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jeep tcm mod.

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QMartinez

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Discussion starter · #1 ·
All I have to say is it should have come from the factory this way. Most of my commute is flat freeway and I'm getting 2mpg better at 65 mph. I love it.

Thanks to everyone on this board for the knowledge to figure this out.

Q
 
#2 ·
This has got to be one of the dumbest things they ever did. I have no idea why they made the same transmission, and yet programmed one have an extra gear to get better MPG's with.

Glad your happy with it! It would be my first mod if my truck wasn't a manual.
 
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#3 ·
Discussion starter · #4 ·
I've had a chance to put a few hundred miles on, and I'm definately happy with this. This is by far the best mod I have done, and it only cost me 50 bucks and 5 mins.

I have 2002 QC 4x4 AWD 3:55 with 60,000 miles. I could get 20 miles per gallon if it was 90% freeway and I kept it under 60 mph. I could get 17-18 commuting 70 hwy/30city. This has been over the last year. I could never get it to average more than 20 because every hill or getting off and on the expressway would drop it considerably.

I can easily keep it at 23-27mpg at 60 or less, and 19-20 at 70. I averaged 23.6 at 90% freeway driving over 200 miles. I spent 5 mins in traffic and a couple freeway on and off ramps. I was extremely happy with this and my truck doesn't seem to have any issues with the higher gear.

I drive with the O/D off when under 45 mph so it hasn't affected that mileage at all at slower speeds, but it is definately better at higher speeds. I think I can get 20mpg doing 70 mph.
 
#5 ·
What is all required to do the tcm mod?
 
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#7 ·
Do I just look for a tcm from a 2003+ Ram?
 
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#8 ·
krs said:
What is all required to do the tcm mod?
Click to expand...
The part (TCM) and about 10 mins....2 5/16 screws off pull off connector remove old TCM replace new TCM plug in wire tighen screws....done

Now that you have the extra Gear, You need to get some lower gears in that rear end for the fun factor to come in to play.:D I really enjoy that mod along with the 4.10 gears. Better off the line and stays about the same RPM's on the highway. 2000RPM's @ 65mph with 4.10 gears 29Dia. Tires.(factory) I wise I would have done this back 9yrs ago!
 
#9 ·
Jastry said:
The part (TCM) and about 10 mins....2 5/16 screws off pull off connector remove old TCM replace new TCM plug in wire tighen screws....done

Now that you have the extra Gear, You need to get some lower gears in that rear end for the fun factor to come in to play.:D I really enjoy that mod along with the 4.10 gears. Better off the line and stays about the same RPM's on the highway. 2000RPM's @ 65mph with 4.10 gears 29Dia. Tires.(factory) I wise I would have done this back 9yrs ago!
Click to expand...
I have 4.56s already :woot:

So I should see a a little more performance gain? Or just mpg?
 
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#10 ·
QMartinez said:
I have 2002 QC.
Click to expand...
I was wondering what you were talking about cuz up where it says your vehicle you listed an 03, and with an 03 there is no need to do this, the extra gear is there already, but I see you have an 02 in this post. :mullet:
 
#12 ·
Thats works for me..I take it I just have to get a tcm from a 2003-2007 jeep or dodge with a 4.7?
 
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Discussion starter · #13 ·
I sold my 03 and bought an 02 a year ago. Just haven't changed it, sorry.

I bought mine from an 02 jeep grand cherokee... part # ends in 1905AB. There is another thread with all this info in the gen lll thread. check it out if you are interested in this mod. It is the best mod I have done hands down.
 
#14 ·
Thanks!!
 
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#16 ·
Yeah, I have the close to 35" tires on. I did not know the 5.7 tcm would work? Thats great to know.
I cant believe I slept on this mod. Thanks to QMartinez for bringing this to my attention :banana2:
 
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#18 ·
The only advantage to the Ram TCM will be slightly higher line pressures. Good for holding power, whether you feel the difference or not.

A transgo kit would be a good addition to firm the shifts up. Most of the firmness comes from the resistor that bumps line pressure, but it's highly recommended to do the kit with the resistor. The accumulator cover plate seems to be a weak link, transgo includes a beefier plate.
 
#19 ·
I have an 02 rango with a transgo shift kit but it already has the 5 speed tcm. Which I think was an extra computer, right? Anyways it had an 03 TB too I found that out when I tried to buy a BBK for it. Wierd cause it was made in Jan '02.
 
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