CanBus Checks

[Blowndakrt]

I guess this is kind of automotive electronics.

For the switches that are CanBus controlled, does it constantly monitor the switches for signals?

I have been debating switching around some factory switches to run other things, but not sure if the CanBus will freak out if it sees no signal coming from a factory switch.

I would assume that it does constant monitoring to make sure all the switches are in place, but does it need to see a return signal even if the switch is idle.

Could I possibly diode isolate the output of that switch once I switch it over to run other functions? Kinda like a toggle switch to activate those switches to run other things, and the diode stopping the normal signal to the CanBus, then when its switched back, the normal function of the switch remains?

Any Input would be great.

Thanks

Shawn

[JonW]

Switches don't sit directly on the CAN bus. They are wired into things like the driver door module (DDM), passenger door module (PDM), steering control module (SCM), Cluster/EVIC, HVAC, etc.

It would help if you were a little more specific in what you are looking to do.

[Blowndakrt]

Well, I am not exactly sure what I would all want to run off of the switches just yet. It would depend on if its possible.

So for instance, lets say I wanted to be able to control a linear actuator through the driver's power window controls. I could use the up and down function of the window control to feed the actuator controller to move it up or down.

I would have a separate control that would "switch" so to speak the output of the window switch to run the actuators, then switch it back for normal power window operation.

I would assume I would have to come off the door control module to get a better signal. I would assume the power window switch just sends a low voltage data singal to the module.

Shawn

[JonW]

It's doable. Some switches are monitored. They may have a low resistance across the switch when open (10 Ohms for example) and then a high resistance when closed (100 Ohms or greater). Alternatively, they may have no resistance when open and a specified resistance when closed. You will need to check each switch as to how it operates. The factory service manual would come in handy for this as many of the tests to determine if a switch is faulty will list its resistance value for test purposes.

There's also a high-tech way to do this utilizing the CAN bus. Many of the switches in the vehicle transmit CAN data when they are activated. For example, my car has the ability to shift up & down by tapping the cruise stalk up/down (when the cruise is in the off position). I can also press and hold the cruise cancel for 3 seconds to activate/deactivate my cooling fan override. I can also tap the steering wheel > button to answer an incoming call (or press and hold 2 seconds to activate Uconnect to make a call).

[Blowndakrt]

Is that something that would need to be programmed into the CanBus? Also, those are all factory functions, so I am going to assume you would just need to send the Canbus singal to the proper factory module.

Also, would I need to find some sort of CanBus module that would be able to have postive or negative pulses of 12 volts?

If I go with the toggle switch idea to switch the outputs to run them to another source, would it cause issues with the CanBus not getting a signal from the swtiches and throw a code or cause other issues?

Also, I would like some more info as in how you got those alternate functions from your factory buttons. There are a couple I would like to have as well.

Thanks

Shawn

[007SRT8]

I can also tap the steering wheel > button to answer an incoming call (or press and hold 2 seconds to activate Uconnect to make a call).

Jon is this stock functionality or did you mod it? My only gripe with my Charger so far is that I have to reach up to the mirror to initiate uConnect...

[JonW]

Jon is this stock functionality or did you mod it? My only gripe with my Charger so far is that I have to reach up to the mirror to initiate uConnect...

Not stock. It is a custom microprocessor module on the CAN bus.

[007SRT8]

Can you elaborate a bit Jon? Thanks...

[JonW]

I've made a few of my own custom CAN bus based modules for certain functions. It's not a simple task of wiring a few things up. It involves IC circuit design and extensive software coding. At this point in time, there is nothing available commercially for you to accomplish what you want.

[007SRT8]

Thanks Jon.