90 sierra rcsb ls swap

Hey everyone, about to do my ls swap, I just got a 5.3 motor and tranny complete from an 05 silverado last week at a good price.

I will be starting my wiring harness soon and had a couple of questions.

1. If i've been reading right the only thing I keep from the old harness would be oil pressure and water pressure and a/c?

2. Since my sierra has the moonie style gauges, how does the speedometer get wired in for the new harness to control the speedometer that's in my truck now?

3. The ses light, does the new harness get spliced in to the wire coming from the sierra pcm? I don't think I really found a definite answer on that from reading around online. Could someone explain how to use the ses light that's already in the dash?

One more thing, do I really need the oil pressure and water sensor adapter or can I get by without adapters using the sensors from my 350 tbi? Wrong size thread i'm guessing is why people use the adapters?

I will try to get as much pics as I can, hopefully some video too.

forgot to add, this will be a standalone harness

Congrats

I can not offer you any advice on the swap as I know shit about harness.

Please while the motor is out I recommend replacing all the gaskets.

Go on PSI there harness starts at 499. I had mine set up with. 80e and ev6 injector pigtails. Almost 600 not to bad. The harness has wires ran so you can run to your factory gauges, but I don't the early 90's gauge so I'm going after market ones. You havd to have the factory cooliant gauge for the ecu. But on summit they sale the fitting kit for the coooliant and oil pressure gauge its like 50 bucks

The true you don't use your serria wire harness if you get from psi. Pull Harness out from the fire wall on the passenger side its a bitch now get a heat gun n it be easier.unhook the four connection under. The dash where your serria pcm is and unbolt the thing that wired going through. And don't cut nothing. All you need alternator red wire battery starter wires and the fat pick wire that hooks to you factory coil.that's all I can think of right now if I can think of some else I let you know

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Originally Posted by fordkiller91

Go on PSI there harness starts at 499. I had mine set up with. 80e and ev6 injector pigtails. Almost 600 not to bad. The harness has wires ran so you can run to your factory gauges, but I don't the early 90's gauge so I'm going after market ones. You havd to have the factory cooliant gauge for the ecu. But on summit they sale the fitting kit for the coooliant and oil pressure gauge its like 50 bucks

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thanks for the info fordkiller but I'm going to go ahead and do my own harness

Here's pics of the motor and tranny. Got the harness removed also.

Good luck..:|

Quote:

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Originally Posted by hotrod

1. If i've been reading right the only thing I keep from the old harness would be oil pressure and water pressure and a/c?

2. Since my sierra has the moonie style gauges, how does the speedometer get wired in for the new harness to control the speedometer that's in my truck now?

3. The ses light, does the new harness get spliced in to the wire coming from the sierra pcm? I don't think I really found a definite answer on that from reading around online. Could someone explain how to use the ses light that's already in the dash?

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1. What you need from the old harness are the wires that go to you gauge cluster. They are oil pressure, and water temperature. For the water temp I drilled and tapped the water pump, probably not the best way but it worked for me. I think I used the LS1 sending unit for oil pressure.

2. For the speedometer to work I used the wires what come from the VSS on the transmission, they disconnect from the rear of the trans and go into the cab. The colors are HI 400 Yellow and LOW 401 Purple.

3. For the SES/CEL, you are going to have to tap it into the corresponding wire that comes from the donor vehicle PCM. And you are also going to need an ALDL/OBD II connector from a 96 or newer GM car or truck.

Quote:

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Originally Posted by Chevy-Art

1. What you need from the old harness are the wires that go to you gauge cluster. They are oil pressure, and water temperature. For the water temp I drilled and tapped the water pump, probably not the best way but it worked for me. I think I used the LS1 sending unit for oil pressure.

2. For the speedometer to work I used the wires what come from the VSS on the transmission, they disconnect from the rear of the trans and go into the cab. The colors are HI 400 Yellow and LOW 401 Purple.

3. For the SES/CEL, you are going to have to tap it into the corresponding wire that comes from the donor vehicle PCM. And you are also going to need an ALDL/OBD II connector from a 96 or newer GM car or truck.

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Thanks man, that clears up the wiring i was wondering about.

You wouldn't happen to know what color wire the ses wire would be would you? Not sure if the wire colors vary from different years.

http://www.lt1swap.com

This website has tons of wiring info on it. It has all the pcm pinouts for all the years. And dont forget that the pcm shows ground for the SES light, not 12v.

Forgot to mention nice looking engine and trans you got. Where did you buy it, local to you?

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Originally Posted by Silverado889

http://www.lt1swap.com

This website has tons of wiring info on it. It has all the pcm pinouts for all the years. And dont forget that the pcm shows ground for the SES light, not 12v.

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Thanks, that's where i've been getting all my wiring info for my stand alone harness.

Quote:

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Originally Posted by Chevy-Art

Forgot to mention nice looking engine and trans you got. Where did you buy it, local to you?

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It wasn't local, it was at the salvage yard, just had to drive about 35 miles to get it, which isn't far. I figured since you lived in san antonio there was tons of salvage yards in your area.

I was planning on getting a motor from ebay, then started adding in shipping and decided it would be cheaper to look at a salvage yard.

