Rear defrost at temp control module latch or pulse?

Question

I have the EVO-ONE set to trigger aux 1 at -5C(It is set to pulse for .5sec without disarming the alarm) in a 2007 Nissan Maxima. It is wired to the rear defroster wire at the temp control module connector(connector that plugs into what houses temp controls/defrost button). It isn't triggering rear defrost but it's just barely cold enough too. So a few questions...

-Should I be latching instead for this car? I had a hard time finding the relay without somebody to press the defrost button so I went to the temp control module harness...didn't think it made a difference.

-Where is the EVO-ONE getting its temp reading to decide if it's cold enough to trigger aux 1? Will it not do it if the car is warmed up already? If it's pulling from inside the car(ambient temp sensor), then this makes sense(inside the car would have to be -5C then).

-What is "latch until shutdown" does it latch until you shut down the evo(as in take control of the car typically by pressing the brake) or until you shut off the car?
 

-Why would you latch for only 10-30secs? Is this what required to trigger the relay for some cars?(kind of like if you had to hold the trunk release for 10-30secs to trigger the trunk)

I'm just getting to testing this as it's just getting to 29F(-5C) here...

 

I do realize my defrost light won't intially be on. However, when I turn the ignition to "run", the defrost light should be on if it was triggered(which is not happening). I have tested this theory by sitting in the car, remote starting it, pressing defrost(no light comes on), turn ignition of car to "run" (light comes on at ignition turn) to know this.

Answer 1

The light on the switch will most likely not turn on since it's completely isolated from the circuit. Diagram below.

 

Rear defrost control is a (-)trigger at the BCM white 40-pin connector pin 9, WHITE wire. You will need to test if pulse or latch. This control rear defrost and mirror defrost. Also available at the unified meter, pin 38.

 

The EVO-ONE gets temperature reading from it's built in temperature sensor. So, as mentionned, if it's over -5 in the cabin, chances are, the AUX will not trigger.

 

"Latch until shutdown" is exactly what you think it is. It will stay latched until the RED led turns off (red led = unit on). Like you mentionned, until the unit shuts down, or when you press the brake.

 

This little baby right here: http://www.metraonline.com/part/TRIGGER will give you whatever kind of signal you want from whatever kind of signal it is fed. 

 

Comments

Thank you! I had just seen in a nissan forum that pin 9(white wire) on the 40pin BCM connector could be the wire I want to pulse! Thanks for helping confirm that(will still test the wire obviously).
 

Just got confused I guess as the Fortin instructions say to use the green/red wire at the defrost relay so since i had a hard time finding it, i just attached to the the green/red at the temp control module(happens to be same color wire). Forgot that I would need to setup a relay to use the connection I tapped.

 

I will rewire to the bcm harness since i don't care to put a relay in where I tapped into.

 

That dongle you linked is deffinately nifty...I like nifty.