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Old 12-23-2020, 01:29 PM   #1
BIGglaSS
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Lets get this LS 5.3 running!

I have been researching LS swaps for several years. I forget more than I remember, and waste countless hours looking for information. Since there seems to be no exact recipe, and every swap situation is slightly different, I'd like to start a thread dedicated to getting my truck running. I don't intend this thread to be "I'm too lazy to search". Simply a place to ask for advice or solve problems as they arise.

The truck: 1957.


The donor: 2004 5.3 flex fuel, 4L60e, hacked factory harness.


Some of the specifics:
- A/C
- Dakota Digital BIM
- Add cruise control
- Volvo 2 speed 16" fan



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Old 12-23-2020, 01:42 PM   #2
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Re: Lets get this LS 5.3 running!

The last couple days were spent sorting out this mess:



The guy I bought the donor from, already started pulling pins and cutting wires. For the most part, I have it sorted out, and it makes sense. I have been following the LT1swap site to sort this out. However, a few questions.

The box on the shift selector has a broken terminal, and both of these plugs/wires were removed from the PCM. Do I need these?


The oil pan sensor was removed from the harness. As far as I understand, it is not needed. Should I add it back anyway, as a feature for the Dakota Digital dash to read?


Do local auto parts stores typically have replacement PCM pins?

I have no wiring to hook up the gas pedal to the TAC module. I assume it is one cable that runs between the two. Is this something I will have to find in a junkyard?

The rear O2 sensors were removed from the harness (which I still have). I will be running catalytic converters. Do I have to add them back into the harness?

Thanks
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Old 12-23-2020, 01:54 PM   #3
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Re: Lets get this LS 5.3 running!

You will need a new transmission range switch. People break them all the time, the factory uses a sealant almost like a glue on them to keep them weather tight. A little time with a heat gun and they come apart super nice, if there's a pick a part near might try that vs a new one. If you want your EMC to control the trans I'm pretty sure you need those two connectors as well as the main valve body harness on the other side. Doubtful a parts store will have ECM pins, that's an online thing or the junk yard, or dealer. The oil level sensor I would leave deleted. The rear o2's, even with cats do nothing for fuel trims, they are souly there to keep tabs on the converters, you can add them if you want, but not necessary for operation.
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Old 12-23-2020, 03:16 PM   #4
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Re: Lets get this LS 5.3 running!

Thank you! If I get motivated, I will go look for a new gear selector.

I just found other issues with the harness. I'm leaning toward buying a new one, since I have to add things back that were removed, and I don't want to chase down gremlins in the future. Note to self... don't buy other peoples abandoned problems/projects. Argument for new harness.

Rear o2 harnesses were wound up in a box, kinked, chafed, etc. If I add them back, I don't want wire issues. Another argument for new harness.

Found a couple wires near the PCM that are damaged. Another argument for new harness.

Next, These sensors on the back of the engine:
I assume the round white one is Oil Pressure. Yet oil pressure was removed from the harness. I found the pins where I believe the black and grey wires should go, but not the red/black wire. Another argument for new harness.



I just discovered that the MAP sensor is missing, and one of the tabs is broken.
Is there a fix for the missing tab?


Did I just talk myself into buying a new harness?
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Old 12-23-2020, 04:10 PM   #5
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Re: Lets get this LS 5.3 running!

Are you leaving DOD in this motor? Map sensor you can put a brass nipple in the hole with the right size hose end on it and run a line to your map sensor, or if you're not running boost it will possibly be ok with one tab, or score another truck intake. Sounds like you talked yourself into a new harness. I see un touched ones pop up on FB and ls swap pages for 150 or less, or again if you have a you pull it yard, you've got a nice little shopping list going.
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Old 12-23-2020, 04:36 PM   #6
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Re: Lets get this LS 5.3 running!

Uh, DOD? I didn't think this engine had it.

Had I noticed the broken tab, I would have bought another intake before installing this one.
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Old 12-23-2020, 05:50 PM   #7
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Re: Lets get this LS 5.3 running!

I would buy a new harness. It's no fun chasing electrical problems. I've never used a reworked stock harness. I like Howell and Speartech harnesses. They can also reprogram the stock ECM.
I've never used the trans position sensor attached to the shift lever. I have used the shifter neutral safety switch on my LS/4L60E swaps.
You do need to use valve body wires and the VSS wires.
I would get a new intake. Truck intakes are cheap. If the engine has been sitting for some time I would pull the injectors and have them cleaned.
Oil level sensor in the oil pan is not needed. I replace the stock one with an aftermarket plug.
The stock oil pressure switch is at the back of the block as in your pic. The cam sensor is next to it.
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Old 12-23-2020, 06:07 PM   #8
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Re: Lets get this LS 5.3 running!

Most harnesses delete the oil pressure switch. So don't worry about that one. That single tab should be fine for the map sensor but like biketopia said you can plug it into another vacuum hose (its what I did).