Yeah there are plenty, but I am always looking for a place to recommend to someone. Especially if you had a good experience with them.

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Originally Posted by Chevy-Art

Yeah there are plenty, but I am always looking for a place to recommend to someone. Especially if you had a good experience with them.

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check out www.westexap.com that's where I got mine from.

here's a small update, my schoenfeld headers came in today, they're ceramic coated

I started working on my truck getting the old 350 ready to pull out. Also a picture of my truck that i'll be putting the 5.3 in.

Here's a couple pics from today

Attachment 8087Attachment 8084Attachment 8086Attachment 8088Attachment 8089

second set of pics.

Attachment 8090Attachment 8092Attachment 8093Attachment 8094

When u fiqure out the ses color let me know I'm working on a 90 as well. I will let u know If I can find it also.

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Originally Posted by tempoffroad

When u fiqure out the ses color let me know I'm working on a 90 as well. I will let u know If I can find it also.

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ok will do

I got the motor and tranny pulled out, now it's time to clean up the old wiring.

Attachment 8098Attachment 8099

I've done some modifying to my truck harness, but still unsure of which wires are what, the wiring diagram I have doesn't say where they go or unless i'm blind and just can't see it on my diagram.

What all is on the junction block on the firewall, not sure if one is my fuel pump relay or not. I've traced some of them and some of them go into the block in my last pic.
Attachment 8123

Can I remove this egr metal line that goes on the frame rail?
Attachment 8122

Does this connector go to the instrument cluster?
Attachment 8121

I'm guessing this one goes to my instrument cluster of fuse box also?
Attachment 8120

The power block supplies alot of the interior power. I left mine intact to simplify engine installation. The fuel pump relay can also be reused but must get actuating power from the new PCM.

The second pic shows what I believe to be the charcoal canister line. My 6.0 had a port to scavenge fuel vapors from the tank so I hooked mine there.

Not sure of the connector in the third pic. Could go anywhere.

Fourth pic shows firewall connector. Should go to convenience center under dash. At least that where mine goes in my '93. Convenience center supplies power to accessories like power windows and door locks.

A comprehensive wiring diagram is almost a must for any kind of job like this. I found mine on Ebay. Here are some for your truck:

http://www.ebay.com/itm/1990-Chevy-S...250d3e&vxp=mtr

http://www.ebay.com/itm/1990-GMC-R-V...6985c0&vxp=mtr

http://www.ebay.com/itm/1990-90-Chev...e6df1d&vxp=mtr

http://www.ebay.com/itm/1990-90-Chev...fcc556&vxp=mtr

http://www.ebay.com/itm/1990-90-Chev...a0d5fe&vxp=mtr

http://www.ebay.com/itm/1990-90-GMC-...87497e&vxp=mtr

Quote:

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Originally Posted by Mickeymotormount

The power block supplies alot of the interior power. I left mine intact to simplify engine installation. The fuel pump relay can also be reused but must get actuating power from the new PCM.

The second pic shows what I believe to be the charcoal canister line. My 6.0 had a port to scavenge fuel vapors from the tank so I hooked mine there.

Not sure of the connector in the third pic. Could go anywhere.

Fourth pic shows firewall connector. Should go to convenience center under dash. At least that where mine goes in my '93. Convenience center supplies power to accessories like power windows and door locks.

A comprehensive wiring diagram is almost a must for any kind of job like this. I found mine on Ebay. Here are some for your truck:

http://www.ebay.com/itm/1990-Chevy-S...250d3e&vxp=mtr

http://www.ebay.com/itm/1990-GMC-R-V...6985c0&vxp=mtr

http://www.ebay.com/itm/1990-90-Chev...e6df1d&vxp=mtr

http://www.ebay.com/itm/1990-90-Chev...fcc556&vxp=mtr

http://www.ebay.com/itm/1990-90-Chev...a0d5fe&vxp=mtr

http://www.ebay.com/itm/1990-90-GMC-...87497e&vxp=mtr

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Cool man, thanks for the info, on the charcoal canister line i don't think i need it since i will be deleting the evap.

Also i don't know why i was wondering about the fuel pump relay since my stand alone harness will have one on it.

Well i went ahead and ordered me a harness from psi and it finally showed up. These guys did a damn good job on the harness.

I'm hoping to have the 5.3 dropped in this weekend.

Anyway, heres a pic of the psi harness.

Attachment 8126

That's a nice looking harness. Their workmanship looks impressive.

My budget kept me from going that route. I had to rework the original harness I got from the donor truck. Definitely more time consuming than the "Plug and Play" setup you have. By reworking the original harness, I feel it gave me a broader understanding of the entire system needed to get one of these engines to live in an older pickup.

Keep up the good work and keep the pics coming.

Here's my camaro temp sensor and pigtail i got in the mail today, i'll have a cleaner install and look with this option.

Attachment 8127

you happen to have a part# for the 3 wire camaro sensor and plug?

http://www.hawksthirdgenparts.com/pr...onversion.html

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Originally Posted by smkur50

you happen to have a part# for the 3 wire camaro sensor and plug?

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well gagliano7 replied to you before i could, but here's the part numbers just for reference
coolant sensor 12551708
sensor pigtail 12102748