Wiring advice please.

[cgtdream]

Hi all, im kinda at a loss at trying to get an electric water pump to activate through a throttle signal only. It sounds simple i know, but i cant think of any device that i can use that would only allow a 12v signal to the water pump ONLY when a throttle signal is present.

It would be great if anyone had any helpful ideas! Just FYI, the same system exist on the celica GT4, but it appears to be an ECU secret and i have no schematics that i can survey for information on this....

Also this water pump is for an WTA system, so please no comments on the silly idea of using this type of wiring setup on an electric water pump meant for the engine.

TL;DR
How do you switch a 12v source on and off using the 1-5v range off the throttle sensor automatically.

[BoredEE]

One method (which isn't going to be easy): Buffer the signal through a voltage follower op amp then into a comparator with a threshold set by some voltage regulator thats adjustable. Which then goes through some medium current switch MOSFET to turn on a mechanical relay.

I'm sure theres a product out there that'll do it better than this method.

You might want to search around for "analog to relay control"

There are RPM switches available that switch off the engine speed instead of the throttle position, just set the RPM switch slightly above idle engine speed.

MSD makes one. Typically used to replace the VCT function on RB20 nistuned ecus on RB25 engines.

If your throttle body has idle/WOT switches like a Q45 throttle body then it becomes trivial just wire a relay to be on when the throttle body is not at the idle position.

[Chaluska]

have you thought of tapping into the gas pedal bracket, and mounting a "brake light switch / Cruise control deactivate switch" touching the gas pedal linkage, and have the switch "on" with the gas pedal off, when you push the gas pedal down, it will open the switch, which can close the circuit.. that way it wont run with the gas off, but when you start accellerating, it will use water pump

[cgtdream]

have you thought of tapping into the gas pedal bracket, and mounting a "brake light switch / Cruise control deactivate switch" touching the gas pedal linkage, and have the switch "on" with the gas pedal off, when you push the gas pedal down, it will open the switch, which can close the circuit.. that way it wont run with the gas off, but when you start accellerating, it will use water pump

Good idea, but then wouldnt it have to be at WOT to activate? I was hoping to have it work the second any throttle was applied.

[cgtdream]

One method (which isn't going to be easy): Buffer the signal through a voltage follower op amp then into a comparator with a threshold set by some voltage regulator thats adjustable. Which then goes through some medium current switch MOSFET to turn on a mechanical relay.

I'm sure theres a product out there that'll do it better than this method.

You might want to search around for "analog to relay control"

There are RPM switches available that switch off the engine speed instead of the throttle position, just set the RPM switch slightly above idle engine speed.

MSD makes one. Typically used to replace the VCT function on RB20 nistuned ecus on RB25 engines.

If your throttle body has idle/WOT switches like a Q45 throttle body then it becomes trivial just wire a relay to be on when the throttle body is not at the idle position.

Im working with the blacktops TPS sensor, so it will work the same as the q45, right? Im looking into it right now.

EDIT: Think i found what you are talking about. Will work just perfectly for my setup. Thanks for the help, both of you!

[Jjwrangler]

If your accelerator system is not really but about to be like idle switches like a Q45 accelerator system then it becomes trivial just wire a relay to be on when the accelerator human is not at the nonproductive position.. . . . . .

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[suspectu1]

Good idea, but then wouldnt it have to be at WOT to activate? I was hoping to have it work the second any throttle was applied.

the switch proposed would work the way you want it if you use it to trigger a SPDT relay.
oh and you can find those switches in both normally-open and normally-closed.