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5.3L Swap Underway.... Goodbye 2.5L Squirrel Power

4K views 57 replies 17 participants last post by  Jeepfreak81 
#1 ·
Started my swap this past weekend, out with the old in with new.
 

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#5 ·
EABiker said:
That is one clean YJ! What was the donor vehicle?
That's also one clean engine, is it a gen IV?
 
#9 ·
Yeah Counselor Troi is my therapist when crap doesn't go like it should, that why she keeps hanging around the Jeep. :wink2:

My donor was a 2003 GMC Yukon XL with 96,000 miles (well that's what they claimed) got the complete motor, wiring, PCM, and transmission. I pulled the oil pan and valve covers off and it's very clean. I think I have some pictures I will post them if I can find them. I also ran a compression check and all cylinders checked good.

Yes, I am going to swap the rear end. I got a 4.10 LS from a 2002 Ford Explorer that had 106,000 miles on it. For now I am going to keep the stock front end.

My wiring I did myself. Brendan from LT1swap.com lays it out pretty straight forward, he is also doing the reprogramming of my PCM.
 

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#15 ·
I got my wiring info from lt1swap.com and bought a manual from eBay.

Brendan has a great site with tons of information on it. He breaks it down into easy steps so even a beginner can do it, it just takes time. He also has a Facebook site with plenty of pictures showing the step by step process.

The manual I bought on eBay had a lot of good info, but in essence it was a waste of money. :mad:

It took me a couple of weeks doing a few hours here and there to complete it. Brendan's site has all the info you need to do your wiring, also he does PCM programming for $75. I should be getting it back next week.:smile2:
 
#14 ·
Okay Guys, I need some help. I’ve searched numerous threads but never found a straight forward way integrate my 5.3 wiring to the stock Jeep wiring.

I have the 5.3 wiring completed, so in theory I should be able to run the motor and transmission if I had the PCM hooked up. Which I should get it back next week sometime.

Well I’m trying to keeping all my stock gauges, speed, tach, oil pressure, coolant temp, and voltage. But I’m having issues trying to rap my head around it. :confused:

My problem is the manual states that the VSS receives 8 volts from the PCM on circuit K7, so if I remove Jeep PCM my gauge won’t work, then there is the Tach…….? I already started stripping the old PCM and Jeep wiring, but I guess I can put it back in.

I was also thinking of keeping the Jeep power distribution panel and running the 5.3 from it (so it keeps the stock look).

Any help would be appreciated.
 

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#16 ·
Okay Guys, I need some help. I've searched numerous threads but never found a straight forward way integrate my 5.3 wiring to the stock Jeep wiring.
Here are a few pointers from when I did my GM into Jeep swap...

  1. I subscribed to AllDataDIY.com for both the doner vehicle and Jeep year, so I could see "Jeep red with white stripe connects to GM blue with green stripe", etc..
  2. I eliminated completely the YJ under hood fuse box, only used the GM. The YJ block mainly had high amp body things that needed to be moved, and there are plenty of unused high amp fuses in the donor fuse box (power seats, HVAC, etc.).
  3. I had to have the GM PCM flashed to eliminate the VATS and most any other code that deals with things not on the YJ, like fuel tank pressure, after cat O2 sensors. I told them, "Just leave working whatever it takes to make the motor run right."
  4. I used a Dakota Digital SGI box to send the VSS signal to the GM PCM, which likes to know if the vehicle is moving or not.
  5. You might need another SGI box to get the V8 GM tach signal to work right with a I4 YJ tach. I did until I changed to Autometer gauges
 
#17 ·
Thanks for the reply JeeperDon.

Here are a few pointers from when I did my GM into Jeep swap...
I subscribed to AllDataDIY.com for both the doner vehicle and Jeep year, so I could see "Jeep red with white stripe connects to GM blue with green stripe", etc..


I have the Mopar factory shop manuals for my Jeep, that is where I am getting my info on the wiring. As for my donor it was a drop out (engine, transmission, PCM, TAC, wiring harness, gas pedal, and fuse block) didn't have the complete vehicle. I got the wiring info form lt1swap.com to assist in making the wiring harness.

I eliminated completely the YJ under hood fuse box, only used the GM. The YJ block mainly had high amp body things that needed to be moved, and there are plenty of unused high amp fuses in the donor fuse box (power seats, HVAC, etc.).
Yeah, didn't think of doing that.


I trashed the fuse block when I completed my wiring project. On my wiring harness I have a small fuse block with a fuel and starter relay. But then as I was taking the Jeep fuse block off I started thinking of keeping it and integrate into the new motor wiring.

I had to have the GM PCM flashed to eliminate the VATS and most any other code that deals with things not on the YJ, like fuel tank pressure, after cat O2 sensors. I told them, "Just leave working whatever it takes to make the motor run right."

My PCM is getting programmed as we speak, should get it back next week. He is removing all the emissions junk, VATS everything except what is need to run the engine.

