The Infamous "Purple Wire"...

Had my stock 2001 Camaro SS harness modified, like alot of LS1 conversion guys do, to a stand-alone style. There is a large,(I'm guessing 12 gauge) purple wire labeled "Starter Solenoid - Keyswitch" that I'm not clear on how it is to be used. Should I just extend its length so it can reach the starter solenoids small solenoid stud, as is...or is it intended to be the trigger wire for a relay, thats powered by keyswitch power?...or what??? I might mention that I have the other "constant 12volt power" & the "keyed power only" harness wires already hooked up & when I turn the key on, there is no voltage indicated at this purple wire. Wiring is not my best attribute, but I'm learning. Thanks again for any help you can give. Gar

Almost forgot to mention...I have an existing factory starter relay in my power center, that has a black & red wire going into it(constant 12 volt & a negative) and also two large purples going into it. One of the purples used to go straight to the starter solenoid I think, and the other purple is labeled that it used to go to a transmission plug that had a bunch more wires on it. Should this relay be tied into the mysterious harness purple wire in question? Thanks, Gar

It sure sounds like the purple wire is supposed to be tied into the starter solenoid wire you're speaking of. The wire will be energized when you turn the key to the "START" position. Use the stock factory large solenoid wire all the way to the starter if you can. Sounds like the wire they added in is smaller than the factory wire.

Purple wire is the one that energizes the solenoid when ign is switched to START position. The truck harnesses have the same color code. That reminds me, I bypassed that relay. :laugh: Need to go back through the electrical box one day... :whack:

PSWired
May 1 2005, 11:20 PM Post #24




I don't know how this works specifically on the F-body harnesses, but typically the purple wire goes directly to the starter solenoid. You'll want this run though a relay to a +12v supply. The relay coil should be hooked up to the crank line from your ignition switch through the neutral start switch on the side of the trans. There should be a yellow wire going into the neutral start switch from the ignition switch and a purple wire coming out going to the starter relay coil.


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1995 Chevy extended cab Z71 Silverado
2002 6L LQ9 Engine, 2001 4L80e transmission

http://www.pswired.com



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Wow!!! Thanks for the great information fellas! Your input along with researching old post info really came through. I went out in the garage immediately & connected the large yellow wire coming out of my main firewall wire bunch(is that called the C-100 connector???) and butt connected it to the existing large purple coming off my trucks existing starter relay(mentioned previously), thats in my power-center and...WALAAH!, SHE CRANKED OVER! Did'nt even have to use the large purple on LS1 harness at all. Thanks again guys. Gar

So you hooked the yellow wire from the truck to the purple wire on the ls1 harness? That will work but you should've been able to go from the purple wire on the LS1 harness to the large purple wire coming out of your fuse box under the hood. If you're going directly into the C-100 you must be bypassing the starter relay unless I'm missing something.

<div class='quotetop'>QUOTE(NITROUS &#064; Jul 27 2006, 05&#58;49 AM) [snapback]59155[/snapback]</div>

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If you&#39;re going directly into the C-100 you must be bypassing the starter relay unless I&#39;m missing something.[/b]

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That&#39;s what I did... and still hadn&#39;t fixed it yet. :lol:

<div class='quotetop'>QUOTE(1BADC10 &#064; Jul 28 2006, 10&#58;26 AM) [snapback]59258[/snapback]</div>

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That&#39;s what I did... and still hadn&#39;t fixed it yet. :lol:
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Me too&#33; And mine is staying the way it is&#33;

Hey, As long as it works right? LOL

<div class='quotetop'>QUOTE(NITROUS &#064; Jul 27 2006, 04&#58;49 AM) [snapback]59155[/snapback]</div>

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So you hooked the yellow wire from the truck to the purple wire on the ls1 harness? That will work but you should&#39;ve been able to go from the purple wire on the LS1 harness to the large purple wire coming out of your fuse box under the hood. If you&#39;re going directly into the C-100 you must be bypassing the starter relay unless I&#39;m missing something.
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NITROUS...Yes, I connected the large yellow wire coming out of the firewall main wire group, which is hot only when you turn the key, to the existing factory starter relay in the power center(the same one used to start the V-6) to one of the two large purple wires coming from this relay. The other large purple coming from this same starter relay went to the small stud on the starter, just as it did on the old V-6. I am now, not using the large purple provided on the modified LS1 harness. Thanks, Gar

