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aw4 issues

carter442

NAXJA Forum User
Location
tipton in
ok so i replaced the neutral safety switch the other day in my 91 xj. the case was cracked and it would not start in neutral or park. After i replaced it when i put the transmission into drive it starts in 4th gear. so i double checked my connectors and those were fine cleaned them just to be sure. Checked tcm fuse just fine. I checked the tcm just to be sure this is what i found.

with tcm plugged in- drive starts in 4th, manual 3rd is 3rd, manual 1/2 will start in 1st then shift to 2nd. sometimes when slowing down will not downshift to 1st and will start in 2nd and not downshift.

with tcm unplugged- d starts in 4th manual 3 is 3rd manual 1/2 is only 1 no upshift at all.

is this a tcm related problem or is my nss still misadjusted?
 
Still badly miss adjusted. To get it close... Put on the e-brake and or chock the wheels. Put the shifter in reverse. Loosen NSS and turn till your reverse lights come on. Yes the NSS controls your reverse lights. When they come on tighten the NSS back up. Shift trans back to park and see if it starts. Just tweak from there if needed.
 
As far as the shifts go. Adjust your tv(throttle valve) cable/down shift cable/detent cable. What ever you may know it as. There is a tread on here how to do it.
 
Just so its clear my jeep starts in both park and neutral but when it is put into drive and i accelerate it is not in 1st it is in 4th this situation is nss related?
 
Just so its clear my jeep starts in both park and neutral but when it is put into drive and i accelerate it is not in 1st it is in 4th this situation is nss related?
 
It's a voltage problem. I know you said you checked the fuse but did you use a test light or DVOM to check power and grounds to the TCU?

Default gear for the AW4 that has no power is 4th gear. Your symptoms are telling me there is no voltage either to the tcu or down to the trans.. Check the other trans connector near the NSS connector and make sure it is secure.
 
and thats is what i thought. at first i thought i fried my tcm but last night when i was driving it with the tcm plugged in in manual 1/2 it DID shift to 2nd it was in no way shape or form normal but it did shift. I was under the impression that an aw4 with no power will not shift into 2nd since even manual 2nd is controlled with a solenoid.
 
I checked the tcm fuse with a multi meter. i took it out and used the continuity to test it. with it out the power/comfort switch has no indication light and with it plugged in the light works correctly.
 
so i tried to tweak the nss till i get reverse lights but they did not come on. when i first put the nss on i had my reverse lights. i think i am going to put the old nss back on and see if i still have these symptoms just to be sure.
 
ok so where am i testing on the tcu? i will make sure there is power to the tcu then from there where will i test? where is the transmission connector thats near the nss?
 
Try this:

Cruiser’s Trans Plug Refreshing

Over near the transmission dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and transmission solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.
 
Additionally, if your Jeep is an 87 to 90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse.
Revised 9-10-2012

 
i sprayed both of those connectors out and neither looked like they were shot il recheck basically when i replaced the nss i unplugged bother of those connectors and the nss thats all i messed with when replacing it.
 
ok so i tested the d16 pin of the tcm connector and its showing 12 volts with key on and 0 with key off. i assume from that i have power to the tcm so from there where on the transmission does power go?
 
Those are symptoms of a bad TPS.

Oh, I see you have a 91, the 87-90 TPS has a connector for the trans. , not sure if the OBD-I uses TPS values for shift points.

Sorry for the no-help.

Will check my 95 ZJ FSM for info and post up.
 
I just looked at my old 87 wiring diagram and it shows that the TCU itself, D7, and it's "shift point logic", C5, circuit ground at the engine dipstick tube stud.

Could that set of grounds gotten disturbed when unplugging the NSS connector?
 
I have a wiring diagram for this but i dont see where the tcm grounds. I am studying it very hard to figure this out. I am going to try and rule out the tcm first. while I am at it I will check the dipstick ground while i am at it
 
ok i removed the grounds cleaned them and stud. none of which were corroded drove it still same thing high gear in drive. On a side note in manual 1-2 it would shift to 2nd gear. From this should i conclude that my tcm is good?
 
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