Randomly "bucks' Shifting into Reverse...2007

[cbeigle54]

I have a 2007 Fusion, admittedly a 14 year old car. Now ocassionally, when I shift into reverse, it will 'buck' twice, and

then it's fine. At other times, it smoothly shifts. What causes the random bucking? Thanks, in advance.

[shadowcast]

You need to change the tranny fluid soon.....before you can't back up anymore!!!

[nanookvd]

Hard to diagnose the vehicle without knowing its maintenance history, transmission fluid level, 2.3L or 3.0L, etc.  Has either the orange wrench or check engine lights illuminated?

 

I had this happen to one of my vehicles 2x with the orange wrench light illuminated.  Both times, the TCM (Transmission Control Module) by the brake pedal had to be replaced which solved the problem.  1st time, I fixed on my own replacing the entire valve body and sourcing a used TCM on ebay.  Second time, through a dealer since the car was out of state.  My speculation is that a weak battery and/or short of one of the solenoid valves in the transmission valve body takes out the TCM causing hard and erratic shifting, including reverse.  Be prepared for the following course of action at the Dealer as they have to follow proper troubleshooting procedures:

 

1. ~ $ 450 for initial diagnosis and verification of wiring/solenoid function (pin test).

2. ~ $ 600  to replace one of the solenoids in the transmission valve body which involves dropping the transmission pan, changing the solenoid, filter, & new fluid.  

3. ~ $ 1,100 if above doesn't solve the problem and they replace the TCM.  I negotiated this down to cost ~ $600 since 1 & 2 didn't solve the problem.

 

Again, this was my experience and may not be applicable to yours.  Beware that a transmission shop's first recommendation will be to replace the transmission for about $4k.  The cars are very solid mechanically when taken care of.  The electronics are the weak link and can make it seem you have a mechanical issue.

 

Best of luck