I used a Dakota Digital SGI box to send the VSS signal to the GM PCM, which likes to know if the vehicle is moving or not.

I'm using the Advanced Adapters Trans to TC adapter that has the 40 pulse VSS sensor to run the PCM.

You might need another SGI box to get the V8 GM tach signal to work right with a I4 YJ tach. I did until I changed to Autometer gauges

I may need to look in to that if I'm going to try to keep my stock gauges. I looked into re-gauging my Jeep in the beginning, but wanted to stay as stock looking as I can keep it. I may have to end up doing it anyway if there isn't a viable way of getting the gauges to work with the new setup.
 
#18 ·
I looked into re-gauging my Jeep in the beginning, but wanted to stay as stock looking as I can keep it.
Keep it stock... says the guy swapping in the GM motor...:laugh2:.

I figured with a GM motor and a Ford axle in back, I might as well go CJ'ish for the dash. This is what I have with all Autometer. Panel was made for me in 2010 by Dan Dilner at DoubleDFab

 
#20 ·
There are different ways to go about the wiring. The easiest would have been to keep your YJ fuse block (PDC) and run the circuits for the new motor in place of the old stuff.

With my Jeep being older, it didn't have an OE PDC under the hood so after running some ghetto wiring for a while, I built my own. I paid to have my harness done so most of my engine functions (O2 sensors, injectors, coils etc.) are run through their own small fuse panel that came with it.

Other functions like Torque Converter, crank, fuel pump etc. are run through the new PDC.

Here is where my re-wire project was in my build http://www.jeepforum.com/forum/f22/yj-5-3-build-without-clever-name-1484933/index140.html
 
#21 ·
There are different ways to go about the wiring. The easiest would have been to keep your YJ fuse block (PDC) and run the circuits for the new motor in place of the old stuff.
Thanks Randon, nice build page or pages........

Yeah I'm thinking that I will keep my Jeep PCM and power distribution. I just need to figure out what needs to stay and what needs to go. You have a few links in you post that had others do the same thing with good results. I just need to read a little more, I did noticed that they were TJ's but I think they should be similar.

There is still hope for my gauges.:D
 
#22 ·
You shouldn't need to keep your Jeep PCM for anything. You should be able to run all of your gauges without it.

Fuel will stay the same as long as you retain the factory circuit.

Oil pressure can be adapted to the new motor.

Coolant temp can be adapted to the new motor.

Voltage can be kept from stock wiring

Speedo will be supplied via your adapter/vss

Tach is the only iffy one, and the only gauge that doesn't function in my Jeep. I've heard that there are ways of making the 4 cyl tach work with the GM signal
 
#23 ·
Okay, I was thinking that I would need to keep the Jeep PCM only because of the supply voltage needed to run the vehicle speed sensor in the transfer case. The VSS that is in my transmission to T/C adapter was going to supply just the vehicle speed to the GM PCM.

JeeperDon mentioned about using a Dakota Digital interface for both his speedo and tach. I was only going to use a D.D. interface for the tach from the GM PCM and the speedo signal from the Jeep PCM. Doing this would save me $80, and I think my wife wouldn't appreciate me getting her two D.D. interfaces for Christmas. :grin2:

Will the VSS on the T/C adapter work with the stock Jeep speedo without an signal interface? Maybe I need do the same that JeeperDon did.

The fuel, temp, and oil would use the stock wiring from the jeep, this part looks pretty straight forward, I think.......
 
#24 ·
I had a brain fart when I typed that. You are correct, the AA VSS will supply the 5.3 PCM with a speed signal but the VSS in your current transfer case will continue to send the signal to your speedometer.

That is the only real incentive to keep the Jeep 231. Otherwise is would be cheaper to grab a 241c.

Sent from my LG-H910 using Tapatalk
 
#26 ·
Well here is a mod I did to my temp switch being the stock Jeep switch wouldn’t fit the 5.3.

I had an adapter that fit the 5.3 head, but the temp switch wouldn’t fit all the way into the coolant flow. So, I thought hmmm…… I’ll cut the threads off the adapter and solder it to the T/S…….. I’ve soldered numerous water pipes and A/C refrigerant lines and the all held, so why couldn’t I do this……. :|

Here’s what I did. First I ground off the threads off the T/C, then I cut the threads off the adapter. I fit the new threads on to the T/S using my Drumel tool. After I was satisfied with the fit I soldered them together, it came out fine.

I then installed it into the head of the 5.3, it fit perfect…….. :smile2:
 

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#27 ·
Got most of the wiring done. I decided to go with JeeperDon's suggestion and use two Dakota Digital units for the speedo and tach, I'll get them ordered from Summit Racing this week.

I also thought about using a step down transformer from 12v to 8v to run the stock speed sensor in the T/C. In theory it should work, but being I’m not 100% sure that it would, I’m not going to chance it and waste $50.
 

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