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AW4 modification

Black1990jeep

NAXJA Forum User
Location
california
On my 1990 XJ with AW4 tranny, prior owner added a switch to allow one to select 1st gear when in the 1/2 shift position. this switch also will prevent 4th gear in OD shift position, allowing it to only go as high as 3rd gear, unless switch is set to the 1st gear position. thus the switch has position 1 / 4 or 2/3 .

so now the funny thing. since I can be in OD with the shift lever, and force the tranny into 3rd with the added switch,this is what happens.... if I am in OD and select the switch to put me in 3rd gear all is fine, she down shifts to 3rd, but when I switch the switch back to give me 4th again, she goes to forth, BUT the torque converter will not lock. however if I shift to 3rd from4th using the shift lever (in OD 4th gear, and use lever to go into 3rd)and then go back to 4th by going into OD the toque converter does lock

when in forth at 65 mph tach reads 2000 rpm, when locked, but after I go to 3rd using the modified added switch, then back again to 4th, the converter slips, and I am at 2500 rpm, then I shift using the lever to 3rd, (she goes into 3rd) then back again to OD, she goes to 4th with no slip, back to 2000 rpm

So what is going on here?
 
Have you checked RaD's site, he got a lot of diagnostic info on that type of set-up?
 
Do a YouTube search for nickintimefilms and the nifty shifter. I personally believe that's the best way to manual shift an aw4

Sent from my SM-G950U using Tapatalk
 
So what does the stock shift lever do? does it simply make or break electric contacts to shift the tranny solenoids, or does it mechanically move the gears?

how is electrically by passing the brain with a switch different than using the shift lever as far as the tranny is concerned and torque converter lock up. I under stand that lock up is activated by a solenoid, is there any other way that lock up is obtained other than the solenoid?
 
The factory shifter controls the NSS and the plunger on the valve body.
 
Watching that YouTuber (3 videos I believe) will explain almost everything.

Sent from my SM-G950U using Tapatalk
 
The factory shifter controls the NSS and the plunger on the valve body.

thank you so the stock shifter lever mechanically moves the solenoids them, correct? does it override the electric signal to them then?

with my added on switches I can force the tranny to stay in 3rd gear even when in OD shifter lever position

but what is the NSS? sorry I am brand new to automatics.
 
No the solenoids are electrically operated only. The Neutral Safety Switch provides input to the TCU.
 
I would look at how your switch has been wired. I had the same thing on my 92 but never had any issues. Possibly something back feeding into tcu and causing it to shut off TCC or something in the brake switch preventing TCC lock up. Shift lever position should have no effect on that.
 
Can someone explain how this switch works to lock in 1st and lock out 4th? At first I thought it just disconnected either solenoid, but per the attached you'd only get 1 & 4 or 2 & 3. Been wanting this 1 and no OD functionality but it seemed that full blown control would be required, not just a simple switch. Maybe it's now that simple. Any info would be helpful.
 
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