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Holding AW4 in First

98XJSport

98XJSport

Destiny is the rising sun
Location
Western Maine
Well Ive been reading up on manually shifting the AW4, and found a decent writeup here:
http://naxja.org/forum/showthread.php?t=924795&highlight=lock+first+gear

But the more I think about it, I really don't want to shift through all the gears, I simply want to be able to hold first keep and keep it out of second.

Will putting the tranny selector into 1-2 and cutting power to the TCU do this? That's what the writeup seems to imply, but Im not sure how the other wire used ties in. Im thinking that it is just to move it up through the other gears, which I think the AW4 does a decent enough job of as it is.

Just looking to keep it in 1st for climbing/hill decents etc while I remain undergeared at the axles.

Thanks for any help.
 
That would be great if I wanted to shift through all the gears, and spend $150 bucks doing so. Im familiar with BrettMs work, it's a great product. But it would be gold horseshoes on a jackass, I just want to hold 1st on occasion.
 
My experience with my AW4 (90 XJ) is that it always holds first in the 1-2 position, and doesn't want to go to 2nd. That is why I am looking into the shift mod - so that I can get it OUT of first....
 
Odd, I have read that it should hold first until it hits second, but will never go back to first. Or at least that's what Ive read on here that the AW4 is designed to do. :dunno:
 
Mine will hold first until near red-line RPM then shift at a very inconvient time when in the mud. In the rocks it hardly ever shifts for me, and will indeed go back to first.
 
My rock buggy uses a 4.0/aw4/231 from an 88 XJ. I mounted the Ecu and the trans computer in the cab of my rig where they are easily accessable and away from water. When I wan to keep it in 1st, I simply unplug the trans comp and put it in 1-2. It will not come out of first until you shift to 3 and it skips 2nd without the comp hooked up. Its like a manual without the clutch, but you lose 2nd. Thats why I really only do it on decents. Killing the power to the trans computer will do the same thing. Dang, I'm glad you said that. I just need to put a toggle switch on it.

sorry, im done babbling. Hope that helps
 
Thanks, that's basically exactly what I was wondering. It would be nice to do the other shifting options, but really Ive only wanted to be locked into a lower gear on decents or if slooowly pulling something.
 
Okay, here you go.

Wired normal.

D = All ranges, shifts normally.
3 = 1st, 2nd, 3rd, shifts normally.
1-2 = 1st from 0 - +/-4,800 rpm, shifts to second above. Will downshift into 1st when the computer says it's appropriate (meaning engine RPM will be +/- 4800 rpm, VERY HARSH SHIFT!).

2nd Gear Swtich in the 2nd position

D = 2nd and 3rd only.
3 = 2nd and 3rd only.
1-2 = 2nd only.

2nd gear switch in normal position, same as no mods.

TCU Kill switch on, killing TCU power.

D = 4th gear
3 = 3rd gear
1-2 = 1st gear (unless 2nd gear switch, then depends on switch position)

Personally I vote to put a swtich in. 2nd is VERY handy offroad, especially when running with a group.
 
You can also get a Compu-Shift module. They have a limited number of XJ AW4 units in stock again, and they work on late models.

I'm trying to dig up the email from compushift I got a couple weeks ago about it, will post here if I find the info. :)

EDIT:

here we go.

http://www.aftermarket-innovations.com/
 
Last edited:
Interesting, I will have to play with this a bit this weekend.

Probably sets a CEL for a OBD2 XJ though, Im guessing?

 
98XJSport said:
Interesting, I will have to play with this a bit this weekend.

Probably sets a CEL for a OBD2 XJ though, Im guessing?
Click to expand...

I don't think the Compushift does, as it doesn't cut power to anything the way most toggle switch systems does. It goes inline between the TCU and trans and swaps signals around.
 
cal said:
I don't think the Compushift does, as it doesn't cut power to anything the way most toggle switch systems does. It goes inline between the TCU and trans and swaps signals around.
Click to expand...
Yes it does. From their website...
CompuShift Plus 96-2001*
Jeep Cherokee 1-2 Shift Control Computer for 1996 thru 2001 year vehicles. *Note: Because of the change from the OBDI to the OBDII Code in 1996+ vehicles, the operation of the CompuShift Plus with turn on the Check Engine light. It will remain on until reset with a code reset tool. This does no harm howver if you do not feel comfortable with this situation, do not order or install it.
Click to expand...
 
GSequoia said:
Okay, here you go.

Wired normal.

D = All ranges, shifts normally.
3 = 1st, 2nd, 3rd, shifts normally.
1-2 = 1st from 0 - +/-4,800 rpm, shifts to second above. Will downshift into 1st when the computer says it's appropriate (meaning engine RPM will be +/- 4800 rpm, VERY HARSH SHIFT!).

2nd Gear Swtich in the 2nd position

D = 2nd and 3rd only.
3 = 2nd and 3rd only.
1-2 = 2nd only.

2nd gear switch in normal position, same as no mods.

TCU Kill switch on, killing TCU power.

D = 4th gear
3 = 3rd gear
1-2 = 1st gear (unless 2nd gear switch, then depends on switch position)

Personally I vote to put a swtich in. 2nd is VERY handy offroad, especially when running with a group.
Click to expand...

I don't want to be contradictory, but...
The TCU mod on the OBDII Jeeps is proported not to work. The poster has a 1998 I believe, an OBDII unit.
IS the only problem with the Renix/OBDI AW4/TCU mod that the Check Engine light will throw a code?
 
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