TJ forum inspired 4-cylinder to V8 Magnum build

PirataCoqui

TJ Enthusiast
Supporting Member
Joined
Nov 4, 2021
Messages
112
Location
Raleigh NC
I was inspired to start this build by this forum after countless hours of reading and forming my own opinion. My initial intent was going with an LS but I just couldn’t convince myself that is the route I needed to go.

My intent behind this thread is document some design decisions, mistakes, and nuggets of information I have found useful during my journey.

As starting point it’s 2001 Tj with 4cyl engine, automatic with 3.73.

It’s painfully slow, or was.
Progress to date: sold original engine, transmission and exhaust.

Initial decisions summary:
Goal is to get it running safety and cost are a constraint in my decisions, but I also don’t like to redo work.

- decided my donor will be a well maintained 2001 Dodge Ram 5.9 automatic.
-will try to run original tj radiator with original and let temperatures dictate any upgrades
-will use advance adapters engine mounts in suggested location
-will use jb conversions super short sye
-I don’t want to regear
-I want to add ac and cruise control but not at the expense of extending the engine swap downtime.
-I don’t care about it looking stock, but I want it to look good to me.
-I am not going to replace or overhaul any major parts of engine or transmission until I have to.
-I am going to install Savvy body lift as part of the process


Decision Realities( ie what I had to rethink(updated2/23/2023)
-2001 Dodge ram is ccd vs my 01 tj’s pci. So I had to buy a pci 5.9 auto pcm
-I under estimated the rust I had to address. I had to spend a month doing rust repair.
-I replaced the side body mounts with genright body mounts since they where in poor shape
-rear( bumper) tub mounts where rusted off. I didn’t want to cut up my whole rear so I welded pieces of square stock on each side to the tub and reinforced with bolts. (It’s invisible to anyone but me).
-I had Dana 44 in my future plans and decided I rather not buy another driveshaft in the future. So I bought a rear LJ Dana 44 with disc brakes, 3,73 gears.

More pics to come soon…

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Welcome to the Magnum V-8 swap world.

What size tire are you planning on running once the swap is all done? 3.73 gears could work with 33" or smaller but anything larger & IMO you'll need to regear.
Which transmission are you planning on using? The 46RE from the truck or a manual?
How many miles are on the truck? Even a well maintained rig will develop leaks. I would consider replacing seals and such while you have the engine pulled as it's a lot easier to work on out of the Jeep than in it.
You should definitely do the Plenum gasket if it hasn't already been done.
Are you building your own wiring harness? @RangerRick added cruise control to his TJ when he did his swap so it can be done.
While you are sourcing parts you might want to get a Jeep Grand Cherokee power steering bracket & pump as it makes it sit tighter to the block then the Ram mount.
As far as using your stock radiator I know guys who did it with the 5.2 but I don't think anyone did with the 5.9. The 5.9 runs hotter than the 5.2. You have to run a combination of hoses & pipe to get the bottom hooked up. The top isn't as hard but if you're wanting to add A/C then the hose location can come into play.
I've got a lot of information on the magnum engines & some cheat sheets for the wiring if you are interested.
 
Thanks for the tag @Wildman as part of the Magnum TJ club and having done two TJ Magnum V8 conversions, I have some insight that the OP might want to know up front.

First I highly recommend you find a 5.9ZJ Grand 46RE for the transmission for driveshaft clearance unless you are going to have enough lift in the suspension otherwise things can get tight. It's not to say you can't use the RAM 46RE but I would find a ZJ 46RE if you can possibly swing it. You CAN use a 44RE from a 5.2L BUT it is not nearly as strong in the front hub and pump section plus, it doesn't have as beefy clutch packs in it. If you are going to tow anything or do serious mud wheeling you're better off with the 46RE. Pay the piper NOW rather than rebuild several times down the trail later. Now if this is going to be a street queen mall-crawler and you're not going to do parking lot brodies for your buddies to YouTube, then the 44RE will be fine on a STOCK BUILD LEVEL 5.2/5.9L engine. Any significant build for power then then go straight for the 46RE.

