4.0 to 4.7 HO drivetrain swap - Page 3 - JeepForum.com
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Unread 07-25-2013, 01:03 AM   #31
99WJ539918
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1999 WJ 
 
Join Date: Aug 2008
Location: , Northern New Jersey
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Quote:
Originally Posted by CopperDeer View Post
There's a little more wiring necessary then I had thought or hoped, but it's nothing serious. The engine would probably even run without it but the transmission won't be happy, maybe even not functional.

I'm just going to make the necessary changes / additions from the drivetrain harness to the chassis by running a few new wires. There's around 10 mismatched or missing wires, mostly transmission related. I need to get an 04 FSM, I have an 01 FSM and it seems to match my 99 chassis's wiring perfectly but there are many discrepancies between it and the 4.7 engine harness.

I'd love to cut the pigtails I need from a 4.0 at the junkyard + my donor and just build a 4-6" long "conversion harness" with the 4.7 chassis and 4.0 engine connectors. It would be nice to avoid hacking up my WJ or the 4.7 engine's wiring and the next time I want to pull / swap the engine it won't require this process all over again... hopefully that's quite a while down the road but still. Screw it, I'll just cut the connectors for the jumper harness off my 4.0.

Donor drivetrain is almost out. Getting the hoist tomorrow, then it's off to the shop for a week or so tomorrow night. I probably won't be online much but I'll be taking pictures and notes and will start a new "cleaned up" thread with the specifics when I get the chance.

Good idea.

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Unread 07-25-2013, 01:21 AM   #32
elcorvino
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You don't know the maintenance history of the vehicle. I wouldn't risk it or you may end up looking for another donor.
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Unread 07-25-2013, 05:47 AM   #33
CopperDeer
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It looks to have been excellently maintained. The water pump looks relatively new. The fluids were fantastic. Runs great. It just may have already had a head gasket done, hopefully it was done well and that will give me longer life out of it. Too late to back down now!
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Unread 07-25-2013, 06:22 AM   #34
CopperDeer
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Got the 04 FSM thanks to an awesome fellow forum member hookin' it up. Just need to map out all the wiring differences in a nice and neat little Excel sheet and build a jumper conversion harness this weekend. Everything is back right on track.
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Unread 07-25-2013, 01:00 PM   #35
CopperDeer
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Was expecting to have to get my POS trailer out but how do you like this, a vehicle than can fit it's own drivetrain (two at the same time!).

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Unread 07-26-2013, 09:04 AM   #36
troy70
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PM sent. What's the plan for the interior? I'd be interested in some of the trim work (center console from the ash tray to the rear drink holders.

Thanks!
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Unread 08-03-2013, 12:58 PM   #37
CopperDeer
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Got everything swapped over this week. Mechanically, the swap was as much if not easier than swapping a 4.0 drivetrain back in. BTW, the motor mount brackets, crossmembers, exhaust, etc are all identical. The only things that are slightly different / need some modification are the throttle cable, fuel line routing in the engine bay, and possibly the transmission shifter cable. Use the vacuum/PCV routing from the 4.7 and everything hooks up like it was meant for it.



The engine cranked and started for about .2 seconds the first time and that was it. Now there's no fuel pump, no spark, nothing. The PCI bus is dead and there is no communication between modules. The instrument cluster is dead, my basic scan tool only sees "Engine RPM" and "TPS %". I tried my old PCM & SKIM and hooked up my scan tool and behavior was the same.

I towed it over to the dealer on my trailer and they were nice enough to hook up the DRB-III in the parking lot for free. Said the DRB-III had no communication with the PCM/vehicle and couldn't do anything. Suggested there is a short or mismatch in the wiring somewhere causing the PCM to lose communication. We talked about people having failed/shorted CKP sensors causing the same thing. The tech I talked to said he would unplug sensors & modules by process of elimination until PCI bus communication comes back online then make repairs from there. He did not think the 2004 4.7L engine in a 1999 4.0 chassis was the problem and said with a little wiring modification it should work perfectly. He said even still, it should start and run and just throw codes for the mismatched stuff.

At least I got all the mechanical work necessary done for doing the actual swap in the time and budget allotted in the shop. Now the Jeep sits in my uncle's backyard until we can get this electrical issue straightened out. I have to go back home to NC in a few days but he said the thing can sit parked there until the apocalypse as far as he cares. If I can't get it fixed in the next couple days I'll have to try again when I visit next month....
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Unread 08-03-2013, 06:43 PM   #38
rm2001wj
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Maybe you ave already done this, but here goes anyway. Assuming the 04 HO PDC, check Fuse 19 (10A). The current for PCM operation goes through that fuse, and if it's blown, the PCM can't communicate.
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Unread 08-03-2013, 07:23 PM   #39
CopperDeer
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Yeah I checked the fuses particularly the PCM one. I read of someone having a bad CKP with the exact symptoms I have and the dealer tech suggested just going sensor by sensor wire by wire, since everything worked before the swap we assume something was damaged during the swap...
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