strange you have no codes, try a different scanner. I’ve had that before, one reader doesn’t pick up a code but another does. Start Stop has many reason why is wont work (inhibitors), like battery voltage/condition. Happy fault finding!

[@billytremoloband7456]

Mechanic Mindset On the off chance would you think having either my egr or throttle body disconnected could cause the can high to go down as both of them are can driven and with either I have full power but with the engine light on! I’m currently trying to plug the egr back in but it’s literally impossible with the om651 engine when fitted in a Vito van as the fuse box is about an inch from the intake manifold 😡😡😡 no bother in an e class or c class with the same engine! I was planning tonight to reconnect the egr but disconnect the pump module and recheck the can lines but after spending 2.5 hours at it and burning/ skinning two of my left hand fingers I think it’s mabey to call it a night and try again later in the week when my fingers have heeled up ...! And they say Jlr vehicles are tight / complex to work on.........!

[@billytremoloband7456]

Mechanic Mindset I’ve also tried 3 different scanners launch , autel and snap on and they all give me just communication faults between battery monitoring and clocks but I seem to have lin signal at battery , van network at Sam unit and can and van signals at the clocks and can at the ecu when not running! Only other thing is I got an after market ignition switch fitted going back along about a year ago which by the auto data wiring diagrams appears to be connected to dlc and fuel pump control module

[@billytremoloband7456]

Mechanic Mindset I just did 1 more check there while the going was good and with the battery disconnected both can high and low at the dlc appear to be 10k ohm to ground does this sound about right?

[@pantelis241]

Great Video, thank you 😊

[@triplextriplexxx8225]

nice can you do this to test is certain module on kcan network faulty ????:) thanks for giving out tutorial on picostope i ordered one for myself for amazon for 95 gbp

[@MechanicMindset]

Good to hear, it’s a great tool! This voltage will not be ok for K-CAN, unless it’s newer car. They will be different but I can’t remember right now. Most K-CAN on a vehicle this age is low speed

[@Sigspearthumb1]

Im confused, if you have resistance on the canbus when grounded, doesn't that mean there is a short to ground?

[@stevenhillburn3172]

I am hoping you scroll through comments because I need help from someone. I have a 2011 VW CC Sport. Using a VCDS cable, I have no communication with any module. Car won't start, dashboard lit up like a Christmas tree. I have access to all areas of main wiring harness and have located all 3 can bus networks splices. VCDS times out and says no comms with gateway. I'm on my 3rd gateway module so I do not believe it's the problem. Plus I CAN communicate with the gateway (J533) off the car and on the bench. IT IS coded correctly. What I've noticed is I'm getting over 10v on org/black & org/brn wires from gateway to OBDII port. If I disconnect the gateway, voltage on those wires at the OBDII port go away. Plug gateway back in and voltages reappear. I'm lost on why this happening. Is it the J519? Please help

[@LAW-fv6ys]

Vag group use orange twisted pairs for can.

[@alrifainidal]

thank you so much great video

[@MechanicMindset]

Thanks for watching, glad you enjoyed it!

[@tomaszadach3775]

Thank you

[@KieranAKAbbq98]

Is this where the can-bus is? I thought it was in the trunk or passenger seat

[@ralphbowes1446]

I have a 2007 Ford F150 5.4l 4x4. I got 0 ohms between pins 6 and 14. I get 2.4v on both low and high sides.

[@MechanicMindset]

Shorted together?

checking shots between pin 4 und 14, ground und can low need to be 0v if is all ok if not ok than we have on multimeter some voltage or ohms so testing pin 4 and 14 or pin 4 and 6 can hi, need to be 0 on multimeter.

[@mekkibilal1372]

Hi I have seat leon 1p 2009 I measure resistance between can h can l I find 66 ohm But there is problem Why my scan tool can't access to all modules?? As I know I find power and ground in obd plug

[@eurowerx4267]

BMW 3 series!! PT can at EKPS module. Chasing a short to ground right now🥵

[@MechanicMindset]

👍

[@VirgiliuMatei]

Hey. I am facing a problem and cant solve it. Suddenly i’m getting abs/transmission /parking brake/steering fault code on my dash. The cluster freezes for a second and goes back to normal. The code comes randomly. Can you help me with an advice please. Thanks My car is a 2011 740li

[@freddiepacittidrummer.892]

Very cool thanks ....

[@EJAZenarosa]

Thank you

[@MechanicMindset]

You’re welcome!

[@stephanevaucelles6378]

thanks for video

[@MechanicMindset]

Thanks for watching!

[@Sean-zc3iv]

How do i test 2005 tahoe can bus system???? Obd2 only has 4 pin. So confused

[@francislucena5059]

Goid day Sir, i have aproblem with mitsubishi montero sports gen 2. It has acode " U1102 ASC CAN TIME OUT/ NOT EQUIPPED" . How can i solve this problem.. what is the cause ot this problem? Please Sir need your advice..

[@sidnarciso4872]

Can you check resistance on hot wires?

[@MechanicMindset]

Usually we disconnect the component or wire we test from the circuit.

[@sidnarciso4872]

Does can high have anything to do with voltage to crank sensor?

[@MechanicMindset]

Not directly

[@pablomarquez4431]

I got can low at 2.9 and hi is 3.3 not sure what's wrong

[@TemkaBr]

Спасибо, на работе как раз такой флюк, L~2.4 H~2.6 ,вот и думал это мультик среднеквадротическое показывает,ослика нет , а в мануалах по кану везде с осликом ,

[@MechanicMindset]

Sorry, I tried to translate this comment. Google Translate says you are talking about ‘donkeys’ 😂. I would love to help if you can comment in English 👍

[@Greg-lo1tl]

@@MechanicMindset I reckon Google wasn't working for him either. :-)

[@MechanicMindset]

@@Greg-lo1tl 😂😂😂

[@Greg-lo1tl]

@@MechanicMindset Coincidentally, I have a pretty interesting can-bus problem. Kicked my arse this weekend, still not fixed, although there's progress. It's a 2012 Chevy truck. I found a hard ground on OBD2 pin 6, with nothing communicating on that bus. Traced it to the ABS module on the frame rail. When I chase shorts I use my power probe and leave it on the shorted circuit. It provides a tone so that if I happen to move the wires near the short, I'll hear the noise change. In this case, the ABS connector had gotten cooked, not sure from what yet. But when I disconnected it, my power probe went silent. I think 'Aha, nailed it!" As it happens, the can--bus wires are right next to the big power and ground wires where the melting happened and they got contacted. But, even after disconnecting the ABS connector, still no communication and excessive resistance on can-bus. I'm at the point now where I think the ABS connector back-fed power through the can wire and damaged the BCM since it now keeps the brake lights on full time. That's as far I've gotten. It's a good one though.

[@MechanicMindset]

@@Greg-lo1tl Interesting! Got any further? I would get the scope on it to see exactly what’s happening 👍

[@standarulc]

with ignition on I measure can low oscillating between 1.9-2.2V and can high 2.8-3.0V is it normal reading or faulty?

[@MechanicMindset]

Hi, are you experiencing any faults? As we mentioned, the readings do vary between vehicles and networks. Plus the amount of network activity would have an effect on the readings too. If you have no faults, I would say these readings are ok; this is because they seem ‘balanced’ - high and low voltages share a similar difference compared to the 2.5V recessive voltage. If you are unsure, get the scope out - this is just a quick check, but gives undeniable results for certain faults. Hope that helps.

[@standarulc]

@@MechanicMindset well the truck went completely bonkers random action of wipers,turn signals,navigation... I also can't connect to any ecu except engine which is on different can circuit.I located the weird signal to transmission ecu but it contains terminating resistor so I can't just unplug it.Do you think I could buy 120ohm resistor and try to fake it to see how rest of the network behaves? Thanks for responding.

[@MechanicMindset]

@@standarulc Oh dear!! I would get the scope on it to see what is going on. If you can’t talk to modules and you are getting random events like you mention, somethings not right and it does sound network related. Have you checked the resistance? I also have another video explaining the CAN bus resistance check 👍

[@MechanicMindset]

Also, do you know if it is a high or low speed network? The voltages will be different to this video if it is low speed

[@standarulc]

@@MechanicMindset yes the resistance looks just fine at 60ohms.I will try to get oscilloscope.Thank you.

[@jamesbarratt593]

What if you have 38 kilo ohms

[@MechanicMindset]

Hi, could be that the CAN is still awake, try disconnecting Battery. Also are you definitely measuring a high speed network (this doesn't work on a low speed network).

[@triplextriplexxx8225]

but i could not find anywhere except china hantek probe leads ?

[@MechanicMindset]

Hantek are a Chinese brand. Some stores here in the UK stock the leads. I suppose it depends on what country you are buying from

[@triplextriplexxx8225]

@@MechanicMindset from ireland

[@triplextriplexxx8225]

@@MechanicMindset can you give me link of some shop that has leads in stock so i can order i can order to uk adress as well i have adress pall which is service that sends it to ireland

[@MechanicMindset]

triplex triplexxx Sorry, I have only seen them on Amazon. Try searching HT30A, I see quite a few results pop up. Alternatively, you could get the Pico automotive leads, although a bit more expensive

[@johnrieley1404]

Fluke has them but a set is $50 in US on Amazon "Fluke TP40 Automotive Back Probe Pin Set." Is use the Hantek, which are fairly good, but can't compare for I never had Fluke's.

[@funnylife2004]

Can you speak Cambodia ?😅

[@MechanicMindset]

Sorry, my Cambodian is not great 😂

[@MechanicMindset]

CAN Bus Diagnostics training now live from $10! www.mechanicmindset.com/diagnostic-coach

[@sirajlayas91]

Thank you

[@MechanicMindset]

You're welcome