Robert Rhein Posted June 17, 2016 Share Posted June 17, 2016 Hello Moses, I see by your writings that you are very well versed with transmissions including the 46RE. I hope you can provide me some advice. My transmission was working pretty well when all of a sudden when the overdrive engages (at and above 25mph) it slows the vehicle (like coming to a fast stop) similar to heavy braking. The transmission works fine with overdrive switched 'off' but if switched 'on' at or above 25mph it consistently tries to stop the vehicle. Any suggestions? Thanks for sharing your knowledge, Bob Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted June 17, 2016 Administrators Share Posted June 17, 2016 Hi, Bob...Thanks for joining us at the forums! Do you have the NP/NV249 transfer case with a viscous coupler? If so, the viscous coupler is a known failure part that can cause a variety of drivetrain quirks, including binding of the drive system. I would check this first, the label on the transfer case indicates whether you have an NV242 or NV249 transfer case. There are specific tests for the viscous coupler. If the transmission is the problem and not the transfer case viscous coupler, your symptoms could be the direct clutch in the 46RE not disengaging as the overdrive clutch (4th gear) shift takes place. The direct clutch applies in all of the 46RE shift ranges except overdrive. If the direct clutch stays engaged when it should be releasing you could have a severe binding that would act like the "brakes are on". "Something" is preventing the direct clutch from disengaging during the shift to 4th/overdrive. As a matter of routine, I would do a band adjustment and fluid/filter change, inspecting the solenoid connections while the oil pan is down. Beyond this chance of a light fix, I would check fluid pressures and the pressure relief functions at the pressure test ports with the transmission in gear (performed safely on a hoist following the factory steps). Also, a DRB or equivalent scan tool test might turn up a transmission trouble code. A scan like this could be worth trying. We can pursue other possibilities once there are more test findings... Moses Quote Link to comment Share on other sites More sharing options...
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