WOT microswitch

[Hen]

Chris the transistor controls the relay. If you have current flow in the side (from TPS wire through zener and resistor) and out the bottom then the transistor allows current to flow in the top and out the bottom.

Also it just sprang to mind that if the MT is reading funny TPS signals then it may be because the TPS is sending funny signals. Maybe check the TPS signal wire with a multimeter as you move the throttle.

Hen

[boxh34d]

Microswitches are used alot in pneumatics. In the water industry, we use microswitches inside valve positioners to say whether valves are open or closed etc. Depending on the setup, I think they can be used in either a powered signal of 12V, ( on / off ), or a 4-20mA ( variable ) signal.
I know you have found another method of setup, but this might be an option if you have trouble. They are quite often just a small roller on a rocker arm. This could work perfect for throttle sensing.

Someone like SMC pneumatics, or a pneumatic valve company like Keystone ( owned by TYCO now i think ) would be a good place to start. I'm sure they could be available through an electronic / automation supplier too.
Only worth a couple of dollars.

[takai]

Maybe also refer to the switch which Jesse used for his kickdown switch. he mounted it off the throttle stop plate on his 2JZ.

[bansheebuzz]

your diagram is all wrong, i have rectified it. What is the microtech switching by the way, im bit confused as to why you put it in the diagram?

[chris davey]

I can't see much difference other than you used the 12v relay to switch the solenoid.

The microtech is using an output so that it will pull ground when certain conditions are met. I will set this to >3000rpm and 100% TPS so that the original signal will not be sent until this moment. This means that not only do I have to switch the main control switch and have 100% TPS but the power will not be sent to the solenoids until 3000rpm is achieved. I could also put in MAP level but as I am using it to bring on boost then I don't want to do this.

I think I will persevere with the microswitch and see if I can find somewhere suitable to mount it. As Hen said, if the MT is reading funny then the TPS could be sending funny and in that case it would be a lot of trial and error to get the readings correct.

Thanks for help everyone.

Also, the MT pulls ground and goes to that relay which sends 12v out. That is why it is in the diagram.

[takai]

Uh, you dont want to have the 5v relay being the continuity for the ground. More the continuity for power. The spikes when the second relay turns on will fry the 5v.

[lojik]

Just out interest, why not just use a microswitch on the throttle body?

[brett_celicacoupe]

edit: i should read people's posts more before i reply


in re to hen's circuit:

a low value resistor will alter the TPS voltage the ecu see's once the transistor is active.

you could also add a pot to that circuit to make the switch point variable

brett

[chris davey]

My auto is manualised anyway.

This stuff is starting to go over my head as I am not real good with circuits etc. so I am thinking maybe the normal switch is the way to go.

Hopefully this info. will come in handy for others.

[amichie]

hen,

you have the diode backwards. you want the current to flow from the TPS, through the tranny and to ground.


if you make this circuit, make the "resistor" value as high as possible while still letting the tranny work properly.

a low value resistor will alter the TPS voltage the ecu see's once the transistor is active.

you could also add a pot to that circuit to make the switch point variable

brett

Why not use a simple non inverting comparator. No current issues since Op amp is essentially infinite input impedance. Use an LM324 from Jaycar since it will go to the ground rail.

[brett_celicacoupe]

Why not use a simple non inverting comparator. No current issues since Op amp is essentially infinite inout impedance. Use an LM324 from Jaycar since it will go to the ground rail.

yeh thats what i originally designed for placentajuan

http://www.toymods.net/forums/showpo...8&postcount=18


looks more complicated then it is

[-==L=a=N=c=E==-]

hen,

you have the diode backwards. you want the current to flow from the TPS, through the tranny and to ground.


if you make this circuit, make the "resistor" value as high as possible while still letting the tranny work properly.

a low value resistor will alter the TPS voltage the ecu see's once the transistor is active.

you could also add a pot to that circuit to make the switch point variable

brett

it isn't a normal diode though, its a zener diode, designed to let current thru once voltage exceeds the rated value, in this case 4.7V's. The way he has it is correct.

[amichie]

The ECU and the TPS form a simple voltage divider circuit. If you suck current out through the Zener diode it will drop the voltage seen at the ECU.

[brett_celicacoupe]

yeh sorry i overlooked the zener bit.

edited

[Hen]

amichie - Yes a comparator would be a better solution, with essentially no current use or change to the TPS signal. However I'd expect the diagram above will also work, it depends a bit on the ECU internals that read the TPS signal, and the size of the resistor used.