Note flex plates are different because of internal vs. external engine balance on the different displacement Magnum V8's. Keep that in mind if you are swapping out transmissions from different engines.

If you are a rock crawler, the Ruby-Crawler extension box will work with these automatics. You can use one of them instead of a 4:1 transfer case conversion or the Atlas II conversion. If you like dunes and mud, stick with the stock transfer case ratio for wheel speed.

Easy to use motor mounts with the correct placement position indexed on the TJ frame can be had from AA, (Advanced Adapters) directly on their website. Just search Magnum TJ motor mounts to find them.

Use the factory "Y" pipe head pipes, O2 sensor bungs to the cat straight of a ZJ Grand 5.2 or 5.9 with the exception that I would cut out the pinched section on the passenger side branch and replace it with regular pipe to get rid of the small "restriction" it creates. I used the CAT back from both TJ's we converted. The exhaust literally looked like factory and passed emissions inspections right out of the gate because they were factory Jeep parts. On a ZJ, the head pipe is already cut and routed for the transmission and oil pan so it tucks up nicely and fits like a glove in the TJ Wrangler. Another reason I like using a ZJ for donor parts.

I am not sure how the RAM "Y" pipe will fit as some say there is interference on the drivers side of the front drive shaft with the starter from a RAM drivers side transmission. On ZJ's the starter is on the passenger side just like in the TJ Wrangler so no interference of the exhaust or to the drive shaft.

If you are a good critical thinker and can read a schematic/service manual AND understand it, build the wiring harness yourself. The beauty of the Magnums and the 2.5L TJ is for the most part, the ECM's have the same pin out configuration in the connectors depending on BUS architecture and actual year model.

Yes cruise control is not difficult to add and if you build the harness and do the swap nicely, you can make it look like your TJ came with the 5.2/5.9L Magnum from the factory.

Exhaust manifolds used on the ZJ platform will work great and don't cause lots of cab heat issues. Headers are another issue altogether and I defer to those who run headers for their take on them. I prefer stock manifolds myself in the conversion for space and emissions compliance reasons. Remember, I reside behind the iron curtain in the PRK where everything freedom is frowned upon.

Don't forget about wonderful SKIM security issues and I see you (the OP) have already found out about ECM/ECU BUS architecture. It's always best to use like architecture donors (if and where possible).

While we are on the subject of BUS architecture, some ECM's will not properly run the TJ dash. Example is a 1997 RAM will not run the dash in a 1998-1999 TJ. I had to find a 1998 RAM ECM for that to work. Remember the ECM controls the gauges in the TJ and 1998+ RAM trucks. This is just ONE example of things I found that weren't posted anywhere on the web when I did the conversions on two TJ's back-to-back.

I have used a stock radiator to cool the 5.2L but as @Wildman suggests, if you aren't using a factory 4.0L fan shroud and a mechanical fan, you will most likely have overheating problems on hot or high load days, especially if you don't properly re-gear for tire size. Remember the factory radiator also has a built in trans cooler and a transmission working harder because of the wrong axle ratio for the tire size creates more heat in the fluid which has to be dumped somewhere, in this case the radiator. I ran an external transmission cooler "stacked plate" type taken from a ZJ Grand with tow package as a secondary add-on transmission cooler AFTER the internal radiator trans cooler to help extend fluid and transmission life. It fits on the black support tube strut in front of the A/C condenser in the grill of a TJ like it was made for it.

***Best cooling system advice I can give you is run ZJ Grand accessory belt and brackets with the ZJ power steering pump and use the Jeep thermal mechanical fan and 4.0L radiator factory fan shroud. NO ELECTRIC FAN B.S. if you want your absolute best cooling and reliability in a Magnum swap.

Yes, absolutely run a ZJ Grand accessory belt system with the power steering pump and brackets to save a huge amount of room under the hood on the driver side fender area. It will connect to your 1996.5-2002 TJ power steering system without any adapters whatsoever.

Pre-emptively do the intake plenum gasket for sure before installing the V8 or you will regret having to do it in the TJ. 99% of them are leaking by now and need replacement as you're talking 25 years old plus!

If you have questions you can always ask me, I'll be happy to answer them if I can, there's a ton more that hasn't been mentioned.



