4r100 PTO issues
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Cross-Country
Joined: Sep 2004
Posts: 63
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From: langley, british columbia
4r100 PTO issues
I have a 2001 F550 7.3 automatic that has a PTO to run a hydraulic pump for a small Hiab crane.
it has a Ford PTO/idle control that appears to be working as it should. I press the button to turn the PTO on and the light stays on steady. I can hear the PTO come on for about 1 second. The O/D off light also comes on as it should and turns off when the PTO turns off. My scanner shows that the temp sensor is reading normal and the line pressure bumps up to 70 PSI as soon as the PTO comes on and then drops back down instantly as soon as the PTO turns off.
My research leads me to believe the issues is with the Ford PCM. I think it is seeing something from a sensor that it doesn't like. What sensors/parameters are involved with the PCM keeping the PTO turned on?
This PTO has worked problem free for the past 4 years I have owned this truck. It is set up to run at mormal ifle speed with a maximum of 1100 RPM. At 1100 RPM the PTO turns off. The PTO controller keeps the PTO indicator light on solid until I raise the idle over 1100 as it did before. The transmission fluid looks good and the level is within range on the dipstick. I did add a few quarts just to make sure that wasn't the issue.
it has a Ford PTO/idle control that appears to be working as it should. I press the button to turn the PTO on and the light stays on steady. I can hear the PTO come on for about 1 second. The O/D off light also comes on as it should and turns off when the PTO turns off. My scanner shows that the temp sensor is reading normal and the line pressure bumps up to 70 PSI as soon as the PTO comes on and then drops back down instantly as soon as the PTO turns off.
My research leads me to believe the issues is with the Ford PCM. I think it is seeing something from a sensor that it doesn't like. What sensors/parameters are involved with the PCM keeping the PTO turned on?
This PTO has worked problem free for the past 4 years I have owned this truck. It is set up to run at mormal ifle speed with a maximum of 1100 RPM. At 1100 RPM the PTO turns off. The PTO controller keeps the PTO indicator light on solid until I raise the idle over 1100 as it did before. The transmission fluid looks good and the level is within range on the dipstick. I did add a few quarts just to make sure that wasn't the issue.
FTE Chapter Leader
Joined: Jan 2005
Posts: 13,106
Likes: 4,714
From: Henderson, NV
I have absolutely no knowledge of PTO operation but here is a bump to get your thread back to the top.
Perhaps @Mark Kovalsky might know.
Perhaps @Mark Kovalsky might know.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,714
Likes: 2,639
From: SE Florida
I do not know what the PCM uses to turn the PTO off.
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Cross-Country
Joined: Sep 2004
Posts: 63
Likes: 0
From: langley, british columbia
is there a pressure sensor in the valve body or somewhere else? I am thinking that it is sensing low pressure and cutting out to protect the coast clutch. The coast clutch appears to be working properly seeing as I do get engine braking in manual 2nd.
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,919
From: Reed Point, MT
There is no pressure sensor inside of the transmission.
I think you need to look at enable criteria on the datastream next. The PCM seems as though it sees something it doesn't like (park brake, brake on/off, brake pressure, etc.).
I think you need to look at enable criteria on the datastream next. The PCM seems as though it sees something it doesn't like (park brake, brake on/off, brake pressure, etc.).
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Joined: Dec 2011
Posts: 13,286
Likes: 6,058
I have a 2001 F550 7.3 automatic that has a PTO to run a hydraulic pump for a small Hiab crane.
it has a Ford PTO/idle control that appears to be working as it should. I press the button to turn the PTO on and the light stays on steady. I can hear the PTO come on for about 1 second. The O/D off light also comes on as it should and turns off when the PTO turns off. My scanner shows that the temp sensor is reading normal and the line pressure bumps up to 70 PSI as soon as the PTO comes on and then drops back down instantly as soon as the PTO turns off.
My research leads me to believe the issues is with the Ford PCM. I think it is seeing something from a sensor that it doesn't like. What sensors/parameters are involved with the PCM keeping the PTO turned on?
