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Problem with AUX GP output


Ryan Simmons

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Hi

I have a set of fans that i require to run constantly whilst the engine is running but only switch on whena couple of conditions are met. basically i ask for 'more than'  1500 rpm and 'more than' 30' ECT.  I wired the fan relay trigger into AUX4 amd configured as a GP output and set up the required conditions without issue.
Now, heres the problem. The fans remain off when less than 1500rpm, juat as they should and come on when the revs go over, but when i turn the engine off, the AUX defaults to 'on' causing the fans to switch on! so basically, when the ignition is turned off, the fans turn back on!!  How do i stop this?

Also, the voltage drop from the fans is quie a lot causing the idle revs to bog down quite bad, can i add an Idle up table thats assigned to the AUX4 output to allow me raise the RPM slightly at the moment the fans come on?

Thanks for the help!

Ryan.

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Previously Ryan Simmons wrote:

Hi

I have a set of fans that i require to run constantly whilst the engine is running but only switch on whena couple of conditions are met. basically i ask for 'more than'  1500 rpm and 'more than' 30' ECT.  I wired the fan relay trigger into AUX4 amd configured as a GP output and set up the required conditions without issue.

Now, heres the problem. The fans remain off when less than 1500rpm, juat as they should and come on when the revs go over, but when i turn the engine off, the AUX defaults to 'on' causing the fans to switch on! so basically, when the ignition is turned off, the fans turn back on!!  How do i stop this?

Also, the voltage drop from the fans is quie a lot causing the idle revs to bog down quite bad, can i add an Idle up table thats assigned to the AUX4 output to allow me raise the RPM slightly at the moment the fans come on?

Thanks for the help!

Ryan.

 

Wire the +ve trigger of the relay to a switched ign source, not a permanent one. Then when you key off, it doesnt matter what the ecu is doing, the relay cannot be energised.
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If I have got this correct currently there are two issues one the funs run when key is off. Second is the idle drops when fans come on.

The Fans continuing to run when key is off is solved as Stevie pointed out by changing the relays to not have a supply when key is off.

For the idle control this is not so easy to fix. Mainly as the fans are not being switched in there usual way.

You would normally compensate with a Fan step % increase in the idle control menu.

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If you have enough Aux outputs, you could stage the fans coming on so there would be less of a hit on the electrical system.

 

And when cranking, the PAS pump should not be an issue. Unless you steer a lot during engine startup.

 

And if you basically run the fans most of the time. You could look into using a changeover relay.

Effectively same as a normal relay except there are two terminals. One is closed circuit when energised, and the other closed circuit when not energised.

So in order to turn your fans on, you would turn "off" the relay. To turn the fans off, you would energise it.

Using this along with wiring an ign supplied 12v for power to energise the coil should resolve your problems. But you would need to flip/invert the Aux out settings for off/on

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Cant edit my post.....

The above may allow the fans to run when everything is turned off unless you also relayed the power supply for the fans in a conventional manner too.

 

But with so many fans already, an extra relay or two will hardly hurt. Even if the inverted one was only for triggering the others for example

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