Printer Friendly Forum Posts - ’02 S10 12V when running wire location

Hi,

I'm installing some foreign two-way alarm/starter combo in an '02 Chev S10 and the unit doesn't have tach sensing. It wants something that will give 12V when the vehicle is running. I can't seem to locate such a thing anywhere in the truck. The alternator doesn't have a status output by probing it and I can't even get a finger down to the oil pressure sender. Any help appreciated asap!

Greg

Are you using a voltage sense for determining if the truck is running?. If so just go to any 12v wire, when the vehicle is running the voltage is higher than if it's not. I do this with some deisel trucks...

It's not even a voltage sense wire. The install manual states:

Purple (+) this wire must be 12V when the vehicle is running and show ground when it is not. Use the vehicle's charge light or oil pressure sender wire.

I bluffed it and found that there doesn't have to be a ground when the vehicle isn't running, but 12V on the line with the vehicle stalling will not trigger a restart. If I simply attach the purple wire to the IGN output the vehicle starts fine and runs fine, but should it not start on the firest remote attempt it won't try again because the IGN wire is fooling it into thinking that it's running.

This is very frustrating.

Anybody?

Someone must have come across this problem before?

Ya got me stumped, the ground must give the RS the ok to give a restart. but 12v when running and ground when not.. what kind of rs is this? I looked through all my software for something to give you those parameters and I got nothing., I don't have a S-10 shop manual either. How many wires are at the back of the alternator? mabey you could go to the alt output, through a relay , and when the vehicle shuts down you can get the relay to rest at ground. that seems to me to be the problem...
Ill keep thinking...

Hymer

yeah man, that sucks?????????

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hey, everyone has got to start somewhere. but ill learn

It's a 2-way Hua Tai HT-800D that was purchased on ebay.
All google searches turn up is pages in chinese.

I found that it doesn't need the ground signal to start but it does need to see 12V when the vehicle is running. I know this because I can leave the wire disconnected and the truck will attempt to start. If I quickly give the wire 12V when the truck starts it keeps running. If I remove the 12V it attempts to restart.

The alternator has two wires, gray and red. Neither wire probes as positive or negative when the truck is running. Even if I could find something that gives a ground when running I could wire in a relay but I can't even find that.

As stated earlier, I tried tach and voltage sense with no luck. The manual specifically states 12V while running and I've proven that it does indeed need that.

*sigh*

alright, i am new at this so if this is just dumb dont talk too much crap about me.

so, here i go. from my gained knowledge of r/s systems you put a relay on the ign wires. that only let 12volts when you have activated the r/s. could you somehow confuse the system. and put that 12volt problem wire you have on one of the ign relays. it would make a big loop in itself, but the way i se it. when you r/s, the relay opens, and as it sends the 12volts to your cars electronics, it can also send 12volts to that relay you are talking about. just a thought. i hope i might of made some sense with all that

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hey, everyone has got to start somewhere. but ill learn

That's the way I have it connected right now. The only problem with it is that the r/s system leaves the IGN line at 12V even if the vehicle stalls or doesn't start on the first attempt because it doesn't know it stalled or didn't start. That's usually the job of the tach sensor or voltage sensor (increase from 12V to ~14 volts when running), which this system isn't capable of sensing either one of those.

well man, i dont know what to tell ya, im kinda new at this stuff

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hey, everyone has got to start somewhere. but ill learn

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 shot

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Driving 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 work

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Driving 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..

https://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...

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Driving a Bagged, Caddied 02 s10