Positive connection that only gets power when engine RUNS??

[RDKamikaze]

Howdy! I'm trying to figure out where I could connect something I need;s positive connection to my car. I need the power to be supplied for this ONLY when the car is turned on and the engine is running. Please help me find a spot to connect it. I was thinking the alternator's positive connection that leads to the battery, but where could I find that wire?

Any input and help would be greatly appreciated, thanks!

[BadAngel]

You need it when the car is on, or while the engine is running and the car is on? If so, then i can see where your confused...
If you just need power while the car is turned on (like the radio, or gauges) then theres a bunch of really easy places xD.... The power to the radio for example, or probably even easier is the cigarette lighter (aux power) in the compartment under the radio.... (personally i think thats the easiest) because if you pull out the compartment then you have access to the wires right there...

If you need the engine running, then your alternator idea is a good bet, just look on the alternator, theres got to be a wire coming off of it and going to the battery. If that doesn't work than try to trace the hot from the battery on my 2004 theres two wires coming off the hot of the battery so one of them must be the alternator, i would assume yours is the same.

[Gadgetjq]

Howdy! I need the power to be supplied for this ONLY when the car is turned on and the engine is running.

I think you're going to end up probing around with a volt meter to find what you need. It's very possible you'd be able to tap into a fuel injection relay. If so you'd want to use a new relay, toggled by the FI power (so your new accessory isn't drawing power directly from another circuit).

If the voltage regulator is built into the alternator on our cars then you 'could' tap into the "Batt" terminal on the alternator. If the regulator is separate then you'd need the "Batt" terminal on the regulator. Whicheve, you'd use that power to close a relay, not to directly power whatever you're hooking up.

Another alternative would be to simply install a manual switch on your dashboard (or inside your glove box or center console). Connect the switch to your 'accessory' fuse or accessory socket wiring and you're good to go. A small LED on the dash could be used to tell you whether the switch is on or off.

Cheers

[Gadgetjq]

RD,

I may have found your solution. It's that 'hidden circuit' that we forget about that keeps the DRL's from coming on when the handbrake is engaged.

Based on the service manual text (below) all you have to do is tap into Terminal (D)5 of the body ECU and use that signal to close a relay. You'll need a voltmeter to determine the signal voltage (if it's 12 volts this will be 'super' simple). Do 'not' try to power your new accessory from that signal. Here's the service manual text:

Daytime Running Light Operation
When the engine is started, a signal from the generator is input into TERMINAL (D) 5 of the body ECU. At this time, if the
parking brake pedal is depressed (Parking brake SW ON), the body ECU is not activated, and the daytime running light
system does not operate.
When the parking brake pedal or parking lever is released (Parking brake SW OFF), a signal is input into TERMINAL 19 of
the body ECU. This activates the body ECU and the headlight turns on.

Cheers

[[SMAN]]

RD,

I may have found your solution. It's that 'hidden circuit' that we forget about that keeps the DRL's from coming on when the handbrake is engaged.

Based on the service manual text (below) all you have to do is tap into Terminal (D)5 of the body ECU and use that signal to close a relay. You'll need a voltmeter to determine the signal voltage (if it's 12 volts this will be 'super' simple). Do 'not' try to power your new accessory from that signal. Here's the service manual text:

Daytime Running Light Operation
When the engine is started, a signal from the generator is input into TERMINAL (D) 5 of the body ECU. At this time, if the
parking brake pedal is depressed (Parking brake SW ON), the body ECU is not activated, and the daytime running light
system does not operate.
When the parking brake pedal or parking lever is released (Parking brake SW OFF), a signal is input into TERMINAL 19 of
the body ECU. This activates the body ECU and the headlight turns on.

Cheers

Yeah i just wanted to add that this wire is yellow with a green stripe. It runs from the instrument panel brace on the pasenger side. Pages 36 and 37 of the electrical part of the FSM will show you a diagram. If you have a coupe, it's pin 104, if you have a convert, its pin 94. Now the body ECU is located on the driver side (shown on pages 20 and 31) It is clear which is pin 5 on page 31. Those are your two best locations to tap wires from. I hope this helps.