Next Wiring Question??? I moved on to the fuel pump relay wiring, using the existing old V-6 relay in the power-center since its already wired up for the most part. The gray wire, black w/white wire, orange wire & the green w/white wire are all still in place coming out the bottom of the relay. The green w/white wire was previously cut from the old V-6 harness & was the only wire needing to be connected, which I did, to the new LS1 harnesses green wire, labeled "fuel pump relay". When I now turn the key, nothing happens. I do faintly hear the computer doing some mild clicking or something when I turn the key back to the off position. I probed the LS1 green wire with a light & it does turn on for about 2 seconds initially, when first turning the key to the start position(not the "on" position) & then turns off automatically. The fuel pump never runs. There is a three wire harness coming from the back of the truck that powers the fuel pump. There is a gray wire(that goes to the fuel pump relay), there is a black w/white wire(that also goes to the fuel pump relay) and there is a light green wire that goes nowhere, because I disconnected it from the old V-6 harness. An old label I had put on it says it went to the main firewall group of wires AND(the wire was split) to an eleven wire plug that went down by the transmission originally. I&#39;m thinking this light green wire goes back to the same fuel pump area & is somehow connected to something that is preventing the fuel pump from running, even though my relay wiring is good to go? I don&#39;t know what this light green wire does, or goes to? Any ideas at all?? Anyone else ever run into this? Oh, by the way, I jumped the fuel pump relay wiring and the fuel pump does work&#33; Again, as always, Thank-You. Gar

Sounds to me like you don&#39;t have the oil pressure switch hooked up correctly. the vortec oil pressure switch is the fuel pressure switch also. You&#39;ll need this for the fuel pump to operate correctly.

Looks like this:
http://www.rockauto.com/ref/ACDelco/12553175.jpg

BTW, You can drill and tap the block down by the oil filter to install this if you haven&#39;t already.

<div class='quotetop'>QUOTE(NITROUS &#064; Jul 29 2006, 10&#58;12 AM) [snapback]59333[/snapback]</div>

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Sounds to me like you don&#39;t have the oil pressure switch hooked up correctly. the vortec oil pressure switch is the fuel pressure switch also. You&#39;ll need this for the fuel pump to operate correctly.

Looks like this:
http://www.rockauto.com/ref/ACDelco/12553175.jpg

BTW, You can drill and tap the block down by the oil filter to install this if you haven&#39;t already.
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NITROUS...I have that same(It looks the same anyway)) sender/sensor/switch at the rear of my intake manifold & its plugged into with a plug from the new harness. The plug is labeled "oil pressure gauge". It consists of only one tan wire going into the plug. At the other end of the harness, where all the labeled wires are hanging, there is a tan wire labeled the same. Could this be the one you mention? Or are you saying I need to install another one and wire it to the light green wire? Is this how your truck is wired, as you must have run into the same situation? Thanks, Gar

Yep, I had to run them both also for the fuel pump to work but there might be someway around it.

The old harness had 4 wires going into this switch. How are you going to read oil pressure?

Check your PM&#39;s

Rewire the relay the correct way. They wire into the LS1 totally different than the old system. The relay has a proper wire diagram on top of it.

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jul 29 2006, 04&#58;09 PM) [snapback]59352[/snapback]</div>

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Rewire the relay the correct way. They wire into the LS1 totally different than the old system. The relay has a proper wire diagram on top of it.
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Yep... Of course, I have a stand-alone fuel pump relay that&#39;s seperate from the stock NBS stuff. I didn&#39;t think that oil pressure sensor did much (at least on the NBS trucks) but send a signal to the gauges telling the driver about pressure. That stock setup on the trucks run from the sender directly to the cluster. I had to pull that, and leave hanging in order to install an aftermarket sender to send a signal to the Autometer gauges.

