Wiring diagram for center console button panel: anyone have it?

[airline tech]

Being that there is (1) thing missing from all diagrams, and that is input (Temp -Selected)

I think I have how the system works as this will account for your control test failing. at the Temp/Humidity sensor


The 5-Volt reference, will always be present and not change (5-Volts)
The signal return side- will be the differential varied voltage from all factors (Controlling) (Temp Sensors, Humidity/Temp Sensor, and the unseen (Temp Selection, Sunload Sensor, Ambient Temp Sensor) accounts and controls all door positions.
All of the unseen inputs are dealt with internally of the FCIM, and then tied into the actual external temp sensors that are viewable on the wiring diagrams.

Signal Return = (Voltage difference of the 5-Volt Voltage) and it is the (actual temp control / door control)
Thus, it is varying the ground return of the 5-Volt Reference by the Thermistor's and Capacitance Sensor and (Internal Inputs) from FCIM
The internal inputs in the FCIM also ties into the 5-Minute timer theory as the FCIM would have to be the (Control) for that timer.
The Timer control is not documented anywhere I can find, but we know some kind of timer is there or as you said, with high humidity readings in the truck, the Inlet Door should have stayed open and not timed out and commanded back to close by the FCIM

The key factor to look at would be the difference between Max AC and AC and all other selectable settings this would show the controlling (timer) as by documentation the Max AC setting keeps the Recert active, and the door closed. (So, in theory this would disable that 5-Minute timer)

But we can't see that specific, documentation, diagram on the internal control for that function.

Is this how you see it?

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[jblc]

Thanks. Yes, I've understood what you wrote as well. FCIM is the control module for this operation.

As i think i mentioned in some other posts though, sunload wasn't a contributing factor, because i did tests at night. Also, outside temp wasn't an issue because i did the tests at various temperatures.

Also a few clarifications:
1) "The 5-Volt reference, will always be present and not change" As far as i can tell there's no 5 volt reference. That's just the voltage input to the sensor.

2) The temp and humidity aren't a differential measurement. They're a straight analog output (~ratiometric, and not totally linear).
But since i did tests by sweeping through many different settings simulating different outside and inside temps, and humidities that were less than the outside humidity, these aren't the only inputs even at night with no sun load.

3) More precisely, i suspect this temp/humidity feature is actually not doing what they say. I'm beginning to suspect it's buggy and/or is mostly marketing -- and in fact in most cases there's just a timer no matter what the sensors detect. In some rarer cases perhaps they are monitoring those, but overall i think they're ignored.

 

[airline tech]

Correct - in automotive terminology
VREF = 5 Volts (control circuits)
And the sun load sensor will not produce a voltage output until it senses sunlight - the sensor serves (2) functions both hvac and auto headlight control - so zero output unless light is hitting it - the higher the light intensity the higher the voltage

 

[airline tech]

I have a question:
When you did your Wire Harness Mod where did you tap in.

I see it like this:

I think the (Temp Selection) buttons (Cold/Hot) are direct inputs to the motor drives for the actuators (+) (-) , example you want drivers side heat (Motor moves (CW)

So if we apply that same operation at the Air Inlet Door, then you have (2) controlling things that will move the door from the Humidity/Temp Sensor

In Auto-Mode, the only thing controlling it is the (Combined-Humidity/Temp) reading on pin-5, now that this ties into all the other doors and sensors, this is for automatic control and manual control of the whole system.

For Temp - Voltage Input = Pin 3 , and it ties into the return/ ground of the humidity return ground)
it is taking a combind return voltage and using that as input information to all other sensors in the system - For Auto/Manual) controll

Now, lets look at the Humidity side of the sensor only:

We have a 5-Volt sognal on Pin 3,
Then Pin 4 - is an actual Humidity output signal to the FCIM, why would it need to know that.

This is the side that controls the Air Inlet door itself, the Recirculation button, this is the by-pass that ties into that 5-Minute timer within the FCIM
This output signal tells the FCIM what the Humidity reading is, and Opens and Closes the door independently - based only on Humidity, however the FCIM only allows it to close for 5-Minutes

So, Pin 4 is the KEY output to play with (I believe) as this would be the main control full open and close control and overrides the outputs from pin 5

 

[jblc]

"the only thing controlling it is the (Combined-Humidity/Temp) reading on pin-5"
Pin 5 is Gnd. Also temp / humid aren't combined: there are two pins. One pin has temp, the other humidity.

