Can bus to pulse width modulation convertor

Thread Starter

onebigburb

Joined Aug 23, 2023
7
First post so hopefully this is the correct place. I am looking for a convertor to convert a can bus component to pwm. I have attached a print with circuits circled in red. The only ones I have seemed to come across have 4 wire output on the pwm side? If there is not one out there already can one be made using Arduino or raspberry pi? Would like some king of simple scale table that I can set on a software side for controller so can bus 10% can equal 10% on pwm.

Side note I am electrician by trade, but start to get lost in the comms side of the world with the complexity.
 

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Thread Starter

onebigburb

Joined Aug 23, 2023
7
I saw that controller, seems it would work. Problem is is has 4 output wires. How would that work when the solenoid I am attempting to control only has 2 wires?
 

geekoftheweek

Joined Oct 6, 2013
1,256
Unfortunately when it comes to automotive applications there are no standard messages nor any published information about the messages other than error messages that are defined in various OBD specifications. In order to convert a CAN message to a PWM signal it's going to take a lot of reverse engineering to figure out which message contains the turbo data, how the data is actually arranged in the message, and what to do with the data.

You won't be able to connect a PWM signal to drive a OEM turbo actuator... there is a lot more to the actuator than that. Messages go both ways. The ECU will send out a message to let the actuator know where it's supposed to be. The actuator will when send messages to let the ECU know where the actuator is, if there are problems, turbine speed, and maybe more depending on what vehicle it is. If you plan on creating your own servo then that is a different story.

Best chance you have is to create something that connects between the CAN and the turbo and modifies the messages... good luck with that.
 

Thread Starter

onebigburb

Joined Aug 23, 2023
7
Just a guess, but is this a Power Stroke?
How did you guess dpf? lol

While I understand what you are saying about reverse engineering the message and it being a extremely difficult. I know that auto manufacture's tend to do some screwy stuff. Seeing that can bus has j-spec for its protocol's. I thought maybe it wouldn't be as bad to decode since there is standards towards how obd and j-specs are done. Maybe I am wrong?

Your servo comment peaked my interest after some thought. The controller currently in the truck use's a can bus, However it has a arm that moves the vanes in the turbo. I have not taken one apart yet to to try and see what is exactly going on inside. It maybe possible to use what ever is controlling the servo (I'm guessing) to control a solenoid instead using the existing controller.

Back ground on this may help. So I will attempt to write a short story and explanation on why I am looking to do what I am. Some of this is car talk and may make no sense to some people. The project is a 2008 ford f350 6.4l. The turbo setup from factory is ok but leaves a lot to be desired as you build the engine. Due to the fact this engine was only produced for 3 years the after market support it has is limited. The turbo(s) are a compound setup and as you build more boost you can start to see extreme exhaust back pressure ratios due to the a/r of the turbo(s). The housing of these turbos have some pipe work built into them. The pipe work gets in the way a lot and because of this you cant just switch to another more generic turbo option with out making some things fit. To my knowledge no other turbo that will fit in this location use's this actuator to control the vanes. If It was controlling vanes with PWM the turbo options open vastly. There is one after market company now making their own vane (vgt) controller now. The thing I don't like about it is having to use their software to program for the vanes table instead of using oem tables. I would like to use ford 6.0l turbo platform with vgt to cure all this. The only problem I have is how to get the solenoid in the 6.0 turbo to work on my can bus system. I left out some more minor details for the sake of not writing a whole book.
 

geekoftheweek

Joined Oct 6, 2013
1,256
How did you guess dpf? lol
The oil pressure switch on an eight cylinder diesel instead of a sending unit / sensor. One thing I could never understand is Ford's stupid oil pressure gauges that is actually a light disguised as a gauge. It was really a lucky guess, but seeing that in the diagram made me think Ford and I went with it.

I'll admit I don't know much about automotive CAN as I dealt more with heavy equipment which does have a standard, but everyone implements it differently... they follow the standard, but there is a lot of repeat information defined and they don't all use the same messages because of it. I have not had much luck myself finding the information to make sense of automotive CAN specs which may have lead me to say the wrong thing.

While I may be just guessing I would be willing to bet any change in boost is going to cause ECU faults. It's going to show a higher than expected intake pressure in the MAP sensor, the MAF will show a higher than expected reading, and I don't know how it will affect exhaust temps or if that will lead to errors. I know in the late 80's the MAP signal was PWM. MAF I believe was always a variable voltage.

The servo idea won't be hard to do with an external actuator. This project is something I would love to get in on, but for legal reasons I'll have to bow out.

Good luck
 

Thread Starter

onebigburb

Joined Aug 23, 2023
7
O boy, don't get me started on the dummy sensor stuff. Drives me bonkers. I have a hand full of sensors I wired in to another monitor so I csn see real numbers.

I must agree CAN is what has me put in this place. Anything else I would not even be asking. Its like my work. I am a plant electrician I deal with control circuits, instruments, analog, and discret every day. I am fine right until the PLC side. When it goes to cat5 I'm out lol.

I have full control of boost tables so this is no problem. I can trick the ecm into what ever set point is needed. I just need to have it control a diffrent componet and think the actuator is still doing the same thing.

I totally understand on the legal side of things. I dont think I will get to much farther until I open up the actuator and see exatly what is inside. I do appreciate your response though it got me thinking!! Sometimes that is all someone needs. I do it with apprentices all the time just idea bouncing can make or break a project.
 

geekoftheweek

Joined Oct 6, 2013
1,256
I must agree CAN is what has me put in this place. Anything else I would not even be asking. Its like my work. I am a plant electrician I deal with control circuits, instruments, analog, and discret every day. I am fine right until the PLC side. When it goes to cat5 I'm out lol.
I'm at a point where I would love to be able to go back in time 30 years and drag my sorry butt off the couch. I understand the basics of prox switches, switches, safety prox, photoeyes, VFDs, servos, relays, solenoid valves, and a few more things I probably forgot, but don't have enough experience or education to even get a chance. I learned a lot when I worked at a factory just because I wanted to know how things worked instead of just pressing buttons all day which lead me to many days of fighting to stay awake on machines that would chew people up and spit them out on a daily basis. I knew what things did, why they did what they did, and what to look for when things weren't right. I wasn't afraid to tear something apart and put it back together, but also knew when to ask for help.
 
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