’02 S10 12V when running wire location

i got an idea.. tap into the tach with 2 relays.. wire one to put 12 volts to teh wire when it gets voltage from the tach adn the other to ground without voltage basically like this.. relay 1: 86 - tach wire 85 - ground 30 - +12v 37 - 12v when running relay 2 86 - tach wire 85 - ground 30 - ground 37A - 12v when running... this way... both relays will click over when 12 volts gets to them...   the only problem i see is you may have to diode isolate each relay to the 12v when running and i would suggest fusing them the first attempt.. give that a shotDriving a Bagged, Caddied 02 s10

I really doubt you want to put that much load on your tach wire, or flip those relays that quickly... Me

ok so then just hook up 1 relay to the tach wire and then the 2 relays off that... its just a suggestion that tech would workDriving a Bagged, Caddied 02 s10

It doesn't need to see ground, 0V is fine. So that takes it down to one relay.. But, would that actually work? Ot would the relay attempt to become a buzzer? Would the coil control module in the truck be able to handle the elctrical load of a relay on it without harming the tach output?

Depending on where else in your car tach goes, and how it gets interpreted (pulse counting or voltage averaging), putting even one relay off the tach wire could throw a check engine light. I've seen it happen from putting an alarm's tach wire on an injector. Also, the tach wire is sending out 1000s of pulses per minute-- so that relay is going to be flipping 1000s of times per minutes. Given that relays are rated in terms of tens to hundreds of thousands of flips for a lifetime, that means that this relay could be expected to give out in a week or two of driving... Assuming it can actually flip that fast, which will depend on the particular relay. Me

So as I originally thought, not an option. Thank you. Keep the ideas coming though.. This is very frustrating.

What signal does the RS need to reset itself? when that wire sees 0v it does actually it reset itself? This may be a bad idea, but have you poked around the tranny harness at all for this type of signal? sometimes there is a tourqe convertor lockup function that will give you 12v when running..

Greg-- I think your questions are right on-target, and would recommend you get authoritative answers from a mechanic (or someone who knows relays better than I!!) before proceeding down this path... I guess you could buy something like this and run it near a coil wire. Gack, what a kludge... And they make this thing which is getting closer to the mark... Probably pretty expensive though, and a lot of functionality you don't need. My solid state electronics isn't so good, but there must be some sort of module out there that measures voltage and provides a signal when the voltage is below (or above) some set point. That would be all you'd need (+ some low-current relays). Me, not very helpful today

The unit does reset at 0V. That's it's trigger to show that the truck isn't running so it attempts a restart. As for the trans probe.. It's an idea that I haven't explored. I'll have to talk to a GM mechanic by the sound of it. As for the links to the solid state devices also posted - Thanks, but if I tell the guy he needs to spend another $100+ US he won't be too happy. I've never seen a remote start that doesn't have tach or voltage differential sensing. Hopefully I never see one again! *Note to self - Hua Tai = Don't install.

heres a link on how to make a voltage meter.. it has an adjustable pot switch to set the voltage... instead of installing an LED just do the 2 relay setup off that...   i would suggest metering it out so u know when it switches... just another thought.. http://www.s10forum.com/forum/showthread.php?t=111646 i havetn looked at the design all that much but u should be able to alter it so that u can get it to do what u want...Driving a Bagged, Caddied 02 s10