"So, Pin 4 is the KEY output to play with (I believe) as this would be the main control full open and close control and overrides the outputs from pin 5"
Pin 5 is Gnd; not an output. And yes to Pin 4 See my post here for the pin inputs I used:
Pin 2 temp (resistance), pin 4 humidity (voltage).

 

[Trigganometry]

After watching that video the little copper disk he cleaned is a crude rheostat. It's a easy way to correlate resistance produced at both extremes of motor movement of the door. That how the FCIM knows where home is. It sees current rise at extreme stops and then records resistance reported. That way it's not always doing it. Well that is until it gets dirty. With the depth you have both gleaned in deciphering what's going on it really seems this is better attacked by hex control. Keep in mind that depending on the options packages the FCIM is probably going to be different.

 

[airline tech]

Very TRUE-I would love to find at the very least - what hex line or lines control the specific control for the inlet door or humidity
Honesty for me personally it does not bother me - this is strictly a quest for knowledge on the system and find a way to override a function that a owner should have the ability to fully control .
I have yet to actually break out the fluke meter for it and test myself

 

[airline tech]

pin 2: temp sens resistance input (It's connected to pin 5/Gnd)
- Higher resistance = lower temp
- Lower resistance = higher temp

Ok I now understand Pin 2 - It starts out as a 5-volt signal but the resistance from the Thermistor, varying by the temp, uses up voltage.
So, this voltage that is on Pin 2 is factored into the FCIM and read as a Temp Input.
5-Volts (Minus) Resistance Voltage = Temp Input to the FCIM

So, Pin 4 - Humidity and Pin 2-Temp are direct inputs to the FCIM.
They share the Ground (Return Signal), with the rest of the circuit.
The Humidity side of the sensor shares the 5-Volt Ref Voltage Circuit (power). with the rest of the actuators on the circuit
The Temp side (Thermistor) has to have its own (5-Volt) Power but can share the Ground.
Thermistor cannot share the Potentiometer (Power) circuit (5-Volt Ref)

 

[jblc]

Yep, exactly, you got it now

"the resistance from the Thermistor, varying by the temp, uses up voltage"
One small correction addition: the thermistor is just part of a resistor divider. So it doesn't use up voltage, rather it creates a voltage based on its resistance.

 

[Trigganometry]

Yep, exactly, you got it now

"the resistance from the Thermistor, varying by the temp, uses up voltage"
One small correction addition: the thermistor is just part of a resistor divider. So it doesn't use up voltage, rather it creates a voltage based on its resistance.

Almost, a thermistor is a resistor that changes value with the temperature. Thermistors increase or decrease resistance with changing temperatures.

 

[jblc]

Almost, a thermistor is a resistor that changes value with the temperature. Thermistors increase or decrease resistance with changing temperatures.

Yep, agreed. Hence saying that it's part of a resistor divider, and that Higher resistance = lower temp, and Lower resistance = higher temp (causing the voltage change in the dividor)

 

[airline tech]

Yep, agreed. Hence saying that it's part of a resistor divider, and that Higher resistance = lower temp, and Lower resistance = higher temp.

Just curious what your background level is?
Myself I have not had any board level experience- it’s just basic wire troubleshooting from time to time
With avionics - you have guys that love it and excel at it and then you have some that no nothing about wiring - I’m comfortable digging into it - basic check for power and ground - as that is normally all that is needed-for a mechanic- but inner workings of a box - board is left to vendor repairs - if box is not putting out power - replace it and send to vendor for repair- this for me as a mechanic is one of my weaknesses-I always get by with basic but throw inner workings of a box and I sometimes stumble
So just wanted to say thanks

 

[jblc]

it’s just basic wire troubleshooting from time to time

Ha, hard to totally believe Your insights and experiences are super valuable, and I've certainly appreciated the help many times!

So just wanted to say thanks

Sure thing; but I'll just reflect that right back...

Just curious what your background level is?

Not sure what to say about level Perhaps on the "knowledgeable" side? Either way, when a board like FCIM is in this state (locked up in epoxy, hidden traces / unknown firmware), i can't (as seen) work through that...
Hoping Forscan control will appear at some point, as you'd proposed before including looking at other vehicles...which i've looked through, with no luck yet.

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