Originally Posted by engifineer

Hello everyone, I just registered here today. Found the site while looking for this very mod. Figured I would search for it rather than re-inventing the wheel First, let me say thanks to those that figured it out. I will be doing this shortly to my 01 SR5.

I did notice someone was trying a momentary setup that would automatically reset when you turned the truck off. I tried reading all the pages (a lot of them!) and didnt see if they found exactly what they were looking for, so, as a car junkie and electronics guy, thought I could shed some light. I applogize if this is already posted and I missed it.

You can create a latching relay for this fairly easilly. It will work just like a motor starter in a sense.

First you need a relay with one set of NO contacts and one set of NC contacts. One set will be for the VSC disable and one for the latching portion.

Wire the NC contacts in the same way you would your switch to disable the system.

Now, for the relay control. Wire 12V ign power to one side of the normally open momentary pushbutton. Wire the other side of the pushbutton to the coil power on the relay. And of course, the other side of the relay coil to ground. So, when you press the button and release, it will momentarilly trigger the relay.

Next, to latch, wire the same IGN power to one side of the NO contacts. Wire the other side of that contact to the relay coil power. You are basically placing the NO contact in parallel with the pushbutton.

Now, when you bump the momentary switch, it opens the NC contact (disabling the VSC) and also closes the NO contact, creating a constant circuit to the coil, so when the pushbutton is released, the relay remains energized (this is sometimes called a memory latch as well). Since the NO contact is powered by IGN (switched) power, when you turn off the ignition, the relay will be de-energized, so the VSC system will be on again when you start the vehicle. That is, until you push the momentary button again to latch the relay.

Now, if I am misreading what someone is doing, please correct me. But from all I have read, the truck must be turned off and back on once the TRAC switch is closed in order to turn VSC back on. So someone wanted a way to have this happen automatically so they dont forget, then having to turn the truck off, close the switch, then back on.

If this is what they were needing, I would be happy to draw the schematic and look up the relay needed to do this. It is a pretty simple to build setup.

You can use this setup any time you need a latching relay and dont have one available.

Originally Posted by GSGALLANT

Good info, but you don't need that complex a setup in this case. All it takes to disable the system is a momentary interruption of ground. After that, you can try reconnecting it as many times as you want and it won't re-enable the systems until you shut the truck off and restart it.

So if you want it to be automatically reset every time you start the truck, wire in a momentary pushbutton with normally closed contacts (contacts open when you press the button). When the truck is running and you press the momentary button in, the systems will be disabled. When you release the button, the systems will still be disabled. Shutting the truck off and restarting it will re-enable the system. No relay required.

If you want a bit more control over when the system gets reset, install a regular on-off switch instead of the momentary switch. Turn the switch off to disable the systems, then turn the switch back on when you want to re-enable the systems (requires shutting off and starting the truck.)