My 2005 mustang gt automatic has a very strange problem… The reverse only works sometimes. When I put it from park to reverse I don’t feel any travel or feedback/click you get when shifting between gears. It kinda just slides from park to reverse without resistance and don’t feel the gear click or “lock” into place…but then will go to N D 1 2 and 3 with a distinct “click” and lock and has resistance when switching in between each gear. I can feel the “click” when going from N to R but not P to R. The transmission has 90k miles on it. I have replaced the entire shifter and this did nothing. All the forward gears work perfectly. No slipping, hesitating or noises. No OD light flashing and no check engine light or problems switching between other gears. When in park it stays parked, when in neutral it’s in neutral and when in D or 1 2 or 3 it goes forward. It’s only reverse that has any issue. Fluid and filter were changed 20k miles ago. Sometimes the car will go into reverse and sometimes it won’t. When it does decide to work it does it perfectly. No slamming into reverse, no delay - it will instantly go into reverse, and no rough shift or clunk. When it decides to not work, I’ll put it in reverse and it’s like the cars in neutral. The engine will rev but the car won’t move. What could this be
Sounds like the shifter cable to the transmission is not adjusted correctly. It is close, but not close enough. There is an adjustment under the car on the input shaft going into the trans.
This shouldn’t be a super expensive thing to do if i take it to a shop right? Doesn’t involve pulling out the transmission?
It shouldn’t be, assuming it is just the shift cable needing adjustment. I don’t think anything gets removed.
A remanufactured transmission is $3400. Did you resolve the range sensor malfunction?
No, done from below with everything in place.
I posted the service procedure for adjusting the cable on your other post about failing MD inspection. Didn’t you read it? If you can get undercar access it is an easy adjustment.
I took it to a transmission shop and they told me the shift cable was fine and that i need a new transmission. Definitely going to get a 2nd opinion
That is the wise thing to do.
Because if the reverse gear was broken it wouldn’t work sometimes. It would either work 100% of the time or not at all
You would think so.
How has the transmission been maintained? Meaning, have you changed the fluid regularly?
At 16 years, it wouldn’t surprised me much if the transmission needed some work. But regular fluid changes help with prolonging the life.
Got here too late to tell you not to take it to a chain transmission shop. 
Lemme guess, you took it to AAMCO? That stands for All Automatics Must Come Out, y’know…
Find an independent transmission shop with good reviews and take it there.
Reverse gear is hydraulically actuated, if the reverse servo piston seals are leaking there can be intermittent operation.
Thanks for the advice and insight everyone! For anyone that actually cares (probably no one) i found a pattern to get it to work.
Sometimes reverse will work right away and will not have any problem. In the scenario where it doesn’t shift into reverse right away, I put it in reverse and have to wait EXACTLY 15 seconds every time it doesn’t engage right away. The car will then go into reverse (very smoothly i might add, no clunk or slam into gear).
So basically, reverse works all the time now and the only 2 scenarios are: putting it in reverse and having it work immediately OR putting it in reverse, feeling it didn’t engage, and then wait exactly 15 seconds before it successfully goes into reverse. What could cause the transmission to do this?
I would try another fluid change, like chicken soup, “it couldn’t hurt”.
I am not a mechanic. Just suspect the valve body is gummed up. If the fluid change doesn’t help, perhaps a valve body and solenoid pack may be necessary.
Refer to Nevada’s post, just prior to your last post.
I want to second the recommendation that you seek an independent trans shop that has been in business for at least 3 or 4 years. If they tell you that you need to have the trans overhauled, they are probably right.
Lets see , the transmission could be as old as this 2005 and may not have had proper service or it could be just wore out .
But why exactly 15 seconds everytime? If it were bands or gears worn out, yes reverse could work intermittently and although there could be a delay in shifting, it seems very unlikely the delay would be the exact same amount of time everytime.
This makes me believe it could be a solenoid or electronics issue…any thoughts?
My best guess is that the tired, ailing transmission is taking that long to build-up sufficient hydraulic pressure.