Won't start after wired up

Heres what I have. 96 gmc 1500 that had 5.0/auto. swapped in 03 5.3/auto.
With nelson wiring/pcm hooked up get nothing with the key. If I put power to starter solenoid it will crank but won't start. It is getting fuel because I smell plenty.

Park/neutral safety switch wire isn't hooked up currently. Also the dash isn't showing any position for P R N D 3 2 1.

If I hook the red wire from nelson fuel pump relay wiring to gray wire on fuel pump it still wouldn't start. Fuel pump kicks on whether the red wire is hooked up or not.

Purple wire in nelson harness goes to solenoid. Do we keep the wire to the small terminal on solenoid along with this wire?

Any help would be appreciated.

use the purple wire that was on the original harness to fire the solenoid. Make sure your pink wires are hot with key on and red wire is hot always. Double check your grounds for continuity, you may need a ground from the engine to the chassis if your battery isn't grounded to the engine block. Grounds from the Nelson harness should be grounded to the engine block.

He has a ground wire directly from the battery to the cylinder head.



Your saying the red wire off the fuel pump relay, should be hot, connected directly to battery?


Should there be a ground to the solenoid? He has one hot wire, then he connected the purple wire from the nelson harness to the solenoid, there was a wire on the small terminal already, should he remove that?


And your saying the neutral safety switch only needs to see 12v?

Your saying dont use the nelson solenoid wire, use the OE one?


Sorry bout the rambling questions, I was there with him and my solution was kerosene. :D



thanks

I can't remember the wiring of the nelson harness right off the top of my head but the red wires going to the PCM should have 12v all the time, the pink wires going to the pcm should be switched 12v. The red wire on the fuel pump relay probably should be 12v always, also. Didn't they send a wiring schematic or instructions with the harness?

As long as you have ground, power, ignition, and fuel pump working, you should be able to start the engine (whether you hot wire the starter or not)

Let us know, we'll be here,
allen

They sent instructions for the LS1 electric fan install.

The other info was very vague, the answer may have been there but I didnt see it.

i spent hours trying to find out why mine wouldnt crank.... check your starter relay(should be gray i believe and there should be a purple, black, pink and orange i think?) in the fuse box in the engine bay and the little black wire that goes into it is a ground. mine wasnt grounded. as soon as i grounded it it fired... i must have unhooked it somewhere and not re connected it... took me 2 days to figure that out...also as greg said USE THE FACTORY STARTER SOLENOID WIRE unless you already cut it or something... its much easier.

Yeah, we cut it to use as the wire for the nelson harness solenoid wire....


hes gonna reconnect it see if it will fire.


Why would the transmission position not be illuminated in the gauge panel, any thoughts on that?

Ground the battery to the block, Battery to chassis, block to the chassis, power center to the block, etc. Grounds are critical to all LS engine functions. Solid blacks are battery grounds, black w/white tracers are GM chassis grounds. Nuetral safety switch wire to transmission is not needed to run.

thanks guys. I'll double check and triple check all my grounds.

I know several other people have had issues with the dash indicator not showing which gear, has anyone came up with a solution? I've tried the old gear selector with no change.

[quote=why would the transmission position not be illuminated in the gauge panel, any thoughts on that?[/quote]

It has to be wired with the neutral safety switch to illuminate correctly.

Also, did you wire up the oil pressure switch correctly from the old vortec? It has fuel shut off along with oil pressure, if it doesn't see enough oil pressure it cuts the fuel off. The LSX oil pressure switch just help satisfy the pcm.

the Gauge indicator is powered through the neutral safety switch.
It tells you if your in P R N D 3 2 1
Make sure thats plugged in, for some reason on mine N D 2 1 don't light up.
Good luck..

here is a pic of the switch, it bolts to the tranny.
http://i70.photobucket.com/albums/i1...rtsheaders.jpg

Didn't I just say that? LOL :) Good pic though............

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Originally Posted by NITROUS

Didn't I just say that? LOL :) Good pic though............

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yea you did, i wrote that a long time ago, left my computer and came back noticing i forgot to post it :LOL: :doofus:

I'm just messin with you bro...........................:melissa: BTW, this is RHB hugging you, not me.........:LOL: I haven't messed with him lately either.

Quote:

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Originally Posted by NITROUS

I'm just messin with you bro...........................:melissa: BTW, this is RHB hugging you, not me.........:LOL: I haven't messed with him lately either.

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Dont taze me bro! lol i know its fun to mess around now go make my headers :slice:

I just need my goodies to get here! (Tooling)

:hyper2::hyper2::hyper2:

I didn't hook the 5.3 oil pressure up because I was under the impression it wasn't a must. I just hooked the factory oil pressure up into its place.

Which wire did you hook the neutral/park wire to on the neutral safety switch?

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Originally Posted by 468Blazer

I didn't hook the 5.3 oil pressure up because I was under the impression it wasn't a must. I just hooked the factory oil pressure up into its place.

Which wire did you hook the neutral/park wire to on the neutral safety switch?

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on my swap i took the stock oil pressure sensor off the 1998 4.3 bought the 16mm adapter from Street and performance and removed the 5.3 oil pressure sensor and put the 4.3 one in. that way it reads correctly on your dash. i also used the 4.3 plug. and my pressure seems to read just fine.

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Originally Posted by ChevyLee

the Gauge indicator is powered through the neutral safety switch.

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Not only is it plugged into the nelson harness, he tried plugging it to the old harness, then he took the old part off the original transmission and plugged it into the nelson harness, then into the stock harness....nada.


So it would seem there is a problem elsewhere.


Something else I noticed, the solenoid wire either from the stock harness or the nelson harness, neither get 12v with the key all the way forward (or to engage the starter)......its gonna end up being something simple thats gonna pis me off. :D

Like maybe the power lead that runs to the starter relay has been taken off or the fuse popped?

what year computer did you get?

same pcm out of the 03

On my '96, I wired the large yellow coming out of the C-100 firewall connector, to the large white wire in the LS1 harness, that called for keyed 12 volt. BAM! It started.

Well I hooked the solenoid wire up to a big yellow wire in old harness. It would come on when in crank position. The truck would then crank with key, so believe that is figured out.
Then when I pulled a plug to try and see if I had spark, all I get is the starter solenoid spinning. :speechless: so it looks like I'll be getting a starter tomorrow.
The plugs didn't look good either so will go ahead and replace those as well. Could be the culprit for it not starting.

Yes replace that starter and slap in some new plugs.

If fouled plugs dont fix it, I have the solution, just gimme a call...

http://kissingsuzykolber.uproxx.com/...as_can.med.jpg
http://www.dkimages.com/discover/pre...742/109703.JPG

ok so now it will crank fine with ingition key. But not getting any spark. Is there kind of test I can do on the ignition coils? I've tested and am getting power and ground to the wires to each side of coil packs. The relay to nelson wiring is clicking at was told it should be. Everything now has a good power and ground but no spark.
Any ideas to what to check would be great. Do these engines have any kind of module like the ones with distributors have? That would cause it not to have spark?

It sure sounds like VATS holding you up. Do you have access to someone with HPTuner software that can download your file and see if the VATS is turned off?

There are two other things can can be holding up your spark, one is the cam position sensor on the top of the shortblock at the back behind the intake manifold, the other would be the crankshaft position sensor on the passenger side of the block around the starter location. If either are bad, not connected or have bad or broken wires the engine will not fire. I pinched the cam position sensor wires between the block and transmission bellhousing once and the truck wouldn't start. I then had to repair the wires since they were smashed beyond recognition when tightening the bellhousing. :nutz: