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AW4 Starts in Second When Cold / Fails Manual Shift Test

4LowandGo

NAXJA Forum User
Hello All,

I have a '92 XJ with a 4.56 gears, a high output motor, a 4.0 and an automatic AW4 transmission. When the vehicle is cold and I start it up and put it in drive it will start out in second gear. Once I go through the gears once or twice it will then drop down to first and shift through all the gears like normal. When the engine is hot it will never start out in second and it will always start out in first gear. I've adjusted the throttle cable, replaced the TPS, and cleaned the NSS. The reverse lights work and the vehicle will start in neutral and in park like its supposed to. I've checked the fluid level a few times and everything looks good. I have even bought an extra TCU from the junkyard and swapping it in didn't help at all.

Here's a good lead... When the vehicle is cold it will fail the manual shift test when the TCU is unplugged. As soon as I drive 1/4 mile or so it will then drop down to first and act normal. I've seen posts on the manual shift test, but I haven't found much info on what to do if it fails. What do you reccomend?
 
Cold, TCU plugged in:
Tranny starts in 2 and will upshift and downshift properly (except 1st).

Hot, TCU plugged in:
Tranny starts in 1 and will upshift and downshift properly in all gears.

Cold, TCU unplugged:
You can manually shift through gears, and all works properly, except for 1-2?

Hot, TCU unplugged:
All gears work normally.

What does it do when cold and TCU unplugged when you put it in 1-2? Does it buck, bind, whine, roll slowly, etc?

Could it be a solenoid? I'm not completely sure on that. You should definitely start here: http://www.transonline.com/transdigest/magazines/1997-10/Shift%20Pointers/index.html

Post your results. It'll be the best place to start.
 
If it's not shifting manually with the TCU unplugged, its not a solenoid. Maybe a flush and refill with Dex3. is in order.

I read somewhere that when the tranny shifts from 1 to 2 or 2 to 1, it was solenoid activated. How does it change if not with the solenoid?
 
With the TCU unplugged, you should be getting 1st gear with the shifter in (1-2), 3rd in (3), and 4th in (D). If you're not then its likely a problem in the valve body. It could be a solenoid is hanging up, but usually they fail electrically and just don't activate.
 
With the TCU unplugged it will start out in second gear when cold. When the vehicle is warmed up it will pass the manual shift test just fine. It will go from 1st gear to third to fourth just like it is supposed to. It only fails the manual shift test when cold.

Weird...
 
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