LS Wiring Troubles.

[Anubis]

The stand alone harness I bought from lsx4u.com only needed like 6 wires connected to it from the old harness. I really don’t know what this guy was doing.

A good stand alone harness should include fuses for all the pink power wires (switched power) for ECM, injectors, o2 sensors, etc. and constant power to ECM. Have you located these fuses and checked for power there?

This is why I make my own harnesses. People pay for a plug and play solution but get cookie cutter junk. You can easily make your own with on line documentation. Stand alone harnesses do not always integrate well into a vehicles electrical system and compromises are often made that require weird wiring solutions to make them work..

 

[Jglew82]

Okay so I posted a video on YouTube to kind of show what’s going on

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Oops, my bad, for some reason I thought you were originally TBI.

There should be a ground going directly to the engine from the negative terminal, and also one from the battery to the body. You can leave the long connection from the body to the cylinder head, as that will act as a ground strap, but you really need a good, solid, large ground connection directly to the engine block/head.

Are you getting power to your fuse block? I would re-do the power cables to have: Battery to starter, battery to alternator, alternator to fuse block. You don't generally want to crowd the alternator terminal because it will invite corrosion if the boot can't completely cover it. It does look like you have a rusty alternator terminal, so check that and clean it up if it's rusted.

Get power back to your truck and wired properly as per above first and start troubleshooting the LS mish-mash after. Go to lt1swap.com and dig up the pinouts and diagrams and go through them one by one. Sorry you're having to deal with this.

 

[Bm1912]

A good stand alone harness should include fuses for all the pink power wires (switched power) for ECM, injectors, o2 sensors, etc. and constant power to ECM. Have you located these fuses and checked for power there?

This is why I make my own harnesses. People pay for a plug and play solution but get cookie cutter junk. You can easily make your own with on line documentation. Stand alone harnesses do not always integrate well into a vehicles electrical system and compromises are often made that require weird wiring solutions to make them work..

Here’s a video showing the standalone harness I have

xc_hide_links_from_guests_guests_error_hide_media

 

[Bm1912]

Oops, my bad, for some reason I thought you were originally TBI.

There should be a ground going directly to the engine from the negative terminal, and also one from the battery to the body. You can leave the long connection from the body to the cylinder head, as that will act as a ground strap, but you really need a good, solid, large ground connection directly to the engine block/head.

Are you getting power to your fuse block? I would re-do the power cables to have: Battery to starter, battery to alternator, alternator to fuse block. You don't generally want to crowd the alternator terminal because it will invite corrosion if the boot can't completely cover it. It does look like you have a rusty alternator terminal, so check that and clean it up if it's rusted.

Get power back to your truck and wired properly as per above first and start troubleshooting the LS mish-mash after. Go to lt1swap.com and dig up the pinouts and diagrams and go through them one by one. Sorry you're having to deal with this.

So what I need to do first is get power to the inside of the truck and then worry about the harnesses?

 

[Bm1912]

Oops, my bad, for some reason I thought you were originally TBI.

There should be a ground going directly to the engine from the negative terminal, and also one from the battery to the body. You can leave the long connection from the body to the cylinder head, as that will act as a ground strap, but you really need a good, solid, large ground connection directly to the engine block/head.

Are you getting power to your fuse block? I would re-do the power cables to have: Battery to starter, battery to alternator, alternator to fuse block. You don't generally want to crowd the alternator terminal because it will invite corrosion if the boot can't completely cover it. It does look like you have a rusty alternator terminal, so check that and clean it up if it's rusted.

Get power back to your truck and wired properly as per above first and start troubleshooting the LS mish-mash after. Go to lt1swap.com and dig up the pinouts and diagrams and go through them one by one. Sorry you're having to deal with this.

I’m going to find more long negative wire to mount on to the motor. Where do you suggest I put it? Also. I’m fixing to find my meter to see if I have power going to the fuse box or not.

 

[Jglew82]

So what I need to do first is get power to the inside of the truck and then worry about the harnesses?

You have a lot of issues going on, and a major one is you have no power inside your cab. This is where I would start, yes.

I’m going to find more long negative wire to mount on to the motor. Where do you suggest I put it? Also. I’m fixing to find my meter to see if I have power going to the fuse box or not.

I have mine mounted to the block on the passenger side front, directly from the negative battery terminal, and also one smaller gauge one from the inner fender (stock location) to the battery negative terminal. There should be a few open 10x1.5 threaded holes available to place a ground to on either side of the block, it doesn't really matter. Just be sure it is good and solid, clean and free of paint/rust.

 

[Bm1912]

Okay. So I check my battery wire all the way up to the fuse box and it runs 12.5 volts. I am looking at the old wiring harness and I noticed that there are two black wires cut that are coming from the inside of the truck

 

[Bm1912]

They’re both black with a white stripe one is a tad thicker than the other. I don’t know why they’re cut.

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[Jglew82]

Those should be grounds. This may explain why your instrument panel isn't powering up. Connect them both to ground and see if you get power inside.

 

[Bm1912]

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I actually found the solution this box was only somewhat put on there I pushed it on and heard power go through the truck. Now I need to figure out how to get it to crank.