My son was driving on the freeway when the transmission gave a fault message and went into limp mode. He pulled over and restarted the truck. The transmission was shifting erratic from start and would seem like it was stuck eventually staying in third. I disconnected the battery for 24hrs but when I turned it on the problem remained. Would appreciate any help.

Additional details;
have it for a year but tranny never worked properly. Previous owner never fixed pan leak and was ran low until I bought it.

I changed the fluid and and added a new pan. Worked fine for about a month but would start slipping out of 6th when on a load.

Now on it slips out of 5th and 6th when a load is given. I have had to shift it manually down to 4th during slight grade.

I checked the the fluid and it seemed it was over filled when at temp. After wards it seemed as if it would work in automatic. I suspect that it needed new solenoids as old ones may be going.

No this problem has me stumped. I don’t have a scanner just a pocket code reader. Only codes I get are p0735, p0736 which is when it slips and goes into limp mode. Usually restarting the truck fixes it.

 

Those codes refer to 5th and 6th gears so those solenoids are faulty, time to rebuild the valve body with new solenoids and seals.

 

What would cause the fault message? Could it be the transmission controller that is causing the transmission to act crazy?

 

Any failure or out of spec signal will produce the fault message, then you need to interpret the codes to find which component/s have failed.