Switched input question | AEM
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azfiveoh
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Joined: 01/07/2015 - 07:39
Switched input question

When looking at parameters some of the unused switched inputs are showing as 'on'. I am using a lighted 12VDC rocker switch to trigger a relay that supplies a ground signal to switch 1. I used a volt meter to verify that the there is no continuity to ground to the EMS pin when the rocker switch is in the off position and there is continuity to ground when the switch is in the on position. There are no wires connected to switched inputs 2 and 3. In the parameters section inputs 1, 2, and 3 are showing to be on and switching the rocker switch on and off has no effect.

The relay is wired such that pin 30 goes to chassis ground, pin 85 goes to chassis ground, pin 86 goes to switched 12v, and pin 87 goes to input 1 on the EMS. Pin 87a is unused.

Is there some setting in the software that needs to be adjusted or is there a problem with the EMS?

Thanks for your help.

azfiveoh
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Joined: 01/07/2015 - 07:39
As a quick update, I ran

As a quick update, I bypassed the wire coming from the output side of the relay and ran a wire directly to the EMS' switch 1 input pin.  The parameter window shows the input as "ON" regardless if the pin is grounded or not.  Interestingly, this only happens with inputs 1, 2, and 3.  The other inputs are working as they should be.

AEM_NS
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Joined: 06/06/2014 - 09:31
It doesn't really matter

It doesn't really matter whether the swtich input is shown as on or off in the software.  All that matters is that it changes states (on to off etc) when ground is applied.  If Switches 1-3 don't change states when connected to ground then they're either bad/damaged or you don't actually have a good ground connection.  

azfiveoh
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What are some common things

What are some common things what would cause an input, or series of inputs, to fail?  I checked the pins going to the computer and there is no continuity to ground or power.  When I activate the relay for switch 1 the pin goes to ground.  From my end the wiring is solid so I'd like to idenfity the potential root cause of the issue before I get the box repaired only to potentially damage it again.
 

AEM_NS
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I'm having deja vu because I

I'm having deja vu because I think you've asked this same question before but about a different input and my answer is the same as before: it's hard to say what could or would cause it to fail.  We haven't specifically tested the switch inputs to see what breaks them.  They're all supposed to be ground switch inputs (unless a specific app has been design to be otherwise) so it could be having them connected to something that isn't ground.  High current 12v comes to mind.  What are those switches connected to?  I'd assume they're only connected to something if they're being used for a specific purpose.  If not connected to anything, they obviously shouldn't be damaged.  The switches are all pulled up to 12v and connecting them ground brings them low and makes them change states.  The only logical thing it seems is that the circuit is damaged such that ground present at the physical pin on the outside of the box doesn't actually pull the input down to 0v.

azfiveoh
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Admittedly, I've had a number

Admittedly, I've had a number of issues trying to get the EMS to work in a non plug and play application but I don't recall having asked a question about an input before. To be clear, I wasn't asking what specifically could be wrong only what are some of the common causes of failure that you have seen so I can rule those out. Switches 2 and 3 are not connected to anything, yet they don't seem to respond when they are grounded. I'll do some more testing and see what I can figure out.