Normally the flashing OD light when pulling a grade is telling you that the torque converter is slipping and not able to lock like it is supposed too.
When you checked codes was your scan tool able to pull transmission codes? Unfortunately they are different so we need to make sure it is able to do that as I suspect you have a code like a P0733 which is for the torque converter clutch solenoid. Basically this is monitoring the input and output speed of the transmission so that it can tell if the converter is slipping.
Let's stop by a parts store and see if they can pull other codes that will point us in this direction.
If not, we are going to need to use a scan tool that will tell us what the input and output speed sensors are reading. Basically the input speed is engine speed but we need to see what the output speed is when the torque converter is locked up.
Let's start with this and go from there. Thanks
Friday, March 12th, 2021 AT 2:13 PM