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AUX/Fan no signal

Jo LeForce

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Got a G4 Extreme plug'n'play Evo 4-8 ECU, the wiring loom is of an Evo 7. I'm not getting any signal out of auxiliaries to operate the fan! I assigned the fan to 3 different auxiliaries to no avail. The fan works fine when fan wire is grounded which eliminates any fuse/fan motor issue. Using a multimeter I found that the ECU is not outputting a signal through the assigned AUX when fan conditions are met! 

Any suggestions ?

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The engine fan system does vary across the Evo 4 to 9 models.

Most Evo 4 to 6's will have the engine fan work by grounding pins 20, 32, and 34 through Aux-Ignition 4.

Some Evo 7 and 8's and all Evo 9's will control the engine fan by applying a PWM signal to pin 21 via Aux output 1. I believe 100% in the duty cycle table will give 0% fan and 0% in the table will give 100% fan. The relationship is inverse.


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  • 6 months later...

Out of interest, would this work with a straight on/off output or do you have to use a GP PWM output?

Any examples of setup? We tend to use aftermarket fans and go with a simple on-off relay, but have got a fairly stock car here at the moment that I'm setting up with stock fan controller.

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That bulk of stock controllers will be a simple set up of high low and maybe a medium speed controlled via simple on off type signals.

But there are some that use a PWM signal and in that case will need to use a GP PWM out put EVO being one example.



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