Can i use a ground switching output to switch an input?

[Subaru_EA82_4EAT_AWD]

I had a bit of a search but cant find anything on this one, perhaps because of the common keywords...

Can i use a switching ground output to switch an input?

I.E. Can I set my 'N20 1' output to switch to ground at low VSS, looped back to my 'tableswitch' input to change tables when not moving/not moving?

I could use a relay off 'N20 1' with the points connected to ground and the tableswitch input but perhaps I can do it without...

It would be good if 'VSS' was a setting condition for tableswitch.

[Marek]

Of course you can.

For example, I have manual relay controlled fans - the ground-side relay winding is controlled via a normal thermistor switch which would normally have been earthed to make the fan run.

I also have a MS controlled fans via "fan control". This outputs the fan control with VVT as the output pin. It can also activate the fan and has a diode between it and the relay winding.

To monitor whether the fan is on, the ground-side of the relay winding is wired as an input to "datalog in".

A diode links VVT and "datalog in" with the stripe pointed to VVT to insulaste the MS3 VVT pin from what the manual control is doing. The status of "dataog in" will now monitor and act on whether the fans came on manually or whether MS pulled VVT low.

kind regards
Marek

[Subaru_EA82_4EAT_AWD]

So, 'yes' I can do it without diodes, or 'yes' i can do it but i need diodes?

[Marek]

If you read the post, the input (datalog in) gets to see "earth" from more than one source. The only purpose of the diode is to provide a second grounding input that doesn't interact with the first.

When the fan is grounded manually, it is irrelevant what the MS grounding ouput is doing. Datalog in sees a grounded input and whether MS VVT pin is high or not is blocked by the diode.

When the MS VVT ouptut goes low, it grounds the fan relay itself and this is sensed by the datalog in.

When neither the fan is grounded manually nor by the MS output sinking the fan relay current, datalog in is at the fan relay voltage of 12v.

The diode's only job is to stop a potentially high VVT output from being shorted - MS might not like that very much.

kind regards
Marek

[nathaninwa]

If this is ms3, look into loop1 as an option, then in programmable outputs you can set that up internally. I was doing something similar but with reqfuel change, I didn't like the wasted output and input for an internal deal. Instead of adding rpm to the reqfuel switch, James came up with this rather cool Loop feature set

[Subaru_EA82_4EAT_AWD]

So, yeah, thankyou for the 'loop' feature - thats fantastic aye!

I set up my VSS input and calibrated the VSS,
I setup a programmable output on 'Loop1' with the condition VSS <3,
Then set my Tableswitch input as 'Loop1'

It works a treat - when I slow down to less than 3km/h my VE tables switch, so I have a completely seperate VE map for idle and low load.

For those that are interested, Subaru EA82 VSS pulse 2500 / km - this gets the reading very close to the OE speedo.