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Discussion Starter #1
Hello everyone, I just picked up an beat up 2004 Envoy XUV to be a donor for a 5.3 swap into my 95 AWD Astro which just lost it's transmission and is pretty tired at 280k miles. My questions start with the wiring... I want to swap the engine and transmission into the astro and am going to take as much of the wiring, hoses, etc. as necessary including the OBD2 if possible (Astro is only OBD1).
I've got the front end of the Envoy removed and a fair amount of the wiring unplugged and labeled (on the engine). I'm not really sure where to go from here though. Let's start with the fuse box, I've watched you tube videos that say you only need the middle block. Is that correct? What about the TCM or whatever these things use to control the transmission.. Is that integrated into the PCM? I can't find any clear answers on the internet to tell me if it's a PCM or an ECM for the engine and TCM for the trans. Thoughts?
Sam
 

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I think you have a huge job ahead of you.

Before you start, let's make sure it fits
Was the Envoy 4 wheel drive?
If not, it probably won't mate with the Actor's transfer case.
Even if it is 4x4, the two transfer case are different, but not by much, they should have the same bolt pattern.
 

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Sorry, the phone spelled Astro wrong and we no longer have an edit button
 

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Discussion Starter #5
Thanks for the response. The envoy is 4wd but I plan on doing a transfer case swap to something that's manually shifted and is as robust as possible.
 

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Hmmm, the Astro is kinda a cab over, the transfer case shift lever usually mounts behind the engine, where can you mount the mechanism?
 

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Discussion Starter #7
It's actually not that tricky... So the transfer case winds up being somewhere behind the front seats in the centerline of the vehicle (as it is with the TB/Envoy). It's actually not that much further back in the Astro than in the TB.. maybe 6-10"... idk, that's just a guess. So anyway, you attach a manual shift lever to the side of the xfer case and run a shift cable forward and up through the floor to a lever next to the driver's seat. You can either build your own simple lever or just grab an available one out of the junkyard. Guys have used the Jeep Liberty lever which is pretty compact and attractive. My goal would be to use something that's as small as possible and tucks up tight against the seat since whoever is sitting in the passenger seat seems to love to wander to the back for various reasons during road trips. The van is set up for camping/overland adventures so there's a bed and movies and snacks in the back.
 

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Discussion Starter #8
BTW, any idea what that box is on the firewall next to the brake booster? It tucks up in the corner behind the fuse box
 

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Got a picture?
 

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I would say it's the engine computer.
 

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I've always heard that 95 was the transitional year for OBD, 94 being OBD I and 96 OBD II, 95 referred to as OBD 1.5. Even with the swap over of all the computer hardware and wiring I'm not sure that there wouldn't be unforeseen issues with such systems as radio, HVAC, maybe even anti-lock brakes.
 

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Discussion Starter #13
Hey RayVoy, it's not the PCM. That's a big silver box sitting inboard of the fuse box. It's pretty big and pretty obvious. I'm not sure what this little module is but it's something and is there for a purpose - I'm just not sure what.

GarageRog - yeah, it's definitely a transition yr and GM was using up all their old stock while they were building the 95's. Mine is definitely OBD1 and all the accessories just run in their own little way out of the fuse box. It's pretty straightforward. The gauges might be a chore but people have tackled that in the past so info exists on how to get it done.
 

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Hey Bad, is there a GM part number, we could Google it
 

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I think this is guna be a pretty damn sweet truck when your done.

Al
 

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Discussion Starter #16
TheGawd, thanks brother. I'm thinking so... Getting an engine with decent power should really change the personality of the van and give it the balls to match its rugged good looks. Haha. I've got a water purification system and 10 gallon tank pieced together and 300 amp hrs of batteries for a house bank that all need to go in. Some solar, an awning and a high mounted external water tank for showers will make this all kinds of comfy. The full sized bed in back is already a comfortable way to spend time in the mountains. I've got the Mexico Gambler 500 in March so this swap needs to get underway in a hurry.
 

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Discussion Starter #17
BTW, that little box is the throttle control modulator or some such nonsense... Basically, its one more separate and expensive little box to break in an overly and unnecessarily complex system. It's a part of the controls for the drive by wire system.
 

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Yup...the drive by wire crap.

I like your manual t-case idea. Would be nice to have that.

Have you looked in swapping the oil pan? The thru design of the Envoy makes the 5.3 much taller than in needs to be since you will be retaining your 4x4 drivetrain.

IIRC the 04 was the LM4 and did not have the AFM issues, so that is a plus.
 

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Discussion Starter #19
Yup...the drive by wire crap.

I like your manual t-case idea. Would be nice to have that.

Have you looked in swapping the oil pan? The thru design of the Envoy makes the 5.3 much taller than in needs to be since you will be retaining your 4x4 drivetrain.

IIRC the 04 was the LM4 and did not have the AFM issues, so that is a plus.
Yeah, no AFM is a good thing. The oil pan isn't going to work but not because of the height.. the front hump sits right where the Astro front diff sits so I'll need a rear hump / truck pan. Even then, it doesn't fit and needs mod. I've got a cheapo steel oil pan inbound from ebay and the pan is to lift the engine an inch or so, shove the engine backwards as far as it'll go, move the front axle forward an inch, and lower the front diff and inch. All that should give me the clearance I need. There's some other motivation to do all that shuffling around too... Moving the front axle forward helps approach and also centers the wheels in the front wells. Raising the engine a bit gets the oil pan and tranny away from the trail. And moving the engine backwards helps weight distribution in a front heavy turd of a vehicle and helps me in the next phase which is to shove the rear axle backwards a few inches to help in the departure angles. There's going to be some trial and error making everything fit and finding driveshafts but it'll be fine. Solutions will be found when problems are identified.
 

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Discussion Starter #20
Continuing to make slow but steady progress. Got a few minutes to work on it so went out and pulled the transfer case. It's about ready to come out.
 

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