Code 648

[bren7176]

I have a 1995 Explorer the OD light is flashing and I retrieve code 648 incorrect gear ratio-fourth gear. Has anyone had this problem before and what did you do fix this ..Any and all help would be welcome

thanks

Brendan:exp:

 

[BrooklynBay]

Try to adjust the band first. If you can't adjust it, then it might be broken.

 

[MrShorty]

I'm not real familiar with the 4R55E, but here's what I can say.

Your 4R55E has speed sensors on the input and output shafts of the transmission. The computer "knows" what the gear ratio of each gear should be, so it know what the relative readings of those two sensors should be. It sets that code when it gets the "wrong" reading from one of those two sensors.

1st question I would ask: Is it actually shifting into 4th gear or not? If it is going into 4th gear as it should, then the problem is likely in the sensor circuits. If the computer is commanding it to shift into 4th gear, but the transmission isn't responding, then there's some condition (such as a maladjusted or broken band as suggested by BrooklynBay) in the transmission that is preventing it from responding to the computer's commands.

 

[bren7176]

Fixed I hope

Well I adjusted the OD band today and took off all the sensor connectors and cleaned them and put back on took the EX for test drive. AS of right now no more flashing OD light one of the 2 thing may have fixed hopefully . Thanks for the feedback and suggestions . Seems to be shifting just fine..

thanks

Brendan