[Down2TheC]

I think the relay theory by gagdet is your only bet. The alternator output that connects to the battery, it will be at 12V all the time even when the car is parked with no key. If you were to hook something to that line it would be the same as feeding directly from the battery.

Now it might be easier to find something that's a suitable ground when the engine is running. So you can connect it to an accessory fuse and the ground will control it's on/off.

[RDKamikaze]

Now it might be easier to find something that's a suitable ground when the engine is running. So you can connect it to an accessory fuse and the ground will control it's on/off.

What ground wires are only on when the car is running? I don't think I've ever heard of the ground on a car controlling the circuit, it's always been if the positive is connected (or on, or w/e) or not. That sounds like a lot easier of an idea.

The thing I need to connect is going to draw aboud 3A of power while the engine is on, just in case that changes anything with anyone. I've heard from sources that the windshield wiper positive or the ignition "ON" only get power when the car's running or on, but I tested that theory by turning on my car (but not running) and turning on the wipers. They moved. Why does wiring have to sometimes not make sense to me! lol

[[SMAN]]

Now it might be easier to find something that's a suitable ground when the engine is running. So you can connect it to an accessory fuse and the ground will control it's on/off.

What ground wires are only on when the car is running? I don't think I've ever heard of the ground on a car controlling the circuit, it's always been if the positive is connected (or on, or w/e) or not. That sounds like a lot easier of an idea.

The thing I need to connect is going to draw aboud 3A of power while the engine is on, just in case that changes anything with anyone. I've heard from sources that the windshield wiper positive or the ignition "ON" only get power when the car's running or on, but I tested that theory by turning on my car (but not running) and turning on the wipers. They moved. Why does wiring have to sometimes not make sense to me! lol

What you want to do is use a relay in this situation. You tap the trigger wires to that yellow wire with the green strip i was talking about and the other edge to ground. You then tap the switched wire to some sort of power (might be easiest to tap the cig lighter wire) and the other end to your device. A simple bosch relay will work for this (it's what we use all the time)

[RDKamikaze]

Thanks for the help so far! A guy on another forum said his setup is like this:

"I run the power directly from the battery through a relay.

Battery (+) -----> 25-30A Fuse -------> Relay --------> (+) cell (-) -------> Chassis ground


The relay is controlled by a low power source that is switched off by the ignition and a dash switch. Maybe use a source like oil pressure sender that is only live when engine is running, it doesn't have to be a high current source since we're using the relay to control that. This will draw a lot less than 1 amp, like maybe 25 mA. I use ignition (not accessory!) which works well enough for me since i don't sit in the vehicle with the ignition on for hours, (which would run down the battery and generate explosive gas)."

The "cell" is the thing that we are trying to run. It's an HHO gas generator. So the kind of relay in this situation would just be the bosch one (40A 12VDC)? Are there any sources that are in the engine bay where the power is supplied only when the engine is running? This would make it a LOT easier because I wouldn't have to wire through the firewall into the cabin and all around. Is there one in or around the fuse box somewhere, maybe?

[[SMAN]]

The wire we gave you (yellow with green stripe) gives you power when the engien is running. But you don't want to draw 3 amps through it, so you use the relay and tie it to a power src like the cig lighter wire.

[RDKamikaze]

But is there some wiring area where I can connect the positive to that's in the engine compartment? could I connect it to something in the fuse box, for example? I'm going to get a bosch relay today (12VDC 40W) but I still need to figure out where to connect it.

[[SMAN]]

Anything that supplies 12 volts high amps. So you can just pickup an inline fuse and attach that strait to the battery.


otherwise you attach it to a fused source, such as the cigarette lighter wiring.

[RDKamikaze]

No my kit has a fuse already. I'm talking about for the relay connection. I don't want to have to wire through the firewall because the HHO kit will be in the engine bay. Is there a wire (like the yellow/green one) in the bay that only has positive connection while the car is running? This is the only thing holding me back from installing the kit right now, and I need to find a darned wire lol!

[[SMAN]]

Ohhhh, um good question. Let me trace through the digrams a bit and get back to you in a few.

[RDKamikaze]

Awesome thanks a ton! I can read a manual but I can't follow a wiring diagram. That's my brother's specialty lol! Thanks so much for your help, I'm excited to test it and post results!