Key start power wire?

cosmo22nov

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Joined
Jun 11, 2007
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Ok so I'm wiring up a relay on my 99 and I need to know what wire to tap to get power only while cranking.

Thanks
Tanner
 
Wow now I feel dumb! But I was thinking, how many amps run through that wire? I only have a 30amp block relay. And sorry if these are stupid questions, I'm wiring retarded...
 
It doesn't matter what kind of amp draw that wire is rated for. That's why you have the relay. All you'll be robbing from that wire, as far as amperage goes, is whatever it takes to energize the coil in your new relay (which is negligible.) Since your relay is rated for 30 amps, then that is the amount of load you can run through it (pending your wire is properly sized.) Basically you're taking a hot wire (I'm assuming from your battery) and running it through your relay, then hooking it to your new accessory (essentially eliminating any additional load on the wire you're tapping.)
 
Ok so I'll be using this for a 1500 12v/47re swap. Im using the factory 1500 gasser wiring. The ecu needs to see a cam and crank signal during startup for everything to work right. So this is where the relay comes into play. So Im planing on robbing the cabl signal to simulate a cam signal. I drew up a diagram, should this do what I'm wanting?

CamSensorRelay.png
 
I don't know the details on what kind of signal the ECU is looking for, but it must not be too picky (assuming you've already researched that part.)

As for the relay wiring, that should work if it's constantly looking for the crank sensor and only looking for the cam sensor while cranking.

Just out of curiosity, what are you trying to do with the "cut cam sensor wire and connect to wire from fuel shut off relay?"
 
I'm using a fuel shut off relay for this, it's not actually going to the fuel shut off relay. But thanks for your help, that's all I needed to know
 
And just to double check I tap the small wire going to the starter not the big one correct?
 
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