RR
 
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Thanks for the tag @Wildman as part of the Magnum TJ club and having done two TJ Magnum V8 conversions, I have some insight that the OP might want to know up front.

First I highly recommend you find a 5.9ZJ Grand 46RE for the transmission for driveshaft clearance unless you are going to have enough lift in the suspension otherwise things can get tight. It's not to say you can't use the RAM 46RE but I would find a ZJ 46RE if you can possibly swing it. You CAN use a 44RE from a 5.2L BUT it is not nearly as strong in the front hub and pump section plus, it doesn't have as beefy clutch packs in it. If you are going to tow anything or do serious mud wheeling you're better off with the 46RE. Pay the piper NOW rather than rebuild several times down the trail later. Now if this is going to be a street queen mall-crawler and you're not going to do parking lot brodies for your buddies to YouTube, then the 44RE will be fine on a STOCK BUILD LEVEL 5.2/5.9L engine. Any significant build for power then then go straight for the 46RE.

Note flex plates are different because of internal vs. external engine balance on the different displacement Magnum V8's. Keep that in mind if you are swapping out transmissions from different engines.

If you are a rock crawler, the Ruby-Crawler extension box will work with these automatics. You can use one of them instead of a 4:1 transfer case conversion or the Atlas II conversion. If you like dunes and mud, stick with the stock transfer case ratio for wheel speed.

Easy to use motor mounts with the correct placement position indexed on the TJ frame can be had from AA, (Advanced Adapters) directly on their website. Just search Magnum TJ motor mounts to find them.

Use the factory "Y" pipe head pipes, O2 sensor bungs to the cat straight of a ZJ Grand 5.2 or 5.9 with the exception that I would cut out the pinched section on the passenger side branch and replace it with regular pipe to get rid of the small "restriction" it creates. I used the CAT back from both TJ's we converted. The exhaust literally looked like factory and passed emissions inspections right out of the gate because they were factory Jeep parts. On a ZJ, the head pipe is already cut and routed for the transmission and oil pan so it tucks up nicely and fits like a glove in the TJ Wrangler. Another reason I like using a ZJ for donor parts.

I am not sure how the RAM "Y" pipe will fit as some say there is interference on the drivers side of the front drive shaft with the starter from a RAM drivers side transmission. On ZJ's the starter is on the passenger side just like in the TJ Wrangler so no interference of the exhaust or to the drive shaft.

If you are a good critical thinker and can read a schematic/service manual AND understand it, build the wiring harness yourself. The beauty of the Magnums and the 2.5L TJ is for the most part, the ECM's have the same pin out configuration in the connectors depending on BUS architecture and actual year model.

Yes cruise control is not difficult to add and if you build the harness and do the swap nicely, you can make it look like your TJ came with the 5.2/5.9L Magnum from the factory.

Exhaust manifolds used on the ZJ platform will work great and don't cause lots of cab heat issues. Headers are another issue altogether and I defer to those who run headers for their take on them. I prefer stock manifolds myself in the conversion for space and emissions compliance reasons. Remember, I reside behind the iron curtain in the PRK where everything freedom is frowned upon.

Don't forget about wonderful SKIM security issues and I see you (the OP) have already found out about ECM/ECU BUS architecture. It's always best to use like architecture donors (if and where possible).

While we are on the subject of BUS architecture, some ECM's will not properly run the TJ dash. Example is a 1997 RAM will not run the dash in a 1998-1999 TJ. I had to find a 1998 RAM ECM for that to work. Remember the ECM controls the gauges in the TJ and 1998+ RAM trucks. This is just ONE example of things I found that weren't posted anywhere on the web when I did the conversions on two TJ's back-to-back.

I have used a stock radiator to cool the 5.2L but as @Wildman suggests, if you aren't using a factory 4.0L fan shroud and a mechanical fan, you will most likely have overheating problems on hot or high load days, especially if you don't properly re-gear for tire size. Remember the factory radiator also has a built in trans cooler and a transmission working harder because of the wrong axle ratio for the tire size creates more heat in the fluid which has to be dumped somewhere, in this case the radiator. I ran an external transmission cooler "stacked plate" type taken from a ZJ Grand with tow package as a secondary add-on transmission cooler AFTER the internal radiator trans cooler to help extend fluid and transmission life. It fits on the black support tube strut in front of the A/C condenser in the grill of a TJ like it was made for it.

