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Unread 09-14-2011, 07:55 PM   #1
jjeeper
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2.4L to 4.0L swap questions

i have a 2003 tj with a blown 2.4L. so I bought a 4.0L out of a 98tj and it came with all the wiring and ECU.

My question is will the wiring from under the dash work properly with the new ECU from the 98? i was told its just gonna be plug-n-play, and would like for someone to confirm this.

thanks

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Unread 09-14-2011, 08:10 PM   #2
Wheelin98TJ
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No.

The gauges use different communication systems.

The '98 PCM will not operate the '03 gauges.
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Unread 09-14-2011, 09:13 PM   #3
jjeeper
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great! so now what do i do? find a older gauge cluster?
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Unread 09-14-2011, 09:54 PM   #4
Wheelin98TJ
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Nah, get a V8.

Autometer gauges should work for you.
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Unread 09-15-2011, 10:20 AM   #5
06pumpkintj
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Go with a 4bt swap and keep it a 4banger
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Unread 09-15-2011, 11:31 PM   #6
jjeeper
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i already have TOO MUCH into the 4.0L to change directions... lol and its been down to long! if this happens to you definitely go V8!

will i be able to make a 97-99 gauge cluster work or do i need to go the autometer route?
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Unread 09-15-2011, 11:53 PM   #7
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Painless makes a wiring harness complete with the ECU and the OBD II port. You just specify the model year and the ECU comes programmed. After that everything should be plug n play. You might check with them and see if their harness will be compatible with your gauge cluster.

It looks like I'm going to get a free 1997 TJ with a 2.5. I plan on swapping it to a 4.6 stroker and using the Painless harness to complete the swap.
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Unread 09-16-2011, 04:05 AM   #8
rda616
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I was able to sell my 4.0 and ax15 when I did my v8 swap and wound up with about $600.00 into my 5.9 conversion after parting with the old stuff.
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Unread 09-16-2011, 08:22 AM   #9
Wheelin98TJ
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Quote:
Originally Posted by jjeeper View Post
i already have TOO MUCH into the 4.0L to change directions... lol and its been down to long! if this happens to you definitely go V8!

will i be able to make a 97-99 gauge cluster work or do i need to go the autometer route?
The 97-99 gauge cluster will not work.

97-99 uses CCD Bus. Your 2003 uses PCI Bus.

Quote:
Originally Posted by Max-Q View Post
Painless makes a wiring harness complete with the ECU and the OBD II port. You just specify the model year and the ECU comes programmed. After that everything should be plug n play. You might check with them and see if their harness will be compatible with your gauge cluster.

It looks like I'm going to get a free 1997 TJ with a 2.5. I plan on swapping it to a 4.6 stroker and using the Painless harness to complete the swap.
Its not the wiring that is the problem, its the PCM. The 2003 PCM will not drive an older gauge cluster.

Are you sure Painless has that harness? They don't deal with Chrysler stuff too much.
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Unread 09-16-2011, 10:58 AM   #10
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Quote:
Originally Posted by Wheelin98TJ View Post
The 97-99 gauge cluster will not work.

97-99 uses CCD Bus. Your 2003 uses PCI Bus.



Its not the wiring that is the problem, its the PCM. The 2003 PCM will not drive an older gauge cluster.

Are you sure Painless has that harness? They don't deal with Chrysler stuff too much.
Yes. It's pricey but it does exist. http://www.4wheelparts.com/Performan...&t_pn=PWP65140
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Unread 09-16-2011, 11:25 AM   #11
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Quote:
Originally Posted by Max-Q View Post
Yes. It's pricey but it does exist. http://www.4wheelparts.com/Performan...&t_pn=PWP65140
Thanks for the link.

Wiring harnesses always seem overpriced, but after hacking together my own, I think they're worth it.
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Unread 09-26-2011, 01:05 PM   #12
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Quote:
Originally Posted by Wheelin98TJ View Post
The 97-99 gauge cluster will not work.

97-99 uses CCD Bus. Your 2003 uses PCI Bus.



Its not the wiring that is the problem, its the PCM. The 2003 PCM will not drive an older gauge cluster.

Are you sure Painless has that harness? They don't deal with Chrysler stuff too much.
ok so let me make sure we are all on the same page.
from the 1998:
-4.0L
-AX15
-under hood wiring
-PCM (grey box by battery)

from the 2003:
-wiring under dash
-gauge cluster

and with this combo my dash will NOT work?

$900+ for the painless wiring is out, so what are my other options?
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Unread 09-26-2011, 01:24 PM   #13
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Checl the motor mounts on the frame, i was told they are different from the 2.4 to the 4.0
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Unread 09-26-2011, 02:33 PM   #14
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Add move the motor mounts on the frame, and you'll also have to pull the whole 98 underdash harness, use the older gauge panel and probably mix/match a few AC and other underdash type stuff... AND the ABS and antilocks will probably be a huge problem too.


Sell the 4.0 you have and buy one of the correct years with underhood harness and PCM, and hassles get far less. ALL of this info was available here on this forum BEFORE you bought the wrong year 4.0.
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Unread 09-26-2011, 02:47 PM   #15
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Quote:
Originally Posted by Boodyrider View Post
Add move the motor mounts on the frame, and you'll also have to pull the whole 98 underdash harness, use the older gauge panel
This^^^^^^^

Under the dash is different wiring. I just did what you are doing. But I had a complete set of everything. Only thing that is same under the dash is the connectors for the vacuum lines, A/C heater controls the Air bag and those little lights under the dash and the door button. The rest all different. The gauge cluster will not plug into the harness for the 4.0 that you have. So inside harness and different gauge cluster at the least. Then the welding and cutting of the frame to fit in the 4.0....

Also the gauge you get will show the miles of the ECU that you have. So if more or less it will show.
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