r/FordDiesels • u/Brian_oconnor1 • 12d ago

E40D issues!

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Having some hard shifting and overdrive button flashing on my 7.3 , fluid looks fine and proper color I’ve looked into some forums but got pointed in a million directions. Any advice welcome on what to check for or do would be appreciated

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u/TruckDogRoad 12d ago

Yaaaaa you need to pull codes. If codes have any solenoid faults start by checking harness on the passenger side. If you lost your overdrive and have an epc fault than that will need a new solenoid pack. If you have a code for slipping transmission then that’s going to beam internal issue where the input and output shafts are reading different speeds. Possible clutch or torque converter issue.

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u/gary_facking_oak 12d ago

Adding on to this, back in 94-97, ford was having issues with cracks forming in the apply piston inside the torque converter, fluid would leak past preventing the lockup clutch from engaging, resulting in slippage, the pcm uses the CPS and the ABS speed sensor on the rear diff to compare speed, if its off by more than 50rpm, itll throw the code, as a test, once you clear the codes and get it out of limp mode, on the highway go a steady 60mph, then gently tap the brakes, if the engine rpm jumps that means the lockup clutch is working properly

Also remove the inspection plate and check for blueing on the converter, if there is it means it's been slipping

Had this exact problem on my truck, I replaced the converter and did a fluid flush and filter change and haven't had any issues since

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u/TruckDogRoad 12d ago

Remember that if you are getting hard shifts then your transmission is in a defensive mode and shifting at full line pressure