***Best cooling system advice I can give you is run ZJ Grand accessory belt and brackets with the ZJ power steering pump and use the Jeep thermal mechanical fan and 4.0L radiator factory fan shroud. NO ELECTRIC FAN B.S. if you want your absolute best cooling and reliability in a Magnum swap.

Yes, absolutely run a ZJ Grand accessory belt system with the power steering pump and brackets to save a huge amount of room under the hood on the driver side fender area. It will connect to your 1996.5-2002 TJ power steering system without any adapters whatsoever.

Pre-emptively do the intake plenum gasket for sure before installing the V8 or you will regret having to do it in the TJ. 99% of them are leaking by now and need replacement as you're talking 25 years old plus!

If you have questions you can always ask me, I'll be happy to answer them if I can, there's a ton more that hasn't been mentioned.



RR

You've been hiding this information about the RubiCrawler... Heck my driveshaft doesn't have to get any shorter but I get the added 2.72 gearing.

So with the STaK's t-case & 3.05 low & 5.44 low low then throw a RubiCrawler in front it would REALLY crawl.
You're always a great source of information.
Thanks

Edit: Listen to his advice on using a Jeep 46RE transmission over the Ram. My upper control arm is super close to my starter and fitting the exhaust is a major PITA. Now I do have a Savvy midarm kit so it's not a stock shortarm but having the starter on the passenger side would have made life a lot easier.
 
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Confirm with the manufacturer of course to make absolute sure but I believe I have even read a post on another site with guys using it on other transmissions so that intrigued me.

It fits in/replaces the spacer that is the same type as the 42RE/RLE used on the strait 6 4.0 engines. Basically the same transmission rear housing extension as used on the entire family of transmissions is what I read from another Jeep enthusiast forum that got me thinking. Reading it on another website caused me to realize the bellhousing portion and front fluid pump/housing is the basic difference between the 42/44 and the 46RE automatics. The 46RE however has beefier guts in it related closer to the heavier transmissions due to being in bigger vehicles with larger engines. This does open a world of possibilities for some creative gearing and still maintain a drive shaft that isn't 8" long right?

How I managed a rare 46RE from the Grand on the 5.2L conversion I did for one of the Jeeps is I bought a reman from that big on line auto parts store everyone uses with the purple two letter logo.... You guys know the one, and returned the 44RE that came out of the ZJ that was the donor on the first conversion. They wanted a core, wasn't specific it had to be the exact same type so they got a core and the reman was really strong. ZERO issues since they use one of the biggest OEM reman houses in the country to rebuild them on an assembly line.

The second conversion parts donor was a 5.9L Limited ZJ Grand so it had the trans I needed but we still used the same parts store to exchange for a reman unit. Again, not trusting a used trans in a project of this magnitude just to have to yank it again cause it's slipping or toast. too much double labor there.

The transmissions in 2017/2018 prices cost about $2800 each after core exchange. The core was $600 and I had to pay $150 X 2 to return ship each of the cores which kinda sucked. They did send a "coffin" case with the new 46RE's so I put the old ones in them including the old torque converter secured with the metal tab and shipped it back. 3 weeks later, I had a refund of $600 each one on my card that I used to purchase the remans.

The electronics are exactly the same and controlled by the ECM so it plugged right in and worked out of the gate.

I wasn't about to trust a used transmission to the project anyways so it was either rebuild or buy a reman. I chose the latter.....

RR
 
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I have just finished up my 5.9 swap and ran into transmission problems. I took a chance on the 46re transmission with the hopes that just a shift kit would fix the problem it was having. It did for a couple of days but the jeep ZJ 46re was worn out and restricted oil flow internally which lead to things heating up and then melting a sprag clutch cage. I am in the process of rebuilding it right now. When I bought my donner it came with an extra Jeep ZJ 46re thankfully. I have both apart and have used parts from both transmission to make one good complete transmission. Internal parts get expensive fast. Sometimes I wonder if it would not have been easier to go with an AX15 manual trans instead.

