95 f150 speedometer problem
New User
Joined: May 2014
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Okay, that's kind of cool in an off beat way. But I'm sure I got your email but honestly I don't know how to get back to it, this forum kind of looks like a mess on my work computer. But could the issue also be the fact that I am running 265 75 16??
I also did the test again and yes it displayed a backwards six with some digits. I pressed the button again and it says I apparently have 377,777 miles on my truck as opposed to 210,000 lol.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
One of those miles should be the trip miles.
No the wrong tire size will not cause your problem. It will not show the right speed amd the odometer will give a different mileage than what the truck has.
The 984CAL is what the factory set the PSOM to when it was new and the new truck should have had the LT235/85R16 E Highway tire with 656 Revs per mile on it when it was bough.
The 265 75 16 is not on the Ford chart so the CAL would have to be calculated before changing the CAL. You also have to go to the tire maker and find the revs per mile for their tire to do the calculation.
No the wrong tire size will not cause your problem. It will not show the right speed amd the odometer will give a different mileage than what the truck has.
The 984CAL is what the factory set the PSOM to when it was new and the new truck should have had the LT235/85R16 E Highway tire with 656 Revs per mile on it when it was bough.
The 265 75 16 is not on the Ford chart so the CAL would have to be calculated before changing the CAL. You also have to go to the tire maker and find the revs per mile for their tire to do the calculation.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
To me it sounds like you have bad wiring under the dash. An open wire from the VSS to the PSOM and a loose power wire that make the odometer flicker.
If it was mine I would inject 667Hz into the test plug under the hood and see if the pointer points to 30mph. Then turn the key off and back on to see if the odometer was updating.
I am sorry but I do not know any other way to test the PSOM, odometer and speedometer head under your circumstances. I do not think replacing the PSOM and speedometer head will tell you anything. I think a replacement would do the same thing from the test you did on it.
By any remote chance do you have a parking brake mounted on the back of the transmission with a VSS plugged into the side of it? That is the only other thing I can come up with. As that is the way Ford did the VSS on the F53's.
If it was mine I would inject 667Hz into the test plug under the hood and see if the pointer points to 30mph. Then turn the key off and back on to see if the odometer was updating.
I am sorry but I do not know any other way to test the PSOM, odometer and speedometer head under your circumstances. I do not think replacing the PSOM and speedometer head will tell you anything. I think a replacement would do the same thing from the test you did on it.
By any remote chance do you have a parking brake mounted on the back of the transmission with a VSS plugged into the side of it? That is the only other thing I can come up with. As that is the way Ford did the VSS on the F53's.
New User
Joined: May 2014
Posts: 10
Likes: 0
To me it sounds like you have bad wiring under the dash. An open wire from the VSS to the PSOM and a loose power wire that make the odometer flicker.
If it was mine I would inject 667Hz into the test plug under the hood and see if the pointer points to 30mph. Then turn the key off and back on to see if the odometer was updating.
I am sorry but I do not know any other way to test the PSOM, odometer and speedometer head under your circumstances. I do not think replacing the PSOM and speedometer head will tell you anything. I think a replacement would do the same thing from the test you did on it.
By any remote chance do you have a parking brake mounted on the back of the transmission with a VSS plugged into the side of it? That is the only other thing I can come up with. As that is the way Ford did the VSS on the F53's.
If it was mine I would inject 667Hz into the test plug under the hood and see if the pointer points to 30mph. Then turn the key off and back on to see if the odometer was updating.
I am sorry but I do not know any other way to test the PSOM, odometer and speedometer head under your circumstances. I do not think replacing the PSOM and speedometer head will tell you anything. I think a replacement would do the same thing from the test you did on it.
By any remote chance do you have a parking brake mounted on the back of the transmission with a VSS plugged into the side of it? That is the only other thing I can come up with. As that is the way Ford did the VSS on the F53's.
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Cargo Master
Joined: Mar 2007
Posts: 2,935
Likes: 34
From: Arcadia, Fla
Sounds like either wireing uder the dash like Subford said, or could be a PSOM failing with that infamous capacitor leaking acid on the Pc board.
I 2nd the 667Hz test into the RABS test port if you have a signal generator. The other way you could test is SAFELY jack up the rear axle( both wheels off ground) and block the front wheels. Put truck in to 1st gear ONLY and let it idle. See how the PSOM reacts. Take a long stick or broom handle and start wiggling the VSS sensor connector and under hood wiring. Never get under the truck while doing this! Best to have a 2nd person ready to shut down the truck if any issues occure.
The other thing you can do, is replace the PSOM and hope that was the problem.
I 2nd the 667Hz test into the RABS test port if you have a signal generator. The other way you could test is SAFELY jack up the rear axle( both wheels off ground) and block the front wheels. Put truck in to 1st gear ONLY and let it idle. See how the PSOM reacts. Take a long stick or broom handle and start wiggling the VSS sensor connector and under hood wiring. Never get under the truck while doing this! Best to have a 2nd person ready to shut down the truck if any issues occure.
The other thing you can do, is replace the PSOM and hope that was the problem.
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