ATX neutrals out at stop

[Jon Klein]

I have a 95 ATX with 123,000mi. When the car gets up to operating temperature it intermittently will neutral out at COMPLETE STOPS ONLY. When this occurs, as I go to accelerate the trans slams into first and then is completely normal. If I manually shift into neutral then back to drive BEFORE trying to accelerate everything seems normal. Also, if I manually down shift through the gears all the way down to first, then come to a stop the trans DOES NOT neutral out. Sorry for the long post, I figured all the information I could give you guys would help us get to the bottom of this problem. Thank you in advance for any insight you can offer. Happy Trails.

 

[Mr Anonymous]

Probably a bad forward clutch piston.

 

[Jon Klein]

Thank you for the quick reply. Is that usually an expensive fix? Does the entire transmission need to be removed and disassembled to replace the piston? Also, should I stop driving it? I use the car as my daily transportation to work. But I don't want to smoke the whole thing if its something simple right now. Thanks again.

 

[projectSHO89]

It's going to need a rebuild anyway to fix it if the drum is cracked.

Steve

 

[Jon Klein]

I just went out to the car and pulled the battery terminals to reset the computer. Now the car doesn't have any issues. I did this once before when the trans would start in Second gear unless I manually put it in first. It fixed that problem too and it never came back. Any ideas?

 

[Jon Klein]

Ok so I just got done driving the car. If OD is OFF the trans never does anything out of the ordinary. Also, the problem is definitely heat related. It only happens at operating temperature.

 

[projectSHO89]

If it's due to a cracked drum, the fluid thins out when it gets hot. The thinner viscosity fluid then leaks through the cracks in the forward clutch drum under pressure.

There's a chance that you have a flaky TR sensor. Running the Transaxle Drive Cycle test per the factory service manual would be the best place to start.

3.2L SHO Only

1. Record and then erase Quick Test codes.

2. Warm engine to normal operating temperature.

3. Make sure transmission fluid level is correct.

4. With transaxle in DRIVE, press TCS (LED lamp should illuminate) and moderately accelerate from stop to 64 km/h (40 mph). This allows transaxle to shift into third gear. Hold speed and throttle open steady for a minimum of 15 seconds (30 seconds above 4000 ft).

5. Press TCS (LED lamp should turn off) and accelerate from 64 km/h (40 mph) to 80 km/h (50 mph). This allows transaxle to shift into fourth gear. Hold speed and throttle position steady for a minimum of 15 seconds.

6. With transaxle in fourth gear and maintaining steady speed and throttle opening, lightly apply and release brake (to operate stoplamps). Then hold speed and throttle steady for an additional five seconds minimum.

7. Brake to a stop and remain stopped for a minimum of 20 seconds.

8. Repeat Steps 4 through 7 at least five times.

9. Perform Quick Test and record continuous codes.

Post whatever codes you get, both before and after, if any.

Steve

 

[Jon Klein]

Thank you so much for the info! I'll do that when I get home tonight. Hopefully we get some good results. Thanks again.

 

[Jon Klein]

Sorry I forgot to ask this earlier, by quick test you mean KOEO right?

 

[Jon Klein]

Codes

Ok so I ran the KOEO test and came up with codes 522, 335, 176, 177, 543, and 634.

 

[projectSHO89]

522 indicates the computer didn't see that the transmission was in park or neutral during the KOEO test. Perhaps there is an issue with the TR sensor which might explain the transmission dropping out of gear.

634 is another TR sensor fault code.

I'd suggest replacing the TR sensor. They're not expensive (about $62 for a Motorcraft SW5198 from O'Reilly's, much less for an aftermarket) and would be a recommended replacement anyway should a rebuild be called for.

Steve