94 GT auto trans randomly downshifting

[J-rod]

well just got the 5.0 last night. drove over 2 hours home with a couple stops along the way. Everything was fine.

go to take my boy to school in it this morning and I noticed as I am cruising along around 50 it sort of quickly downshifted (out of OD) and then right back into OD.

Thinking I am still sleepy I just keep going. Then it did it to me on I79 going to work. And did it several times tonight coming home.

I will be cruising along with constant throttle and it will seemingly kick out of OD and the RPM will climb. then it will go back to normal cruising.

I did a quick Google search and many people point to this as a bad NSS. I am not about to start throwing parts on it without a little more confidence that I am going to fix the issue. Though does feel like an electrical component issue.

< been out of the game 6 years and wasnt that good at the 5.0 diag before LOL.

[PaceFever79]

I'm no AOD expert, but here's a few thoughts.....



Check the AOD TV cable for proper adjustment and function. Your problem may be something else but you should start with the TV Cable. If the cable or bushings are worn you can buy them HERE

If that doesn't help, the two most likely possibilities are an overdrive band problem, or a stuck 3-4 shift valve. If the overdrive band is worn, when the transmission shifts into overdrive it will neutral out and start to rev freely, but not accelerate the vehicle. If the servo that applies the band is stuck or has badly damaged seals the symptoms will be the same.

If the 3-4 shift valve is stuck (from sitting), then the transmission will not shift into overdrive, but will not neutral out. The transmission will continue to pull in 3rd gear with no slippage. If this is your problem, replacing or rebuilding the valve body and doing a flush and fill should fix the problem. If it doesn't then the trans has other internal problems.

Just a few things I have learned, experts feel free to chime in!

[SAC81]

well just got the 5.0 last night. drove over 2 hours home with a couple stops along the way. Everything was fine.

go to take my boy to school in it this morning and I noticed as I am cruising along around 50 it sort of quickly downshifted (out of OD) and then right back into OD.

Thinking I am still sleepy I just keep going. Then it did it to me on I79 going to work. And did it several times tonight coming home.

I will be cruising along with constant throttle and it will seemingly kick out of OD and the RPM will climb. then it will go back to normal cruising.

I did a quick Google search and many people point to this as a bad NSS. I am not about to start throwing parts on it without a little more confidence that I am going to fix the issue. Though does feel like an electrical component issue.

< been out of the game 6 years and wasnt that good at the 5.0 diag before LOL.

Are you sure it downshifted? Sounds like the converter is locking/unlocking. Pretty common AODE failure. I blew one up years ago that was one of the early symptoms.

Cruising in OD, the converter is going to be locked - when it unlocks, RPMs climb pretty quick, then drop when it locks again.
Sounds like that's what's happening with your situation.

[J-rod]

def seems to be downshifting. the RPMS do not climb freely as if it was going into N. It starts to pull as the RPM's increase, thus making me believe it is downshifting.

[SAC81]

That's what happens when the converter unlocks, too.

[J-rod]

fluid is at the proper level and clean (red) not burnt.

today I was driving through town and back roads so I turned the OD off. It still downshifted on me randomly. with the OD turned off keeping it from going into OD and the TC locking to begin with...wouldn't this rule out a TC issue?

I still see a lot of chatter on Google/Forums about the MLP/NSS causing this issue. I have a hard time believing the NSS would cause a shifting issue, but I am still trying to comprehend.

[J-rod]

I have ruled out the TV Cable. I took the slack out of it today. went for a drive and had same issue.

will try the NSS next. $40 try.

[PaceFever79]

I'm surprised the TV cable wasn't causing it..

What happens after it has improperly downshifted to 2nd gear? Does it up shift normally back into 3rd? What do you have to do to get it to shift back into 3rd? or does it just stay stuck in 2nd gear for a while?

[J-rod]

when it downshifts it will go back into 3-4th gear after a few seconds. It seems like I can blurp the throttle when it downshifts and sometimes it will return to 3-4 gear. but usually it will just shift back into the proper gear after a few seconds. I hate it on the interstate....cruising at 2k and then bam...3k for a few seconds. So until I get it fixed I will be sticking to back roads or driving the JK.

[PaceFever79]

Something else to check is the shifter linkage bushing. If they get worn the shifter may not put the trans completely into gear, which can cause erratic shifting. Especially if you like to manually select your gears. When you go from 2nd to Drive if the sloppy shifter doesn't push the gear selector lever all the way into Drive, it can suddenly shift back into 2nd while cruising. If just rowing the shifter makes your transmission come out of 2nd gear and go into Drive again then it might be a shifter problem.

[J-rod]

Thanks.

I will check that out when I finally get the stang up in the air

Linkage here right: http://www.dormanproducts.com/p-5403...Linkage%20Clip

[PaceFever79]

That is just the retainer clip

Jack the car up, put it on jack stands
Remove the shifter cable from the lever on the side of the transmission
Inspect the cable and bushing for damage or excessive wear (replace as needed)
Pull the shifter handle back 3 clicks into Drive (OD) position
Crawl under and move the trans lever 3 clicks from Park (to Drive)
Adjust the shifter cable length to match the trans lever position then attach it

[J-rod]

Well I hesitate to say it is "fixed" but I put a new NSS on yesterday at lunch. So far 70 miles logged on the car and shifting fine. keeping fingers crossed.