H-200 Automotive CAN Bus Troubleshooting with Vince Fischelli

[Music] okay this is the fifth troubleshooting trainer and it's called troubleshooting can bus circuits when I began to think about providing some training and CANbus topics I I knew that hands-on was the way to go so the question was what to put on the circuit board to train in so what I did is I went around the internet and I looked at various places where people were documenting their difficulty troubleshooting can bus circuits and of course there was a number of topics but there were two that stood out to me when it was all said and done as somebody was documenting their agony of going through a vehicle with a can bus problem I pay particular attention to what was the final resolution that fixed the problem and two things stood out first of all people do not understand many technicians do not understand the can bus 60 own wiring network and as a result they bypassed our missed problems in the 60mm Network and and the second area that seemed to cause so much difficulty and yet fixed the problem when it was finally discovered was the nodes as they're called the PCM the BCM the TCM I just have three in my example here to illustrate the principles it doesn't require replicating more circuitboards more onboard computers but three is sufficient to address the problem that many technicians were overlooking and that is the voltage feed to the control units and the ground circuit so between the network problems and the voltage and ground problems of the nodes I could see the clear need to provide a circuit board trainer that would address those two single issues so that's what we have here with the can bus circuit board trainer HPC b200 and it's in module 200 now notice that the can bus board and the power board go together to create the can bus circuit now I want you to realize that there are no voltage or signal on the can bus network that was just too expensive to replicate so we do not have the ability to measure voltage and signals on the can Network but what I do have the ability to do is measure the 60 ohms so this is the workbook when you buy the can bus program h200 you'll get one of these circuit boards you'll get a workbook and an instructor guide with all the answers and a resistor bag with the appropriate parts to insert the different types of problems that you will have to deal with ok so now let's take our own meter and in this case as you'll read in the workbook we suggest that you measure the 60 ohm network using a digital ohm meter do not do it with an analog and you'll read about the reasons for that in the workbook but I'm going to take this digital ohm meter now this is as you've noticed all through these videos this is manually selectable it's not auto-ranging I find that teaching electrical classes with an auto-ranging meter you spend more time trying to understand the meter because that decimal point keeps jumping around from one reading to the next and so to avoid all that confusion we have decided to stick with manually selectable meters and that's what we've been using ever since notice that I've set to the resistance range and I've selected to K ohm resistance range another the reason for that is that yes when I measure between 6 and 14 on the DL C I'm going to see 60 ohms as you see here I'm measuring right there on the DL C pin 6 and 14 and I see 60 ohms now why do I want to select the two thousand ohm range well as you'll read about in the workbook if you place your probes into a circuit and there's an open connection in certain conditions you're going to read 240 ohms anytime you see 240 ohms as you will read in the workbook it means that between the two places you are testing there is an open wire so you've already found the problem you've already identified where the problem is you just have to go to that wire and fix the break and you'll be back to normal again in some cases and of course if I set my meter on 200 ohms I can't see 240 ohms so the meter would say open circuit and that would mislead me as to what's going on I need to see that 240 when it appears so if I'm on the 2k ohm range and I measure pin 6 and 14 I'm going to see 60 ohms I'm getting the job done now suppose one of the termination resistors is disconnected here or say it's broken in the vehicle when I go to pin 6 and 14 I see 120 ohms so that tells me one of the termination resistors has been disconnected or is broken and this is all explained in the workbook little by little we're going into 60 ohms in parallel to 120 ohms in parallel results in 60 ohms and all explain so you'll understand it and it also tells you why we have 60 ohms for the network and all those kind of things that you'd always want to know before you go to bed at night and so it's in the workbook I'm just showing you that I can measure is 6 and 14 and get 60 ohms now something can go wrong in the network and I will still see 60 ohms at 6 and 14 so you have to realize there are still things that could go wrong with this network and you still see 60 ohms so guess what you go on the bottom side and here are all the zero ohm resistors you open you pull out a zero ohm resistor and you create an open circuit in the network and then from the top of the board you take your own meter and you trace the circuit and we show you how to do that now it's so easy to do it on the circuit board because everything's right here you don't have to lay down get up under the dash and count pins on a connector you go right to the pin and take the measurement so that you can learn the technique without a lot of hassle in other words each node will be connected to the main CANbus network and so if you have the can plus terminal on the PCM that's a direct connection to pin 6 so you see 0 ohms that tells you you've got a direct connection then on can- on the PCM that connects directly to pin 14 and you see 