5.3 wiring basics
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On The Tree
Joined: Mar 2006
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5.3 wiring basics i have a 2001 5.3 complete pull out and a friend with hptunners. What wiring pinnout do i need to use to eleminate the un needed wires so that i may make the engine run. is there a difference from ls1 to 5.3 computer, also wiring. and if i decide to who could i send my harness to and have it fixed to work in my truck..
1985 k10 4x4
2001 5.3 pull out
350 turbo.
1985 k10 4x4
2001 5.3 pull out
350 turbo.
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
You don`t so much need a pinout to figure out what you need and what you don`t, you more need to know what you need/want and then find the wires that you want to get rid of. What was your motor pulled out of? Do you need to be emissions legal? If you don`t do you want to eliminate ALL emissions components or just some? Are you using A/C and if so what style? I have posted some wiring info in the FAQ section for the truck 5.3L`s. I also have wiring diagrams that I can send you via e-mail if you PM me your address.
On The Tree
Joined: Jan 2006
Posts: 172
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From: Quakertown, PA
On the other hand, if you are keeping all the controls on the engine intact, you may want to concider using the underhood fuse block. I just finished wiring up my 5.3 in my Jeep. There are literally three wires to connect to the stock wiring: start circuit, 12v supply, and 12v switched. The underhood fuse block contains all the relays you need, and controls most of the switched outputs through a onboard relay...
Joined: Sep 2004
Posts: 3,148
Likes: 12
From: Downers Grove, IL
If I would have known it was that easy I would have used the underhood fuse block. But oh well I ended up with a smaller fuse/relay center that I had a place for under my hood. But if I had known it was that easy at the time........ On The Tree
Joined: Jan 2006
Posts: 172
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From: Quakertown, PA
It surprised the hell out of me too. Took me six hours of studying the electrical diagrams, and 15 minutes of soldering. 
Eventually I want to rewire the entire truck with the Chevy truck harness and eliminate the stock fuse box, but that will be a future project...
Eventually I want to rewire the entire truck with the Chevy truck harness and eliminate the stock fuse box, but that will be a future project... Thread Starter
On The Tree
Joined: Mar 2006
Posts: 134
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thanks for the help, i have about 7 hours of studying the wiring on the 5.3. it is just intimidating at first but after a few hours i am getting the hang of it. i have elimenated all the emissions, egr, ac, and unwanted from the harness. i wish i had the factory fuse center but my connector was cut. my email is kingscustoms@verizon.net
Originally Posted by jeepinpete
On the other hand, if you are keeping all the controls on the engine intact, you may want to consider using the underhood fuse block. I just finished wiring up my 5.3 in my Jeep. There are literally three wires to connect to the stock wiring: start circuit, 12v supply, and 12v switched. The underhood fuse block contains all the relays you need, and controls most of the switched outputs through a onboard relay...
I did a wiring conversion diagram for the GM LS1 harness for my Supra, the lo-res version is here. The hi res (1.6MB) version is here.
It looks like there are not too many power in requirements for this motor, and I suspect the LM7 will be similar.
EDIT:
Pic of what I'm referring to:
EDIT #2
Found this FS on Ebay, looks like it's what I need, for $30 can't go wrong:
Last edited by V8 Supra Builder; Jun 3, 2006 at 10:30 PM.
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Joined: Sep 2004
Posts: 3,148
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From: Downers Grove, IL
I used 8 fuses for my LM 7 swap, computer constant power, computer ign power, computer ignition power 2, coils even, coils odd, front o2, fuel pump, and MAF.
I don`t know if the upper part of the connector is available, I think that may be part of the fuse center. I just cut that connector off and put a couple Weatherpack connectors on.
I don`t know if the upper part of the connector is available, I think that may be part of the fuse center. I just cut that connector off and put a couple Weatherpack connectors on.
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Staging Lane
Joined: Feb 2006
Posts: 69
Likes: 0
5.3 harness
Originally Posted by jeepinpete
On the other hand, if you are keeping all the controls on the engine intact, you may want to concider using the underhood fuse block. I just finished wiring up my 5.3 in my Jeep. There are literally three wires to connect to the stock wiring: start circuit, 12v supply, and 12v switched. The underhood fuse block contains all the relays you need, and controls most of the switched outputs through a onboard relay...
I sent a pm for you on this 5.3 under hood fuse block. sounds like a winner.
On The Tree
Joined: Jan 2006
Posts: 172
Likes: 0
From: Quakertown, PA
More info...
The truck under hood fuse block (ufb) has about 8 connectors that plug into it from the underside. One, pictures above by V8 Supra Builder, comes from the the engine harness. There is another that looks just like it that come from the dash harness. There are also two smaller versions of that plug, one which comes from the dash harness, and one that goes to the front lighting harness.
The only complication with the three wire hookup is that you need both the dash connectors. I don't have the pinouts in front of me, but I will get that info and post it. The larger connector uses two wires (start and fuel pump supply), and the smaller uses one wire (12v switched, IIRC).
