Something Amiss with Planetary System
You may remember back in the early days of the 41TE transmission (A604), the sun gear was known to shear off the shell. The result would be no reverse; it would take off in 1st gear but when it shifted into 2nd it would neutralize. With 2nd gear being failsafe, it would default to a neutral gear. The vehicle would then have no movement both forward and reverse. Once the ignition was cycled off to on, you could once again take off in 1st and shift into a no-move condition.
It’s the Little Things
The phrase, “It’s the little things,” is often times pared with “that count” or “will get you.” Both are true when it comes to a loss of reverse after rebuilding a 4F27E. It is easy to overlook the little things that count and it will be the little thing that gets you.
A Little Solder Does the Trick
A 2006 Mazda 3 with a 2.3L engine using a front-wheel-drive five-speed automatic transmission (FS5A-EL known as the FNR5 in Ford) comes into Bebes Transmitech shop in Puerto Rico. The A/T warning lamp is illuminated so codes were immediately checked. Only P0791 was stored in memory. It was logged and cleared before going on a road test where the code set immediately after take off.