4.0 Auto to Manual Transmission swap

Matt789

Matt789

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Joined
Jun 14, 2021
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Location
Maryland, USA
Hello everyone. Brand new to the forum and looking for some input. I have a 2000 4.0 Auto and a 1999 4.0 Manual. I would like to swap the trannys between the two Jeeps. I bought a 99 PCM from an Auto and a 2000 PCM from a Manual. Now I’m learning that 99-00 there was a transmission change. Both Jeeps are 4.0 sports (Not Rubicon). Can I swap the trannys and use the new PCMs to make this work? If so, will I need more parts than just the PCMs I ordered or will everything work that transfers from the Jeeps? Thanks in advance for the advice.
 
A 2000 PCM programmed for the NV-3550 manual transmission will still work fine for the AX-15 manual transmission used in 1999 and older TJs. So your PCMs should work, though make sure the PCM for the 2000 is for the type of ignition it has... with a distributor cap and separate ignition wires, or the newer coil rail ignition system that doesn't use a distributor. 2000 was a transition year for the ignition system so just make sure you have the PCM to for your particular ignition system.

The 231 tcase input shaft made for the 1999 is short since it's made for an AX-15. It's not long enough to seal the output shaft opening for the 32RH. That'll let the 32RH dump lots of ATF out its output shaft opening. No worries though, both Teraflex and Summit Racing have extended output shaft seals for the 32RH that work perfectly to seal it to the 231's short input shaft.

At least you'll have access to both Jeeps and can swap parts between them. I did an AX-15 to 32RH conversion on my '97 TJ and had to figure out what additional parts, mounts, etc. I needed as I went.

Also, the hard coolant lines leaving the 2000 32RH may or may not fit your '99, locations of a few things changed where the hard line routing is concerned. The hard lines that came with my used 32RH couldn't be used on my '97, I had to order a set of new hard coolant lines.
 
What about the transmission control unit and harness connector ?
Am I remembering incorrectly that the earlier Jeeps had a TCU unlike the later Jeeps that had the TCU incorporated into the PCM ?
 
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Jerry Bransford said:
A 2000 PCM programmed for the NV-3550 manual transmission will still work fine for the AX-15 manual transmission used in 1999 and older TJs. So your PCMs should work, though make sure the PCM for the 2000 is for the type of ignition it has... with a distributor cap and separate ignition wires, or the newer coil rail ignition system that doesn't use a distributor. 2000 was a transition year for the ignition system so just make sure you have the PCM to for your particular ignition system.

The 231 tcase input shaft made for the 1999 is short since it's made for an AX-15. It's not long enough to seal the output shaft opening for the 32RH. That'll let the 32RH dump lots of ATF out its output shaft opening. No worries though, both Teraflex and Summit Racing have extended output shaft seals for the 32RH that work perfectly to seal it to the 231's short input shaft.

At least you'll have access to both Jeeps and can swap parts between them. I did an AX-15 to 32RH conversion on my '97 TJ and had to figure out what additional parts, mounts, etc. I needed as I went.

Also, the hard coolant lines leaving the 2000 32RH may or may not fit your '99, locations of a few things changed where the hard line routing is concerned. The hard lines that came with my used 32RH couldn't be used on my '97, I had to order a set of new hard coolant lines.
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Thank you for the write up. Question- is the transfer case input shaft still and issue if I move the transfer cases with the transmissions? Can I do that? Thinking I’d have to swap the drive shafts between Jeeps as well.
 
Matt789 said:
Thank you for the write up. Question- is the transfer case input shaft still and issue if I move the transfer cases with the transmissions? Can I do that? Thinking I’d have to swap the drive shafts between Jeeps as well.
Click to expand...
Yes the t-cases can be swapped. For sure you'll need to swap the front driveshafts, the one for the automatic has a smaller diameter to clear its transmission pan.
 
CharlesHS said:
What about the transmission control unit and harness connector ?
Am I remembering incorrectly that the earlier Jeeps had a TCU unlike the later Jeeps that had the TCU incorporated into the PCM ?
Click to expand...
No TCU from 97-02. That happened in 03-04 with a stand alone TCU for the 42RLE which was then integrated into the PCM in 05-06.
 
mrblaine said:
No TCU from 97-02. That happened in 03-04 with a stand alone TCU for the 42RLE which was then integrated into the PCM in 05-06.
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Im into the swap now and when I went to move the shift interlock cable/mechanism from one Jeep to the other, the ignition switches are different. The ignition for Jeep that was manual doesn’t have the block on the back side to plug it into. It has the small white connector for the wires, but not the square block. Also the manual has a levered key release. Do I need to swap the ignition switches also?
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Matt789 said:
Im into the swap now and when I went to move the shift interlock cable/mechanism from one Jeep to the other, the ignition switches are different. The ignition for Jeep that was manual doesn’t have the block on the back side to plug it into. It has the small white connector for the wires, but not the square block. Also the manual has a levered key release. Do I need to swap the ignition switches also?View attachment 262204View attachment 262205
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Yes, there is also a very small piece of pot metal that is easily lost, don't lose it.
 
Matt789 said:
Im into the swap now and when I went to move the shift interlock cable/mechanism from one Jeep to the other, the ignition switches are different. The ignition for Jeep that was manual doesn’t have the block on the back side to plug it into. It has the small white connector for the wires, but not the square block. Also the manual has a levered key release. Do I need to swap the ignition switches also?View attachment 262204View attachment 262205
Click to expand...
Never mind. Realized I could remove the part from the bottom each ignition cylinder.
 
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