Analogue Temp question

[Noslin]

Hello,

have a dumb question but Im a bit confused with the nomenclature of Analogue Temperature. AT1 & 2 are Air Temp and Engine Temp switch's. but, looking at adjust>digital input>switch's.. these are switch's so why are they called AT (for analogue temperature) and not AS for analogue switch or something to that sort?


ty

[AlanB]

Hello Ty

Although AT inputs can be used with switch inputs, in the M84 AT1 and AT2 are meant to be used with variable resistance temperature sensors, so you should make sure to connect this type of sensor to those inputs.

[Noslin]

thank you Alan for your reply. im having trouble wrapping my head around activating a digital input via a switch (AT). what im having trouble with is the Lo/HI level input. Adjust>Digital inputs>switch>setup.. hi/lo level.

i did some searching and found this explanation.

Just to clarify.

All Digital inputs on the ECU have a 5v pull-up internally. So, with nothing connected to a digital input you can use a multi-meter to see there is 5v (4.98v is close enough) on all the digital input pins, this is normal. You will also see the same 5v pull-up voltage on the Analogue Temperature inputs.

The digital inputs work by using a simple switch to connect the Dig to 0v. The input logic needs the signal to switch from above 3v to below 2v so 5v (with the pull up) switching to 0v obviously meets this logic and the Input goes active.

for lo activation, is it as simple as connecting to ground? so whether it be to activate dual-rpm, logging, anti-lag etc. can you just hook ground to the pin. eg; switch 3 (AT3).. connect to chassis ground via a mechanical switch on dash or whatever mechanism your using to activate it?

or, do you need to install a pullup resistor between whatever mechanical switching device you use and the ecu? and, in the quote it says "0v"... is this chassis ground or something on the ecu? (i see 0v pins on ecu wiring diag)

for the Hi Level, if you choose this activation i take it would be to a 5v source (can be from ecu?). or would it be from 12v source with inline resistor for safety reasons of backfeed?

thank you
dean

[AlanB]

Hello Dean

You don't need an external pull-up resistor with a digital or AT input.

When you connect your switch, one side goes to the digital/AT input and the other goes to ground.

Hope this helps.