The 5.9 was running good when I bought the Grand Cherokee. I did take the advice of others and replaced the plenum, while doing that I also replaced the timing chain. I did not removed the distributor; which on these engines is not for timing of the ignition but for fuel. If you did not know, as that was new to me coming from all Chevy past. I did not remove the heads either as I did not have oil and water interchanging anywhere and it again ran in the proper temp range.

The only thing I might add to all this great advice and plan you have is to measure and consider where you weld in the Advanced Adapter Motor Mounts. If you plan on running a mechanical fan (I did) You may not have room if you put the motor mounts in the suggested location. Others have ran into issues with even electric fans. The options get tight as the space gets smaller. I welded my mounts 2.5 inches AFT or back of their suggestion. I think that you might be able to go back as little as 1.75 inches and have more room in-between motor and radiator for options. That space is critical and cannot gain it back once you weld in the mounts. Since you are planning for a SYE already you will need a different rear drive shaft. One thing to consider is that going 2.5 inches back, I did have to buy a front driveshaft. I felt that if I flexed the front to much the drive shaft would slip apart. I only had about 1 inch of spline engagement on the front stock drive shaft.

Good luck and ask all the questions you run into.
 
Thank you for the advice and comments. Every little bit counts and appreciated.

I have been heads deep in the swap last couple of days. My progress is as follows..

-spot welded the engine mounts and did a test fit ( recommended locations)
-I inspected the plenum gasket with a scope and it looks like it was recently replaced so left as is( hope this doesn’t bite me 👀
-inspected current oil pan, valve cover and checked for oil leaks.
-found a lot of oil accumulated near the distributor/oil sender unit. Can’t tell exactly where it came from but it does seem to originate from the oil sender unit was that is where the oil was the thickest.( replaced with a rock auto. Part number OPS158) easily with this tool(

Lisle 13250 Oil Pressure Switch Socket).​

- hit my first setback… when I lifted the tub for rust repair ( placed it on 6X6 lumber). I tore up my steering shaft bracket and the attachment point on the actual shaft 🤪). So I ordered the skinny steering that I have seen @Wildman talk about. Hopefully I can instal this with the engine mounts in as I have no idea how long it will take to arrive and want to make process.

Answers to a few questions:
-It has a 4in curre lift and 1.25 savvy body lift so I think I will be ok on the starter being on the drives side ( 🤞)
-I have no idea what transmission I have. Need to figure out what it is, but it came out of a 01 ram 4wd 5.9( same as motor)
-I plan on running the transmission cooler I removed from the ram as suggested.
-I bought a 4.0 fan shroud but still don’t know of the ram mechanical fan will work
- I took the repeated advice on the power steering and picked up a remanufactured pump Cardone link

……Have to complete my updates later because ran out of time! Thanks for all the advice
 
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Thank you for the advice and comments. Every little bit counts and appreciated.

I have been heads deep in the swap last couple of days. My progress is as follows..

-spot welded the engine mounts and did a test fit ( recommended locations)
-I inspected the plenum gasket with a scope and it looks like it was recently replaced so left as is( hope this doesn’t bite me 👀

Even if the plenum was replaced recently UNLESS it was replaced with an aftermarket style plenum it will blow again. The best out there is the one offered by Hughes Engines.

https://www.hughesengines.com/Index...U21hbGwgQmxvY2sgRG9kZ2UgTWFnbnVt&partid=30712


-inspected current oil pan, valve cover and checked for oil leaks.
-found a lot of oil accumulated near the distributor/oil sender unit. Can’t tell exactly where it came from but it does seem to originate from the oil sender unit was that is where the oil was the thickest.( replaced with a rock auto. Part number OPS158) easily with this tool(

Lisle 13250 Oil Pressure Switch Socket).​


If it's in the rear like that 90% guess would be that it was a bad job installing the kegger intake after they did the plenum gasket.

