Can I bypass my LS harness to wire the starter?

[Nodnarb76]

I'm now in month four of my LQ4/4L80 Swap into my 87 Suburban, and have had something strange happen. For the past 3 months everything has been fine, with all the wiring connected like it is supposed to be I could turn the key and get the motor to turn over but not start because I didn't have my fuel lines connected.
Yesterday I connected my fuel lines and went to start it for the first time and now the truck won't turn over at all. I have fuel pressure, the throttle body opens when I press the gas pedal, so I know I have power to the ecu.
I broke out my multi-meter and verified I have 12v at the starter wire coming from the ignition. When I checked for voltage at the starter solenoid with the key in the start position I get nothing. Because the truck has been down for a few months, I tried connecting some jumper cables to another car incase I had a dead battery, nothing changed. I checked for wires that my have come disconnected and the only one I found is was the power wire for my torque converter lockup. Since it was late at that point and all my tools were put up I haven't fixed that wire yet. I don't think that would have any effect on not being able to turn the motor over would it? Does the brake pedal need to be pressed to start the motor?
Because I can always get 12v from the purple ignition wire, can I just wire that directly to my starter solenoid and bypass my LS harness?
I still have the neutral safety switch intact on my steering column, that I believe the ignition wire has to go through first.

[72MARIO]

could the injectors have stuck open and hydro locked the engine ?

[Nodnarb76]

Originally Posted by 72MARIO

could the injectors have stuck open and hydro locked the engine ?

Would that prevent power from getting to the starter?
How would I fix this?

[72MARIO]

I have 12v at the starter wire coming from the ignition.

I am a little confused.... Do you have power at the purple wire hooked up at the starer when the key is turned forward to start position ?

You can use any source of power to energize the starter solenoid. If the original starter wire is available that would work as well.

[Nodnarb76]

Originally Posted by 72MARIO

I am a little confused.... Do you have power at the purple wire hooked up at the starer when the key is turned forward to start position ?

You can use any source of power to energize the starter solenoid. If the original starter wire is available that would work as well.

I do NOT have 12v at the starter when key is turned to start. But I DO have
12v at the purple wire coming from my ignition/neutral safety switch where it plugs into my LS harness. Some reason I am losing power between the starter and the starter wire coming from the ignition. What in an LS harness would stop power from getting to the starter?

If all else fails, I will just connect the purple wire directly to the starter. But I sure would like to know why all of a sudden the truck won't turn over when It would 100% of the time for the past 3 months until yesterday.

[Nodnarb76]

By the way, thank you for the help/suggestions! This forum is what has made my LS swap possible, with all of the knowledge everyone has! Hope to be able to help others someday like people are helping me!

[72MARIO]

I am not sure what happens there with the ls wiring side... I was just going to use the original purple starter wire in my truck

[compsystems]

It depends on what harness you used and how its wired. Do you have a starter relay and fuse in your harness? That would be the first thing I would check.

without knowing more about your setup its hard to say where to look next.

[Nodnarb76]

Originally Posted by compsystems

It depends on what harness you used and how its wired. Do you have a starter relay and fuse in your harness? That would be the first thing I would check.

without knowing more about your setup its hard to say where to look next.

I'm not sure if there is a starter relay or not. The harness is from LSX4U FWIW.
realize it's impossible to fix something like this over the internet or phone, but I sure am getting some good info on things to look for and try, thank you all.
I will try and see if I can find a bad relay. If not, I'd like to run the purple starter wire (that I know has 12v in the crank position) directly to the starter if everyone thinks that will be ok.

[compsystems]

I have my ignition switch purple wire connected directly to the starter on my LS motor.. That's the way it was factory with a 350 starter. 5k miles later still works.
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[First c10]

Most reworked and custom built harness for the LS swaps do not integrate the starter wire.(well not that I have seen) most say 5 wire hook up and not 1 of them is the purple starter wire... On my swaps I used the purple wire form the factory reworked LS harness because it has the correct pigtail for the starter and is already in the loom and ready to install but connected the opposite end to the firewall purple wire from the fuse block. Hope this makes sense.
Scott

[clinebarger]

Make SURE the TRANS is in PARK!!!! I understand you have a Column mounted NSS Switch, But if the LS harness is equipped....It is Trans mounted.

What year engine & harness? Rewired Factory Harness or New Harness?

Do you have a Neutral Safety Switch mounted over the Manual Shift Shaft? Is the Engine Harness plugged in NSS Switch.

[Nodnarb76]

Originally Posted by clinebarger

Make SURE the TRANS is in PARK!!!! I understand you have a Column mounted NSS Switch, But if the LS harness is equipped....It is Trans mounted.

What year engine & harness? Rewired Factory Harness or New Harness?

Do you have a Neutral Safety Switch mounted over the Manual Shift Shaft? Is the Engine Harness plugged in NSS Switch.

Engine and harness is a 2004 lq4 with 4L80E.
Reworked harness from LSX4U.
Neutral safety switch is mounted on the shift shaft comming off the trans. And the connector is plugged in.

I have 12v going into the starter wire on the harness and no voltage at the starter end comming out of the harness. It was turning over fine every week for the past 3 months. The after installing my radiator and hoses, and fuel and trans cooler lines, it wouldn't turn over. Made sure battery was charged, and spent hours making sure no wires came unplugged.

Thanks for the help!

[72MARIO]

I think clinebarger is onto something there. We had a bad starter relay in our 2005 tahoe that took a while to trouble shoot. The weird thing you dont expect to go wrong do..

[clinebarger]

You can bypass, Just make sure the shifter is adjusted correctly & the Trans itself is in PARK.