0 ohms so you know the PCM is properly connected to the network now I'm probing here pins and 16 I'm sorry 6 and 14 on the DLC and I'm seeing my 60 ohms but what I'm important to say is don't do this on the DLC on the car because the pins in the DLC were not made for you to probe with the leads of your test leads pressing on those pins could deform them so that when you plug in your scan tool you don't get a good connection and you start having additional problems in it that you shouldn't have to deal with so what do you do then well you buy one of these little plugs that extends the DLC and you plug it into the car and then at the other end of the cable is a connector and you can probe your pins at that end and see your 60 ohm Network and do your troubleshooting just don't press on the pins in the DLC on the vehicle they'll be damaged too easily so there you see we can go through a series of resistance checks and verify any kind of an issue say for example a trouble code exists and the trouble cou trouble code says the TCM the the PCM cannot read or hear the TCM and the BCM says the same thing I can't see the TCM and there's a trouble code for that and it's listed in the book in the workbook well then you would go over to the TCM and you go to the can plus pin and see if it's connected to pin six and of course it is because we don't have a problem here and then we go to the can - pin and go to pin 14 on the connector and again we see a zero ohm reading indicating the TCM is connected to the network so that eliminates a wiring problem in the network as to the reason why they can't see the TCM and it's not contributing it's not talking it's not functioning it's gotta be a TCM problem internally now the wiring is not the problem but what if there is something else wrong with the issue of the TCM maybe it has a bad ground or maybe it has low voltage supply so I put my meter back to 20 volts and I ground it battery negative which is the negative post the black post and I touch the B+ pin which is marked TP 205 and I see there I have twelve point eight seven so I know the PCM is getting voltage and then I go to the B - pin on the TCM which is the ground pin and I see zero point zero two so I know the TCM has a good ground so now the TCM if it were a light bulb with B+ on one side and B - on the other the light bulb should write light right well the PCM should function if it has B plus and B - but if it's not giving you a signal out there's got to be something wrong like most likely inside the TCM itself so you see we're demonstrating the two most common problems that have caused the most trouble for technicians dealing with and bus issue first of all it was problems with the network wiring between the network and each individual control unit and the absence of or low voltage or absence of voltage or a bad ground connection for one of the nodes all of either those issues are often overlooked because they're basic simple troubleshooting that verifies the circuit can operate properly and you have to do that anyway before you can condemn one of the control units being defective and so that's just the series of problems that you have so in the workbook we go through 20 problems with the network now we'll break one of the wires between the control unit and the network or we'll break the network and a couple of problems we hook up the network backwards so somebody got in there and and did some wiring repair and didn't realize it but got the two wires going to the BCAM got them crossed how do you find that well you take your own meter and you do the test I was just showing you and you would identify that there is a problem with the canvas wiring to the BCM and then of course if you have low voltage or a ground problem with the voltmeter tests you would then be able to identify why that control unit is not functioning properly due to a voltage problem or a ground problem and so since those seem to be the two categories that resolve some of those crazy car problems out there that technicians struggle with for days only to find something simple like that we decided to produce this can bus troubleshooting trainer that addresses those two issues only and so the workbook itself has something like 70 80 pages 75 pages they're schematics and diagrams and step-by-step discussion of all of these two issues and how they relate to a real-world situation then you can practice your troubleshooting of each one to find out what's wrong with the can bus network do it here successfully and it will make your life a lot easier on an actual vehicle because you'll understand how all this works together to make that canvas function properly and of course up here on the Power Board we'll throw a few problems up here as well just to keep you honest to make sure that you're remembering there's a whole system here that has to be validated and confirm good before you condemn anything you make sure you know that everything else is good so that's it those are the five circuit board trainers that we offer and you'll see links there to get the information you can read about each of these circuit board trainers on our website and there's a link there you can click on the link in place an order on our secure shopping cart and that's it for now good luck with your troubleshooting you you

Channel: Vince Fischelli

Views: 20,235

Rating: 4.9065418 out of 5

Keywords: H-200 CAN Bus circuit, 60 ohms at DLC, Vince Fischelli, network ohmmeter DMM, 120 ohms at DLC, 240 ohms at DLC, digital ohmmeter, analog ohmmeter, CAN Bus network, measuring CAN Bus network, Nodes, open circuits, broken wires, measure Node B+, measure Node B-, ground circuit, DMM, voltage drops, shorts to ground, shorts to voltage, digital ohmmeters, analog ohmmeters, ground side problems, voltage side problems

Id: _Mb2mYUJG3s

Length: 18min 33sec (1113 seconds)

Published: Tue Sep 19 2017