There are also a couple 1 and 2 pin connectors that plug into the UFB. One of these has two 10ga wires which are fused through the maxifuses, 50 amps IIRC. I used one of these circuits to supply 12v constant to the ignition switch. This works very nicely with the Jeep's wiring harness, since it pretty much duplicates the original schematic.
I will look in my manuals tonight and post which pins are used...
The truck under hood fuse block (ufb) has about 8 connectors that plug into it from the underside. One, pictures above by V8 Supra Builder, comes from the the engine harness. There is another that looks just like it that come from the dash harness. There are also two smaller versions of that plug, one which comes from the dash harness, and one that goes to the front lighting harness.
The only complication with the three wire hookup is that you need both the dash connectors. I don't have the pinouts in front of me, but I will get that info and post it. The larger connector uses two wires (start and fuel pump supply), and the smaller uses one wire (12v switched, IIRC).
There are also a couple 1 and 2 pin connectors that plug into the UFB. One of these has two 10ga wires which are fused through the maxifuses, 50 amps IIRC. I used one of these circuits to supply 12v constant to the ignition switch. This works very nicely with the Jeep's wiring harness, since it pretty much duplicates the original schematic.
I will look in my manuals tonight and post which pins are used...
Staging Lane
Joined: Feb 2006
Posts: 69
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connectors I think these are the connectors. The small square green one which is not shown is for the front lighting. The small square red one has a gray wire which I beleive feeds 12 volts to the feul pump. Also have the fuel quantity sender on that red connector. The two large rectangle connectors is were I get LOST. One is with the engine and one comes from the dash.
On The Tree
Joined: Jan 2006
Posts: 172
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From: Quakertown, PA
I didn't get time last night to get out the manuals, but the pictures you posted show what you need. The green connector isn't necessary, and there is one wire from the red connector which as you stated is for the fuel pump. In the first picture, the two wire connector next to the large grey connector is 12v supply to the ignition switch. Either wire can be used, as they are both fused. The engine harness connector I left alone. Finally, I will post the wires I kept from the dash harness connector...
On The Tree
Joined: Jan 2006
Posts: 172
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From: Quakertown, PA
OK, more info...
C1 connector (GM designation) (light grey color) contains the starter solenoid wire, position C10, purple with white trace. Connect this to the wire that went to your old starter solenoid. Also, A9, pink, is switched ignition return from the ignition switch. Connect this to the circuit that used to power the ignition coil.
C2 connector (engine harness, black), I left as is. I am keeping all of the emissions controls...
C3 connector( Lighting, red). F1, grey, is the fuel pump switched power. Connect directly to the fuel pump.
C4 connector (lighting, green). I am not using it, but it does contain one wire for the stock AC system.
C5, black. Not used.
C6, brown. There are two wires coming from this connector, both red 10ga. They are both fused by the maxifuses. I used one as 12V supply to the ignition switch. They are alway hot.
C7 & C8, not used.
Please note, I have not actually had my motor running yet. The starter circuit is a definite, since I have turned the motor over with the key. My fuel system is awaiting one part before I try to start it. I will report back once I get to that point.
C1 connector (GM designation) (light grey color) contains the starter solenoid wire, position C10, purple with white trace. Connect this to the wire that went to your old starter solenoid. Also, A9, pink, is switched ignition return from the ignition switch. Connect this to the circuit that used to power the ignition coil.
C2 connector (engine harness, black), I left as is. I am keeping all of the emissions controls...
C3 connector( Lighting, red). F1, grey, is the fuel pump switched power. Connect directly to the fuel pump.
C4 connector (lighting, green). I am not using it, but it does contain one wire for the stock AC system.
C5, black. Not used.
C6, brown. There are two wires coming from this connector, both red 10ga. They are both fused by the maxifuses. I used one as 12V supply to the ignition switch. They are alway hot.
C7 & C8, not used.
Please note, I have not actually had my motor running yet. The starter circuit is a definite, since I have turned the motor over with the key. My fuel system is awaiting one part before I try to start it. I will report back once I get to that point.
I have like 6 wiring harnesses from 2004 and 2005 6.0 trucks I took off trucks at work.These trucks are oil field used so all that jumping around breaks the wires of the tac module.So we basically just swap entire harnesses I get to keep them since they have no warranty because of mileage.They all have that big connector that bolts to the outside fuse box.
On The Tree
Joined: Jan 2006
Posts: 172
Likes: 0
From: Quakertown, PA
Found a mistake, sort of. Power for the transmission, and the fourth power circuit for the PCM, is not fused or powered through the under hood fuse block. In stock form it is fused through the in cab fuse block. The transmission will not shift as a result. The fix is simple though. Fuse #21 is not used, but is in place and intact. The power wire for the trans needs to be moved from its current location to a different hole in the same connector. I will post the details once I confirm this.
Last edited by jeepinpete; Mar 14, 2007 at 02:53 PM.