Side note, replace all your sensors while you have it apart. Its cheap insurance. I just spent two days with an no start issue because of a bad crank position sensor that didnt throw a code right away.
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Old 12-23-2020, 06:34 PM   #9
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Re: Lets get this LS 5.3 running!

Subbed for info!
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Old 12-23-2020, 06:41 PM   #10
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Re: Lets get this LS 5.3 running!

I'm just going to add my $0.02 in here and it's maybe different from others, so take that as you may.

If you are comfortable with wiring, you should be able to fix the harness, but if not, buy a new one. It sounds like you just want confirmation that a new harness is the way to go. It's your call and your money and truck.

That said, I'll try to answer the other questions to the best of my ability.

The transmission range sensor isn't absolutely needed, but does have features that are nice to have. Engine will run and transmission will shift fine without it, but there are wires that go to the PCM in it that give it info it won't get anywhere else. If you need to do a "crank relearn" for example, without it hooked up, it won't be possible. You could also use it as a neutral safety switch and back up light switch if you feel so inclined. Note however, if you buy an aftermarket harness, it most likely won't have the wires for it.

The oil level sensor is something everyone deletes. I really doubt the DD will be able to use it as it doesn't go to the PCM, and the oil has to be real low for it to trip, something any car guy would never let happen anyway!

Rear O2's will be fine to remove even if you are using cats. They just tell the PCM if the cats are working to spec, but they don't change anything. If you use anything but the factory cats they could be different enough that they could be working but the sensors could possibly tell the PCM that they aren't working up to spec and turn the check engine light on anyway. Personally, I would leave them off. Also, if you get a new harness, these won't come as standard equipment, so you will have to request that they add them.

Oil pressure sensor isn't needed either, and is another sensor that doesn't go to the PCM, so again, the DD won't be able to get a reading from it. You will have to install the DD sender in the engine to get that reading.

A 2004 won't have displacement on demand (DOD), that's a GenIV engine thing, you have a GenIII.

The MAP sensor will be held in by the black plastic part that bolts on with 3 bolts that the Vortec cover hooks on to, so if you're running the cover, that should be all you need.

You will definitely need the jumper harness between the TAC and pedal. Junk yard is a good source for them, or if you don't have one near, hit me up, I have a lot of that stuff lying around.

I think I got them all? There's a lot going on in this thread already!!
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Old 12-23-2020, 08:01 PM   #11
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Re: Lets get this LS 5.3 running!

Cool, cool, cool. Super helpful.

ls1nova71, gave me a good idea to fabricate a bracket to hold the sensor in. easy.

TAC - pedal harness, I will get from junkyard.

Shift selector, use what I got, and seal with silicone. If it doesn't work find one at the junkyard.

Oil pressure switch, if I figure out where to put the red/black wire, I'll use it. Otherwise delete.

Oil level sensor, delete.

Rear o2's, leave them out.

Quote:
You could also use it as a neutral safety switch and back up light switch if you feel so inclined. Note however, if you buy an aftermarket harness, it most likely won't have the wires for it.
Do you mean the new harness would not have neutral safety switch & back up light? Or do you mean that a new harness does not plug into the shift selector module? Which brings up a good point. I never thought of back up light or NSS. Just assumed the PCM would have control of NSS.

So, new harness vs what I got. I think will come down to whether or not I can re-attach the shift selector plugs back into the harness.

Does anyone know of any cool small fuse/relay boxes that are easily found at a junkyard? Enough to run the LS harness, fans, and fuel pump?

I also have to decide where to mount the TAC and PCM. There's plenty of room on the inner fender, or try to hide under the dash. I don't think it will reach to under the seat.
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Old 12-23-2020, 09:10 PM   #12
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Re: Lets get this LS 5.3 running!

Quote:
Originally Posted by biketopia View Post
Are you leaving DOD in this motor?....
Quote:
Originally Posted by BIGglaSS View Post
Uh, DOD? I didn't think this engine had it....
Biketopia is seeing the flat connector beside the oil pressure sensor. On the gen-3 engines, this is the cam sensor. On gen-4 engines, the AFM solenoid connector is in the same location, and looks very similar. The confusion is understandable.

The best way to identify the gen-3/gen-4 difference when looking at that part of the engine -- the gen-3 oil sensor screws into the block, while the gen-4 oil sensor screws into the valley pan cover.

The gen-4 engines moved the cam sensor to the timing cover.
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Old 12-24-2020, 07:41 AM   #13
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Re: Lets get this LS 5.3 running!

Quote:
Originally Posted by kipps View Post
Biketopia is seeing the flat connector beside the oil pressure sensor. On the gen-3 engines, this is the cam sensor. On gen-4 engines, the AFM solenoid connector is in the same location, and looks very similar. The confusion is understandable.

The best way to identify the gen-3/gen-4 difference when looking at that part of the engine -- the gen-3 oil sensor screws into the block, while the gen-4 oil sensor screws into the valley pan cover.

