Need help with how a circuit functions

Thread Starter

gte

Joined Sep 18, 2009
360
Can someone explain to me how this works? I'm trying to bench test the DC motor that operates this valve and I'm struggling how a DC 12v system would generate a negative PWM signal for (EXM-). I put a scope on the controller of the motor, but didn't see any frequency.

Looking at the below, I inferred that the motor received a PWM frequency to open and close and a source voltage to an angular sensor to determine being open or closed, but apparently that's incorrect, so if someone could comment where my understanding is wrong, I'd appreciate that. Also, what do the speaker looking symbols represent?
 

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LowQCab

Joined Nov 6, 2012
4,290
The PWM-Signals look like they may be following something like a CAN-Buss-Format,
where the "negative"-Pulse normally stays "positive", but the Pulses go negative,
which would be the exact-inverse of the "positive"-Pulse.

I don't know if this is correct or not,
but this scheme is very good at working in an Electrically-Noisy-Environment.

This looks like it might be an Electronic-Waste-Gate-Controller on a Turbo-Charged-Engine.

The "Speaker-Shapes" are just a funky way of showing that there are 2-Wires going to the same places.
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Thread Starter

gte

Joined Sep 18, 2009
360
I put my meter on the Exm+ and Exm- and both showed 12v. Strangely my scope shows 0.4v with no wave form on both. Possibly the scope isn't functioning, I can verify that later on. Possibly there are no pulses unless the vehicle is running and certain conditions are met?

Does this correlate with what you are speculating? If I understand what you have said, the Exm+ has a pull down resistor and its circuit goes high when it's outputting a frequency and the Exm- has a pull up resistor where its circuit goes low when it has a frequency?

Have I understood what you wrote and how could I best validate your theory?


The PWM-Signals look like they may be following something like a CAN-Buss-Format,
where the "negative"-Pulse normally stays "positive", but the Pulses go negative,
which would be the exact-inverse of the "positive"-Pulse.

I don't know if this is correct or not,
but this scheme is very good at working in an Electrically-Noisy-Environment.

This looks like it might be an Electronic-Waste-Gate-Controller on a Turbo-Charged-Engine.

The "Speaker-Shapes" are just a funky way of showing that there are 2-Wires going to the same places.
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LowQCab

Joined Nov 6, 2012
4,290
Read the Troubleshooting section of the Factory-Manual.

You still haven't bothered to mention a Manufacturer, a Part-Number, or even it's general-intended-purpose.

Unless You can provide some pertinent information, it's unlikely that anyone will be able to help You.

What do You intend to use it for ?
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Thread Starter

gte

Joined Sep 18, 2009
360
The images are from the diagnostic manual. I'll assume I understood your first reply correctly.

I'm not sure why my reply would prompt an "RTFM" however I'll take your advice from your second reply and post elsewhere.


Read the Troubleshooting section of the Factory-Manual.

You still haven't bothered to mention a Manufacturer, a Part-Number, or even it's general-intended-purpose.

Unless You can provide some pertinent information, it's unlikely that anyone will be able to help You.

What do You intend to use it for ?
.
.
.
 
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