Transmission swap help

You gotta Love these old VG30E/i powered beasts, raw truck DNA to the core.

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AdamHarris
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Joined: Wed Jul 26, 2017 3:25 pm
Location: Alabama

Transmission swap help

Postby AdamHarris » Wed Jul 26, 2017 5:55 pm

I am trying to swap my 3 speed automatic in my 87 pathfinder for a 4 speed automatic out of a 94. What equipment do I need to get out of the 94 to put in the 87 for this to work? I am thinking i just need the TCM and add some wiring to the existing harness and add an overdrive off switch, or is it more complicated than that. Please any information helps. thanks


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smj999smj
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Postby smj999smj » Thu Jul 27, 2017 1:07 am

I remember people asking about this swap years ago and even back then most considered it too much trouble than the swap was worth. First of all, if the 87 is not a V6 model, then we can stop right here as the V6 trans will not bolt up to the I4. The A/T subharness, known as the "terminal cord," runs from the trans case on the 4-spd. trans and plugs into the main harness in the engine compartment. You will need the main harness assembly, which runs along the back and sides of the engine compartment, behind the left fender, behind the dash and down to the ECM and, if I'm not mistaken, all the way to the fuel pump and tail lights. Then you need the ECM and TCM. If the engine that the 4-spd. trans came from is a VG30E, then you will have to convert your VG30i to a VG30E in order for the EGI harness to work with the donor harness AND because the donor ECM is designed for MPI, not your VG30i's throttle body injection. This may also require you to swap the fuel pumps. Of course, you'll also need the shifter, which has the O/D button built into it.
So, as you can see, it's a real pain in the tail and a lot of work and expense to put into an 87 Pathfinder. Even though it would be nice to have the overdrive, cost and labor makes it much more practical to have the 3-spd. rebuilt by a reputable transmission shop. A good transmission man may even be able to "beef it up" some to make it a little more durable.


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