The gen-4 engines moved the cam sensor to the timing cover.
Yup you got me! I quickly glanced at the pictures and moved right past it, I deal with a bunch of gen 4 stuff at work so forget about the subtle differences on the gen 3 stuff.

But OP, seems like everyone has got you steered in the right direction, I also learned a thing or two with the range selector switch not being needed.
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Old 12-24-2020, 04:26 PM   #14
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Re: Lets get this LS 5.3 running!

Does the oil pressure switch read actual PSI or on/off?

I can't figure out where the red/black wire goes. All diagrams online show the third wire as tan/white (not red/black), which might be pin 58 on the green block (58 TAN/WHT 332 Oil Pressure Sensor Signal)? it appears there used to be a pin in that location.

I'd like to add it back in if it will give oil pressure data to the gauge cluster. That's where I'm going to stick it unless someone tells me otherwise.

link to diagram: http://www.lt1swap.com/pictures/03to...e%20Sensor.gif
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Old 12-24-2020, 05:32 PM   #15
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Re: Lets get this LS 5.3 running!

I have nothing to add, other than looking good neighbor
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Old 12-24-2020, 07:04 PM   #16
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Re: Lets get this LS 5.3 running!

Quote:
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I have nothing to add, other than looking good neighbor


Hey guys, disregard the last post about the oil pressure sensor. I had the wrong pigtail. Found the correct one with the right colors! Re-installed.

Also, I got the shift range harness put back in.

However, all the wires were cut from the neutral safety switch pigtail. From the best I can tell, do any of these go to the PCM?

Thanks, and Happy Holidays!
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Old 12-24-2020, 09:43 PM   #17
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Re: Lets get this LS 5.3 running!

There are several wires that go to the PCM from the transmission mounted NSS, but they are not the actual neutral safety portion of it, you would have to add a relay for it.
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Old 12-26-2020, 04:52 PM   #18
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Re: Lets get this LS 5.3 running!

You don't HAVE to use the neutral safety switch on the transmission. You can use one on the column or on a floor shifter. It just has to interrupt the 12v START wire that you have to connect at your harness connections. I wanted a floor shifter so I went with one that had both nss and back up switches.
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Old 12-27-2020, 02:38 PM   #19
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Re: Lets get this LS 5.3 running!

which volvo does that fan come out of?
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Old 12-27-2020, 02:56 PM   #20
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Re: Lets get this LS 5.3 running!

Fixing that harness wouldn't be difficult.
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Old 12-27-2020, 08:28 PM   #21
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Re: Lets get this LS 5.3 running!

Quote:
Originally Posted by ls1nova71 View Post
There are several wires that go to the PCM from the transmission mounted NSS, but they are not the actual neutral safety portion of it, you would have to add a relay for it.
I think I have it all sorted out from following this thread (which you also gave advice)
https://ls1tech.com/forums/conversio...in-outs-2.html

Question: Isn't the starter solenoid a relay? Can I go directly from the NSS to the starter solenoid, or do I have to add an additional relay between them? Kind of redundant to use a relay to fire a solenoid... The AAW harness instructions have the NSS direct to starter.

I spent the last couple days laying out the AAW harness, along with the engine harness, and trying to plan how to integrate the two. For the most part, I have it all planned out. Trying to keep it clean and tidy. I'm sure I'll have more questions as the come up. Taking a break for a couple weeks, I'll report back as I move along.

Quote:
which volvo does that fan come out of?
I don't exactly remember what model it comes from. Following this tutorial. I hope it gets the job done!
https://www.therangerstation.com/tec...tric_fan.shtml
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Old 12-27-2020, 09:04 PM   #22
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Re: Lets get this LS 5.3 running!

You will need a relay to use the transmission mounted NSS as the wiring in it is way to small to carry the load to the starter solenoid. If you are using an older column mounted NSS then you don't need the relay because they're made to handle the load. Just look at the wires on each one, you'll easily see the difference.
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Old 12-27-2020, 09:06 PM   #23
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Re: Lets get this LS 5.3 running!

i think the answer to your question is that you can't go directly with the high current through the neutral safety switch or else you'll roast it. It won't handle it. Hence the relay.
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Old 12-28-2020, 05:30 PM   #24
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Re: Lets get this LS 5.3 running!

you are baslicyy useing the 12 volt in and 12 volt out of nss to tigger a relay that handles the current of the starter solnoid. and no the solenoid is not a a relay it is a giant magent that moves an arm to engage the starter and starter bendix which just the hot singal wire can pull up to 20-40 amps plenty to smoke the transmission mounted nss
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Old 12-31-2020, 02:15 PM   #25
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Re: Lets get this LS 5.3 running!

I have a 'parts harness' just like yours....if you need PCM connector round pin receptacles, let me know. Message me the wire colors you want, if I have them I'll pull out and cut as much wire back as I can. You can then splice into yours.
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