Overdrive problem
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New User
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Overdrive problem
I have a 2000 F-150 4x4 with a 5.4 engine. On two different occasions, I have been driving down the highway about 70 miles an hour down a slight grade in OD. When I let off the gas to coast a little the truck will downshift. press on the gas again, the truck goes back into OD. I do this a couple of times and then it wont do it again. Any ideas as to what might be happening. Truck has 82,000 miles on it. I am the only owner. Transmission fliud changed a year ago. Thanks.
Lead Driver
Joined: Sep 2006
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Not saying you don't have something going on but the system will drop OD in rsponse to a sudden closing of the throttle and brake signal.
All the electirc transmissions from as far back as 1984 will do this.
The intent by design is if you need to 'panic brake', the trans is taken out of OD and unlocked so the motor does not add to the stopping distance.
At this point the drive train becomes 'soft' from the fluid slip in the converter so the motor will not add it's rpm momentum to the situation..
You can see this feature work by suddenly lifting, touching the brake pedal then put throttle back on.
Watch the Tach RPM rise about 300 RPM then drop again as the converter lockup come back and OD is upshifted to.
The 'relockup' is due to a timer in software that does this unless the brake signal is present
After this happens the RPM won't respond much the throttle due to the lockup but only rise slowly as the road speed goes up.
As said above, you might have something else going on.
Good luck.
All the electirc transmissions from as far back as 1984 will do this.
The intent by design is if you need to 'panic brake', the trans is taken out of OD and unlocked so the motor does not add to the stopping distance.
At this point the drive train becomes 'soft' from the fluid slip in the converter so the motor will not add it's rpm momentum to the situation..
You can see this feature work by suddenly lifting, touching the brake pedal then put throttle back on.
Watch the Tach RPM rise about 300 RPM then drop again as the converter lockup come back and OD is upshifted to.
The 'relockup' is due to a timer in software that does this unless the brake signal is present
After this happens the RPM won't respond much the throttle due to the lockup but only rise slowly as the road speed goes up.
As said above, you might have something else going on.
Good luck.
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New User
Joined: Jul 2011
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Thanks Bluegrass...Do you think I should take truck to a transmission mechanic? Can they see any problems in the transmission on a diagnostic machine? It could be like you said or I may have something going on.
Lead Driver
Joined: Sep 2006
Posts: 7,907
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Dose it continue to happen differently that I discribed?
If yes, a good shop on these should have an idea what the issue is.
Codes are electrical faults detected.
Mechanical faults by feel and operating observations.
Good luck.
If yes, a good shop on these should have an idea what the issue is.
Codes are electrical faults detected.
Mechanical faults by feel and operating observations.
Good luck.
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Joined: Mar 2013
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