Running multiple things off the ecu circuit?

[hatchet9mm]

I plan on running a map ecu, and I was wondering if I would be able to use the 12v ignition source for the ecu to power the map ecu as well as my wideband or if it would put too much load on the circuit? I'm not an EE and was hoping to hear from all of your experiences and know why it would or wouldn't work.

 

[Poodles]

Relays...use them

 

[hatchet9mm]

I just watched a how to on relays, but I'm still a bit confused. I want my wideband running the entire time as well as my fuel controller, if I used a relay and it's on all of the time doesn't that negate its purpose. I don't doubt that it may work, I just think I'm missing something.

 

[hvyman]

If you leave them on all the time they will kill your battery.

Relay just gets a signal from smaller circuit and uses power for the component from a better source like the battery.

 

[hatchet9mm]

The power source is the 12v ignition on, so if the car was off it wouldn't drain the battery right? So I get the power directly from the battery and have the "switch" for the relay powered by the ignition switch? Thank you very much for the wiring/engineering lesson.

 

[hvyman]

The relay has 2 parts.

A magnetic coil that gets energized from a 12v switch source like the ignition. Other side gets grounded.
And the switch that gets closed when the switched power energizes the coil. which one side would be from the battery and the other side to a safc or wideband.

 

[hatchet9mm]

Right, then my next question is what is the best way of going about finding or making the battery source. Have you guys added and routed a wire directly from the battery to do this or is there another appropriate battery source closer to the ECU area, I'm just trying to find the easiest way to wire in my wideband and Map Ecu, using my patch harness if that matters any. I know I sound noobish, doing the wiring itself is therapeutic in a way. Understanding it on the other hand is like Chinese to me.

 

[jetjock]

The Chinese put out electrical fires the same way we do...

 

[hvyman]

B+ is at the ecu. Its one of the main power wires for the ecu and some of the engine sensors.

 

[hatchet9mm]

B+ is what the Map ECU told me to splice into to power it, So I need to run another relay using B+ to power the magnet, and a battery source to run the wideband. I don't want electrical fires, that's why I started the thread.

 

[hvyman]

No it would be ign to power the relay and source from b+

 

[hatchet9mm]

Okay, and I'm guessing the MAP ECU has a relay in it so I just have to relay the wideband, or would it be worth it to relay the MAP ECU too.

 

[hatchet9mm]

Okay, use B+ as signal or commonly known as (W1) on the relay, then I guess I am going to run a wire from the battery as the power source or (C1) for the wideband.

 

[Poodles]

With a fuse of course...

 

[hatchet9mm]

And just to make sure, it would be a bad idea to tap the battery wire that pins in the ECU. I just hate the idea of running an unloomed wire from the battery, but its better than my car catching on fire.

 

[jetjock]

You're making this way more complicated than it needs to be. The loads are minimal. Connect directly to B+ or the IG1 line. Fuse at the source.

 

[hatchet9mm]

Does any one know what the amp draw for the ecu is. Trying to determine the size fuses I'm going to run.

 

[SC61 MK3]

You need to figure out the amp draw of what you are running the power to. I would wire the map ecu to the ecu like it says and wire the wideband up from the heavy gauge ignition wires

 

[hatchet9mm]

The nominal amp draw for the ecu is 1a the nominal draw for the wideband gauge is 1.3a and the heater circuit for the sensor is 1.2a so I don't know if the total draw is 2.5a or 1.3a cause the gauge powers the sensor. In any case the total draw is between 2.3a and 3.5a

 

[SC61 MK3]

I would try to limit the amount of things wired into the ecu to as few as possible. Unless it specifically says to wire into the ecu go elsewhere. That being said if you don't understand how a simple relay works then the best thing to do is tap into the heavy gauge ignition wires and fuse it as close to where you tap in as you can.