Aux Fan Control on Z32TT ECU on RB25?

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Torque
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Joined: Wed Jun 16, 2010 10:08 am

Aux Fan Control on Z32TT ECU on RB25?

Post by Torque » Mon Oct 01, 2018 2:49 am

I was wondering if I could use Pin 6 of the Z32 ECU to switch a relay based on coolant temperature.

Pin 19 is used for half blow fan speed, pin 6 for full blow.

However Pin 19 (On Z32) is cut during installation since it collided with the RB25 Power steering signal.

What's left is Pin6 as an output. (unless you bridge 6+19)

So where in NT can I set the parameters for Full Blow (triggered via Pin 6)?
Is it possible?

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Re: Aux Fan Control on Z32TT ECU on RB25?

Post by Matt » Mon Oct 01, 2018 4:02 pm

If TT ECU then two fan outputs, if NA then single fan output:
viewtopic.php?f=8&t=1861&p=12979

You can test fan speed with active tests
viewtopic.php?f=5&t=3497&p=26502

Actual operation of the flags Eric covered here
viewtopic.php?f=6&t=758
z32 fan controls.PNG
z32 fan controls.PNG (21.52 KiB) Viewed 1087 times
Pasting from that post:
Fan activate temp / Fan activate temp (AC) 90degC
0x7443 (stock value : 8C) is fan activation temperature offset with aircon off
0x7442 (stock value : 8C) is fan activation temperature offset with aircon on
Fan speed switch 1,2,3
3 byte table at 0x77ED (stock values : 00 00 00), defines the fan activation in relation to vhclspeed with aircon off
Fan speed switch 1,2,3 (AC)
3 byte table at 0x77F0 (stock values : D4 D4 00), defines the fan activation in relation to vhclspeed with aircon on
Operation:
from the 3 byte tables, the 1st byte is selected when vhclspeed is between 0 and 20kmh, the 2nd byte when speed is between 20 and 40km, the 3rd byte when speed exceeds 40kmh

the selected byte of these tables is then split into 4 sets of 2 bits:
the 1st set (00) is selected when temperature is below value of 7443 or 7442 minus 50 (< 90C)
the 2nd set (01) is selected when temperature equals/exceeds value of 7443 or 7442 minus 50 (>= 90C)
the 3rd set (01) is selected when temperature equals/exceeds value of 7443 or 7442 minus 45 (>= 95C)
the 4th set (11) is selected when temperature equals/exceeds value of 7443 or 7442 minus 40 (>= 100C)
meaning of the 2 bit sets:
11: fan on full blow , 01: fan on half blow (TT only), 00: fan off
the routine has 2 major overrides: if temperature equals/exceeds 105C (value of 7443 or 7442 minus 35) or if the ecu is in failsafe mode for whatever reason (eg. temp sensor disconnected) , then the fan is always turned on at full blow no matter what the vhclspeed is.

Matt
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Re: Aux Fan Control on Z32TT ECU on RB25?

Post by Matt » Mon Oct 01, 2018 4:03 pm

Just use the line where it goes to Pwr Steer on RB25 and route to the fan control line output if you want to use the 'full blow' line

Torque
Posts: 639
Joined: Wed Jun 16, 2010 10:08 am

Re: Aux Fan Control on Z32TT ECU on RB25?

Post by Torque » Mon Oct 01, 2018 10:20 pm

Thanks Matt.

I guess (as you say) just use line 19 (half blow)
Or just bridge 19+6 internally ...

Do you recall what value that SMD resistor has which was removed on Z32 ECU?
Is it important? Must be low ohm?
Z32Cooling.JPG
Z32Cooling.JPG (71.81 KiB) Viewed 1080 times

Matt
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Re: Aux Fan Control on Z32TT ECU on RB25?

Post by Matt » Tue Oct 02, 2018 1:07 pm

Not from memory. look at the RB25 / Z32 guide for images and that should let you know.

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