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1999 aw4 "no reverse"

moneypitxj

moneypitxj

NAXJA Member #565
Location
york, pa
my tranny wont go into reverse, except in 4-lo.
i shifted through the x-fer case and reverse only works in 4-lo.
the tranny has about 90,000 miles.
has anyone had this problem?
im mean its only a '99 and if the tranny is going out that is pretty crappy.
 
i can put it in reverse but the tranny acts like it is still in neutral.
but i can get reverse only in 4-lo.
no other gear on the x-fer case.
 
The shifting is accomplished by the TCU (transmission control unit) using signals, especially the TPS (Throttle Position Sensor) input, then it controls which solenoids in the tranny get power. The solenoids actuate valves that control fluid flow. Usually the problem is not mechanical inside the tranny- don't let a shop rebuild it until other sources are ruled out. So, it could be wires shorting (rubbed through insulation) that are moved when you shift to 4lo so work again, or a faulty TPS. Weird shifting is a normal occurence from a failing TPS, maybe with high idle if the TPS is bad enough. There was a posting of which solenoids get power for which gear, searching AW4 should find it. If the TPS checks out, I would then look at electical signals going to the tranny and see if there is a wiring/connector issue. If the signals are all OK, then solenoids can be reached through the pan, tranny in jeep. Both the tranny mechanical stuff and the TCU are really robust. Let us know what you find!
 
4xBob said:
The shifting is accomplished by the TCU (transmission control unit) using signals, especially the TPS (Throttle Position Sensor) input, then it controls which solenoids in the tranny get power. The solenoids actuate valves that control fluid flow. Usually the problem is not mechanical inside the tranny- don't let a shop rebuild it until other sources are ruled out. So, it could be wires shorting (rubbed through insulation) that are moved when you shift to 4lo so work again, or a faulty TPS. Weird shifting is a normal occurence from a failing TPS, maybe with high idle if the TPS is bad enough. There was a posting of which solenoids get power for which gear, searching AW4 should find it. If the TPS checks out, I would then look at electical signals going to the tranny and see if there is a wiring/connector issue. If the signals are all OK, then solenoids can be reached through the pan, tranny in jeep. Both the tranny mechanical stuff and the TCU are really robust. Let us know what you find!
Click to expand...
Not reverse, the TCU has nothing to do with Reverse or park.
The shaft that the NSS is attached to connects to a valve for revese.
With the TCU unplugged you will have Manual shifting only.
 
He's right. The trans computer just controls the solenoids and the solenoid arangement doesn't change between park, reverse, and neutral. So if 1st gear works, it's not the solenoids causing your problem. That said, it would be curious if reverse worked when you pulled the trans computer fuse.

With it in Reverse, does it seem like the tranny is in park (vehicle won't roll) or does it seem like neutral (free to roll)? When it drive, does the indicator by the shift lever look like it's inthe right place? I'm thinking perhaps it's just a matter of adjusting the shift cable..
 
It sounds to me like reverse is slipping badly.

The gear reduction of 4Lo is allowing the slipping to have just enough bite to actually move your Jeep. With plenty of clear space behind the Jeep, you can test my theory by putting it in 4Lo, shift to reverse, and let it start rolling back. Once it starts to roll, step down on the gas pretty hard. If the RPMs jump way up without a coresponding jump in motion, then it's still slipping.

Start scouring the junkyards, or have it rebuilt if this is the result (which I'm pretty sure it will be).
 
Kuasimodem said:
It sounds to me like reverse is slipping badly.

The gear reduction of 4Lo is allowing the slipping to have just enough bite to actually move your Jeep. With plenty of clear space behind the Jeep, you can test my theory by putting it in 4Lo, shift to reverse, and let it start rolling back. Once it starts to roll, step down on the gas pretty hard. If the RPMs jump way up without a coresponding jump in motion, then it's still slipping.

Start scouring the junkyards, or have it rebuilt if this is the result (which I'm pretty sure it will be).
Click to expand...

yea i think this might be the prob kuasi.
with this snow we just got i had to beat it a little to get it up our driveway.
then it started acting up.

i should have just drove my xj in that 14" of snow, that would have worked good.
this happened on the wifes wj, still a stocker.
i guess i will start to look around for a new tranny.

anyone have a good aw4 at a decent price?
this year is starting out so well for saving money.
i just spent over $1000 on our 2 dogs.

thanks eveyone for the good info.
 
moneypitxj said:
yea i think this might be the prob kuasi.
with this snow we just got i had to beat it a little to get it up our driveway.
then it started acting up.

i should have just drove my xj in that 14" of snow, that would have worked good.
this happened on the wifes wj, still a stocker.
i guess i will start to look around for a new tranny.

anyone have a good aw4 at a decent price?
this year is starting out so well for saving money.
i just spent over $1000 on our 2 dogs.

thanks eveyone for the good info.
Click to expand...


Wait wait wait! Are we talking about an XJ, or a Wj here? The Wj tranny is NOT an AW4 but a 42RE (and a completly different beast) which was used behind the 4.0ltr in the Grands form 1993 to 2002.
 
it is a 1999 wj.
i tried doing a search on the kind of tranny and couldnt find anything.
so i just guessed it was the same as the other jeeps.
sorry about that. so it is a 42RE tranny.
anyone know could it be a differant problem with that kind?
 
The chrysler tranny in the WJ is anything but bulletproof. I can not stand chrysler built xmissions, i think they should close the Kokomo transmission plant and buy Aisin Warner or Jatcos
 
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