Talked to NITROUS over the phone yesterday & basically, I am told, that I need a second, additional Vortec oil pressure sensor/switch to control the fuel pump wiring, like the one in the picture above. It should be wired so its between the fuel pump wiring and the relay. Researching the wire colors for this sender now. RedHeartBeat, you had to do this as well? Glad to have others that have already figured this one out, as this wiring stuff drives me crazy, but is fun to learn & understand how these systems work. :thumb: Thanks again, Gar

I have the same type of oil pressure sender but I cut the oil pressure circuitry out of the fuel pump wiring. I basically have a relay that turns the fuel pump on when the PCM commands it to. I don&#39;t give a crap if the oil pressure is there or not. I&#39;m old school when it comes to the fuel pump and oil pressure relationship. The grey wire from the OP wire going to the tank goes directly to the relay. The power side of the switched section of the relay goes to power. I think the PCM triggers ground to the coil in the relay so I have that hooked up and I have 12v constant power going to the on/off coil of the relay.

Basic Bosch relay wiring....

hook connector 85 to 12v constant
hook connector 86 to PCM fuel pump signal lead
hook connector 30 to 12v constant
hook connector 87 to fuel pump wire

There you go, simple fuel pump relay with no interface to the oil pressure switch.

Gar, Here is what I came up with.

Oil Pressure/Fuel sender wiring for Vortec:

Grey - To fuel pump
Orange - Hot at all times
Black - Ground
This will run totally seperate from the LS1 Oil pressure switch.


Fuel pump Control:
Dk Green/White - Fuel pump relay control
Black/White - Ground


Hope this helps, Lance

Thanks a lot fellas...I need to go over my wiring again. :doh: Gar

NITROUS & RedHeartBeat, Well...I went over this fuel pump relay wiring thing again. I could not believe what my problem was&#33; It was the black/w white stripe ground wire coming off the bottom of the relay. It was a bad ground&#33; I&#39;m a putz&#33; Can&#39;t believe it was such a basic thing.(is&#39;nt that usually the case?) Gave it a good ground & the thing fired right up. Ran rough for a couple of minutes & cleared right up. Idles right down & is VERY smooth now. These things have got some good throttle response&#33; For the last twenty-five years I have built offshore powerboats for a living, for companies you may have heard of...Apache, Velocity, Powerplay, etc..I have heard my share of healthy sounding motors with crisp throttle response. These LS1&#39;s are pretty nice running motors, I will say that. :cool: Thanks again guys for all your help. :thumb: Gar

:thumb: Glad you worked it out bro&#33;&#33;

NITROUS, When you get a chance(no hurry) can you get me the part number for that longer 4L60E shift shaft/nuetral safety switch "kit" that you mentioned before? :help: Mucho Gracious. Gar

I&#39;ll see if I still have the box. If not I can get it from the dealership. I know there were 4 different kits offered.

I think this is the part number if I remember correctly. #15724078 I&#39;ll still try when I get home.

Thanks NITROUS&#33; On to temperature gauge function. What did you use for a temperature sender for your factory dash gauge? I was doing a little research & it looks like I just need to go buy a second factory LS1 cylinder head temp sender, which is a two prong sender(?), connect one prong to ground & the other to the dash gauge. Is this the way to go, or??? P.S... Welded up a 2 1/2" dual exhaust, going into a single MagnaFlow dual muffler, to get me around. Sounds much better than open headers&#33; The wife appreciates it too&#33; Thanks, Gar

Call S&P. Tell them you need a 3/8 to 12mm adapter for your factory temp sensor. You can pull the plug out of the back of the passenger side head and mount it there with no problems.

<div class='quotetop'>QUOTE(NITROUS &#064; Aug 7 2006, 03&#58;33 PM) [snapback]60283[/snapback]</div>

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Call S&P. Tell them you need a 3/8 to 12mm adapter for your factory temp sensor. You can pull the plug out of the back of the passenger side head and mount it there with no problems.
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Thanks NITROUS, just ordered it from S & P. Can&#39;t wait to get it. Today I also figured out the trucks oil pressure wire coming out of the C-100, which is tan, and the water temperature wire, which is green, just as you had said. You ground them with the key on & they peg the gauge. Yup&#33; thats them&#33; Next, I need to figure out why my dual F-body fans are&#39;nt coming on at all. The only thing I can think of is, that I have both keyed power wire sources to the relays, both on one supply wire. Would this make a difference? Wish I had more time every day to play with this, it&#39;s getting very close to drive time&#33; Thanks again, Gar