- hit my first setback… when I lifted the tub for rust repair ( placed it on 6X6 lumber). I tore up my steering shaft bracket and the attachment point on the actual shaft 🤪). So I ordered the skinny steering that I have seen @Wildman talk about. Hopefully I can instal this with the engine mounts in as I have no idea how long it will take to arrive and want to make process.

Once they got my order and it went thru I don't remember it taking very long for them to get it shipped.

Answers to a few questions:
-It has a 4in curre lift and 1.25 savvy body lift so I think I will be ok on the starter being on the drives side ( 🤞)

The issue can be your control arm can contact it.

-I have no idea what transmission I have. Need to figure out what it is, but it came out of a 01 ram 4wd 5.9( same as motor)

It's a 46RE transmission. It was the only automatic offered in the Ram truck & the only one used behind the 5.9.

-I plan on running the transmission cooler I removed from the ram as suggested.
-I bought a 4.0 fan shroud but still don’t know of the ram mechanical fan will work
- I took the repeated advice on the power steering and picked up a remanufactured pump Cardone link

……Have to complete my updates later because ran out of time! Thanks for all the advice

The Ram fan won't work but if I remember correctly your a 4.0 clutch & fan works but I do remember people using other fans that pulled better air. I'll see if I can find that info.
 
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More updates:
- pictures of it sitting inside ( test fit)
-started on the wiring and am quite annoyed with the service manual. I hate that pin outs pictures are inverted between the ram and tj visually, but for the most part they seem pretty much in line.

I hope to complete my own harness. Spent an hour or so looking over the schematic and walked away with some open items I need to look into.
-my guess is that since I am using the ram harness, I only need to rewire the items that provide go back to the tub vs the pcm.
-not 100 sure how I need to handle the wires that connect to the center on the tj compartment yet. Need to dig into how I integrate that into my harness.

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Here are some wiring cheats. I can't tell you for sure that it's all correct as I haven't gone back and verified every one but I used it to help.

Since you are using the automatic transmission it's easier to use the Ram harness as you said and then blend in the TJ harness where needed.

You will use PCM plugs 1 & 2 from the Ram harness & the TJ plug is PCM #3.

Have you read the Jeep Forum V-8 Magnum swap thread? It's got a lot of good information and tips also.

https://www.jeepforum.com/threads/wrangler-magnum-v8-discussion.1365878/


This thread had some good info too.

https://wranglertjforum.com/threads/questions-on-the-magnum-v8-swap.53411/



If you have a local pull it yard with some older rigs factory 92-93 Dakota manifolds have a larger outlet diameter.

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After reading all the warning on the starter/ control arm/ driveshaft interference I went ahead and did another test fit.

Here are the pictures. This is fully mounted on the motor mounts.
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A picture of my stupidity. Still haven’t gotten a confirmation for my skinny steering. Still says processing. May need to reach out or consider other options to keep the project moving.

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After reading all the warning on the starter/ control arm/ driveshaft interference I went ahead and did another test fit.

Here are the pictures. This is fully mounted on the motor mounts.
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View attachment 404018

The issue some people have had was to have the driveshaft hit the starter at full bump. Of course this happened on rigs with zero lift & no added bumpstop.

Here was mine from my first build. You can just see the end of the starter in this picture.

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And then here is the driveshaft next to the bellhousing.

IMGP0225[1].jpg



Now my upper control arm is very close to the starter because I have the Savvy midarm 3 link/4 link setup.


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For the wiring you are going to use the C1 & C2 plug from the Ram harness & then the C3 plug is for the TJ harness. There are wires you have to splice but I don't have the list in front of me.

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Now my upper control arm is very close to the starter because I have the Savvy midarm 3 link/4 link setup.

Working on my transfer case to see if I can get a test fit with the front driveshaft over the weekend. Started tearing into the ram transfer case as practice. Came apart pretty easy but need better pair of snap ring pliers.
Probably would have saved 30-40 minutes.

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For the wiring you are going to use the C1 & C2 plug from the Ram harness & then the C3 plug is for the TJ harness. There are wires you have to splice but I don't have the list in front of me.

