Ok I know you are going to say look at the wiring diagram for the car and I have done so. I have some specific questions though. I am wiring up a relay for my wideband so that it only comes on when the ignition comes on so that I don't have to turn it off when I get out of the car. I would tend to forget as I have it mounted in the rear bin.

I am was looking diagram I-1 in the electrical wiring schematic. The wire labeled P (Purple maybe?) comes from the ignition switch through a relay to the defrost switch and then to ground on the other side of the switch. I assume that when the defrost switch is turned on it grounds the relay in effect turning it on. Since my relay and wideband are both grounded on the frame wouldn't the P wire on the switch be live whenever the car is on? I am just looking for a trigger for my relay, not a full on power source. I get the power for my wideband directly from the battery (In driver side bin) as to give it as much power as possible because I was having voltage issues with the cigarette lighter.

Long story short I was planning on tapping into the wire labeled P to use as a trigger for my relay. Will this work?

 

I think I found a flaw in my thinking. If I take the power off this wire in front of the switch won't the wideband relay in turn ground the defrost relay and turn it on. Am I right thinking this?

 

any switched wire will turn on the relay. gound one side of the relay coil. put the cigg pos on the other side of the relay coil and splice the wire off the battery to the 2 switched poles on the relay. make sure the relay is rated for the amp draw 30amp relay can be had at radio shak

 

I'm not sure if the wire labelled P will have 12V switched through ignition because of the presence of the ECU in that circuit. That said, even IF it does have 12V switched through the ignition, patching into the P wire won't work. When you turn on the rear window defroster switch, you will be grounding wire P which will turn off your wideband relay. You would want to patch into the B/Y wire between the rear window defroster relay and the fuse. That would work, as it would always see 12V with ignition on regardless of the state of the rear window defroster switch.

BUT why don't you just use the cigarette lighter circuit? It's switched, and can easily provide enough current to switch on a relay. (I think you said you had voltage issues with the cig lighter circuit, but I took that to mean you were trying to power your wideband through it, rather than just using it to trigger the relay)

On a side note, I needed a switched 12V source to power my water temp gauge. Seeing as I was already taking wires from the engine bay I used the low amp 12V feed to the fan relays.

 

No, but as I said before - turning on the rear window defroster switch will ground the wire labelled P and hence turn off your wideband relay if you patch into the wire labelled P just above the rear window defroster switch.

 

See page 4 of this document:

http://www.davidgeesaman.com/rx7/Wat...%20Install.pdf