Ignition "Start" Signal for LS1 wiring Question

[UofA_ZCar]

I've read a lot and PM'd a few people with questions regarding wiring my LS1. I've appreciated the help as wiring is the part of the build I have been least excited about.

 

 

Off the ignition switch I have two wires that get power in the "start" position. One is green with white strip and one is black with a white strip. Why are there two getting power and does it matter which I use to give that signal to the PCM? I believe the PCM needs a ignition on signal and a start signal correct?

 

I'm also confused about the white wire that is by the black/yellow wire that give the start signal to the starter solenoid. What do I attach it to? Every thing I have read says to attached the white/Red wire (that used to attach to the L28 alternator) to 12V power from the starter post, but when it do the white wire has constant power also. Was the white wire the 12V positive power to the starter on the L28 and can just be capped off now?

 

White Wire:

 

White/Red wire:

 

If I have missed this in a previous thread please feel free to link the thread.

 

Thanks

Edited October 8, 2012 by UofA_ZCar

[240z72]

Are you talking about the z car wireing for the ignition switch? If so what z car are you using? and what year?

[UofA_ZCar]

Are you talking about the z car wireing for the ignition switch? If so what z car are you using? and what year?

 

 

yes z ignition switch wiring and body wiring harness. The wiring is for a 1973 240z.

[UofA_ZCar]

 

 

Off the ignition switch I have two wires that get power in the "start" position. One is green with white strip and one is black with a white strip. Why are there two getting power and does it matter which I use to give that signal to the PCM? I believe the PCM needs a ignition on signal and a start signal correct?

 

 

 

I figured out the answer to this question. You use the Black + white strip wire for the PCM connection because it has power with the Z ignition in the "on" and "start" position.

 

 

I still need help with what to do with the white wire (from the z body harness) that is by the starter solenoid wire.

Edited October 8, 2012 by UofA_ZCar

[240z72]

The white wire I think 10 guage wire is what feeds the cab for power. All cars and trucks take the cab feed power from the positive terminal on the starter.

Edited October 8, 2012 by 240z7273

[RebekahsZ]

I'm out of town. If you don't get it figured out, call me Monday night and ill look at my car while we talk. My memory is foggy. 256-366-4685. I think I used the Datsun starter wire to the LS starter wire. I found a wire under the hood that was on only in the ignition on key position as a switch "on" wire to a solenoid on my new fuse block to power the switched circuits. Then I used a wire directly off the battery for the few constant on circuits. I didn't have to cut into any wiring on the ignition switch or chassis fuse block. Don't know if my way was best but it works.

[UofA_ZCar]

The white wire I think 10 guage wire is what feeds the cab for power. All cars and trucks take the cab feed power from the positive terminal on the starter.

 

 

ok. So then I can disregard the charge wire (white/red strip) that attached to the L-series alternator.... so long as I run the LS1 alternator charge wire to the positive post on the starter, then onto the positive batter post. Per the second post of this thread:

 

http://forums.hybridz.org/index.php/topic/77180-ls1-alternator/page__p__734448__hl__%2Balternator+%2Bwires+%2B__fromsearch__1#entry734448

 

 

Thanks for all the help.

[240z72]

Ya thats the basic power setup for most cars n trucks.. I personally havent had to deal with it yet as im not there in my build but I think the altertor needs a resistor because I think if you give it 12v it will fry it . Dont quote me its just what ive read. I dont know anything more about it yet. But id look into it befor you ruin your alternator. Goodluck.

[GOTHALOSISM]

I'll be over there on the 20th so we can get it running for ya. I might be able to talk my wife into letting me bring my LT1 z to show yours what they are like

[RebekahsZ]

No, the white wire with the red stripe goes from the starter to the fuse block inside the car on the transmission tunnel. That is how you get power to your lights and things associated with the chassis. Get your voltmeter and check for ohms between the white/red wire on the fuse block and the wire you are asking about. You can still call me if you need me, just make it after 7pm.

[240z72]

In the pic he posted the white and red wire is the positive lead off the alternator. All those are alternator wires. If in fact that is the one your talking about. There is another white wire in the top pic (I donk know if that has a red stripe) that is the one that feeds the cab.

[wfritts911]

Make sure you wire a resistor between 12 volts and the alternator. Or if you are stranded somewhere about an hour from home, the fasten seat belt light works as well . I think all the white/red wires on my car went to the maxi fuses coming off of battery 12v. Although I think the Z goes from the battery to the starter, then the starter to everything else, or at least thats how I was told. Also make sure you check what wires you are using to feed the PCM ign power, make sure they don't lose power when you turn the key to "start"...cause if they do you will spend forever trying to figure out why it doesn't start . Also I'm pretty sure the PCM doesn't need to see a "start" signal, just make sure the 5 or 6 wires are getting fed positive "ign" power(Plus the one BAT wire). And ground everything out and turn the fuel pump on, and it should fire right up.

 

-Will

 

EDIT: If your PCM is 99+ your alternator wire should be in your harness coming from the PCM, so you shouldn't need to do anything but plug the plug in. If its a 98, don't assume you can just plug the plug in and be done, it goes nowhere

Edited October 11, 2012 by wfritts911

[cheesepocket]

Wfritts is correct, in my '98 LS1 with '98 PCM the computer must know when you're cranking the starter by reading the input from the reluctor wheel, so it starts firing the injectors and coils to get it to start. I didn't connect anything to my PCM to tell it I'm attempting a start.

 

I put a high-current pushbutton starter from Jegs or Summit right into the hole that the cig lighter used to occupy, and simply ran that wire that used to be on the key switch through that new pushbutton, and of course tied that factory Datsun wire to my LS starter.

 

I put shrink tube over my old Datsun alternator connectors and tied them off, and ran the big red power wire from the alternator to the starter post, and the smaller "sense" or "excitation" wire through a 350 ohm resistor (using solder and shrink tube to keep it clean and reliable)to a +12 VDC keyed on source.

 

I used two power junctions under the hood, one for constant 12 VDC power and one for keyed power. I bought them from delcity.net which has a whole bunch of supplies to do clean wiring with.

 

Good luck, the wiring isn't much fun, but it is rewarding when everything works without the smell of burning insulation.