I reviewed the document, some schematics and my take-away as of now are:
  1. C1, C2 stays untouched if I use my Dodge Ram harness with a matching computer.
    • I have a few wires don't line up between my 2001 harness and the 2002 computer I am using.
      • C1 pin 10/11 (idle control valve 3/2) are inverse
      • C1 PIn 19/20(idle control valve 4/1) are inverse
      • C2 pin17 (condenser fan control) is present on 2002, but not on the 2001
      • C2 pin 19(A/C pressure signal) is present on the 2002 but not on the 2001
  2. Differences between C3 on TJ and 2001 Ram harness
    • C3 pin 13 (Overdive off switch base) doesn't exist
    • C3 pin 29((CCD(-) will go unused since my TJ and 2002 are PCI
  3. I need to wire C3 into tj connectors C103 + C104
    • I looked at the wiring schematics for these connectors
      • TJ C103 and C104... I was able to find some of the related circuits but not all. This is where my headache will likely occur.
 
I reviewed the document, some schematics and my take-away as of now are:
  1. C1, C2 stays untouched if I use my Dodge Ram harness with a matching computer.
    • I have a few wires don't line up between my 2001 harness and the 2002 computer I am using.
      • C1 pin 10/11 (idle control valve 3/2) are inverse
      • C1 PIn 19/20(idle control valve 4/1) are inverse
      • C2 pin17 (condenser fan control) is present on 2002, but not on the 2001
      • C2 pin 19(A/C pressure signal) is present on the 2002 but not on the 2001
  2. Differences between C3 on TJ and 2001 Ram harness
    • C3 pin 13 (Overdive off switch base) doesn't exist
    • C3 pin 29((CCD(-) will go unused since my TJ and 2002 are PCI
  3. I need to wire C3 into tj connectors C103 + C104
    • I looked at the wiring schematics for these connectors
      • TJ C103 and C104... I was able to find some of the related circuits but not all. This is where my headache will likely occur.

Give me a day or two to find my notes when I did mine. I've misplaced them somewhere.
But yes you are correct that the TJ harness doesn't have the OD wire or the OD sense wire and you need to add them.

And yes if you are using a harness from a different year than your PCM you need to double check all your pinouts and make sure that they are in the correct location for that year PCM as there are minor differences between the wiring in the years.
 
Give me a day or two to find my notes when I did mine. I've misplaced them somewhere.
But yes you are correct that the TJ harness doesn't have the OD wire or the OD sense wire and you need to add them.

And yes if you are using a harness from a different year than your PCM you need to double check all your pinouts and make sure that they are in the correct location for that year PCM as there are minor differences between the wiring in the years.

Thanks, WIldman, I THINK I got it.

I took the following steps:
  1. Created spreadsheet with all the pins for C103, C104
  2. I scanned all the wiring diagrams for 2001 Service manual and marked them using my PDF editor with a red arrow
  3. I printed out all marked-up pages(only the pages that I found a reference to C103/104)
  4. I updated the spreadsheet with the translation of the circuit number to what it actually did and added a column with a page reference and whether I confirmed the pin location vs what was l listed on the C103/104 pinouts in step 1.
I found all circuits and confirmed all pins except for circuit G107, which I am a little unsure of. I did find a G107, but it's a ground with no specific pin called out.

For reference for others, here is my work for 2001 Tj using the service manual pdf:
C104
C103

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Attached is the marked-up service manual for connectors C103/C104 (rear of firewall and tie into PCM C3) for the 2001 TJ if anyone wants to go back and cross-reference in the future and save themselves some time.

All C103/C104 references are marked-up in the wiring schematics section with a red arrow pointing to the connector. I may have missed a few references, but only if they were redundant and I had already found the connection multiple times in other areas.
 

Attachments

  • 2001 TJ Service Manual-marked up wiring C103-C104.pdf
    8.1 MB · Views: 88
got an old boat that distracted me from this project but now that I have burned off the new boat fever I am back to working on the tj.

As right now I have a few open questions:
What has everyone else done for the automatic shifter?
I have an original 4cyl shifter and the bracket from the ram. Not plug and play or least not that I can tell. Any cheat codes to getting them to work or do I need to fab a new bracket?

Btw. I got my first start last week with full gauges except speedo( haven’t wired that yet).
 
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