This PTO has worked problem free for the past 4 years I have owned this truck. It is set up to run at mormal ifle speed with a maximum of 1100 RPM. At 1100 RPM the PTO turns off. The PTO controller keeps the PTO indicator light on solid until I raise the idle over 1100 as it did before. The transmission fluid looks good and the level is within range on the dipstick. I did add a few quarts just to make sure that wasn't the issue.
it has a Ford PTO/idle control that appears to be working as it should. I press the button to turn the PTO on and the light stays on steady. I can hear the PTO come on for about 1 second. The O/D off light also comes on as it should and turns off when the PTO turns off. My scanner shows that the temp sensor is reading normal and the line pressure bumps up to 70 PSI as soon as the PTO comes on and then drops back down instantly as soon as the PTO turns off.
My research leads me to believe the issues is with the Ford PCM. I think it is seeing something from a sensor that it doesn't like. What sensors/parameters are involved with the PCM keeping the PTO turned on?
This PTO has worked problem free for the past 4 years I have owned this truck. It is set up to run at mormal ifle speed with a maximum of 1100 RPM. At 1100 RPM the PTO turns off. The PTO controller keeps the PTO indicator light on solid until I raise the idle over 1100 as it did before. The transmission fluid looks good and the level is within range on the dipstick. I did add a few quarts just to make sure that wasn't the issue.
There is a sensor inside of PTO equipped 4R100 transmissions that counts the teeth on the PTO gear.
According to Ford, if the vehicle batteries are disconnected, the powertrain control strategy might "forget" the PTO logic, and may not respond to commands for elevated idle. To remedy this, the sensor in the transmission needs to count the teeth on the PTO gear.
If you drive the truck for a short distance, less than a mile, that should be sufficient for the sensor to recount the teeth and prepare the strategy accordingly. If you drive the truck in first gear, the process might be faster, requiring less distance traveled.
However, keep in mind that once the ignition cycles through ON, START (CRANK), and RUN, the strategy cycle that looks for PTO only lasts a relatively short time, so don't delay after starting the truck to get moving, so that the strategy can do its thing recounting.
Repeat the drive cycle if the first time is ineffective.
The foregoing may be applicable if vehicle power to the PCM and APCM was lost (batteries disconnected).
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,919
From: Reed Point, MT
Were the batteries recently disconnected from the truck, just prior to this issue manifesting itself?
There is a sensor inside of PTO equipped 4R100 transmissions that counts the teeth on the PTO gear.
According to Ford, if the vehicle batteries are disconnected, the powertrain control strategy might "forget" the PTO logic, and may not respond to commands for elevated idle. To remedy this, the sensor in the transmission needs to count the teeth on the PTO gear.
If you drive the truck for a short distance, less than a mile, that should be sufficient for the sensor to recount the teeth and prepare the strategy accordingly. If you drive the truck in first gear, the process might be faster, requiring less distance traveled.
However, keep in mind that once the ignition cycles through ON, START (CRANK), and RUN, the strategy cycle that looks for PTO only lasts a relatively short time, so don't delay after starting the truck to get moving, so that the strategy can do its thing recounting.
Repeat the drive cycle if the first time is ineffective.
The foregoing may be applicable if vehicle power to the PCM and APCM was lost (batteries disconnected).
There is a sensor inside of PTO equipped 4R100 transmissions that counts the teeth on the PTO gear.
According to Ford, if the vehicle batteries are disconnected, the powertrain control strategy might "forget" the PTO logic, and may not respond to commands for elevated idle. To remedy this, the sensor in the transmission needs to count the teeth on the PTO gear.
If you drive the truck for a short distance, less than a mile, that should be sufficient for the sensor to recount the teeth and prepare the strategy accordingly. If you drive the truck in first gear, the process might be faster, requiring less distance traveled.
However, keep in mind that once the ignition cycles through ON, START (CRANK), and RUN, the strategy cycle that looks for PTO only lasts a relatively short time, so don't delay after starting the truck to get moving, so that the strategy can do its thing recounting.
Repeat the drive cycle if the first time is ineffective.
The foregoing may be applicable if vehicle power to the PCM and APCM was lost (batteries disconnected).
Good call!
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