Defective speedo
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Senior User
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From: SW Washington, USA
Defective speedo
1992 F-150 4x4
My instrument panel is electronic and only works periodically, when it doesn't sometimes my tranny doesn't shift correctly. I was told that my speed sensor is bad. The problem is I can't get the right one because it is on my rearend and the Ford dealer parts guy says no that is my abs sensor well it must be the speed sensor because I don't have one on my transfer case. The BIG problem is no one can get me the part if all the parts list say it is on the transfer case. I am at least the 4th owner and don't know anything about it other than I had to replace my engine a year ago. I even took them the part at Napa auto parts as well as Schucks auto parts and they all say go to dealer and he just scratches his head.
Kallie
My instrument panel is electronic and only works periodically, when it doesn't sometimes my tranny doesn't shift correctly. I was told that my speed sensor is bad. The problem is I can't get the right one because it is on my rearend and the Ford dealer parts guy says no that is my abs sensor well it must be the speed sensor because I don't have one on my transfer case. The BIG problem is no one can get me the part if all the parts list say it is on the transfer case. I am at least the 4th owner and don't know anything about it other than I had to replace my engine a year ago. I even took them the part at Napa auto parts as well as Schucks auto parts and they all say go to dealer and he just scratches his head.
Kallie
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From: New Jersey
The speed sensor is on the differential. It's wired to the RABS system, which in turn buffers the signal and passes it to the PSOM module which is mounted on the back of your speedometer. The PSOM in turn moves the speedo needle, clicks up the odometer, and also does the "divide by" function which allows you to run larger, or smaller tires with a correct speedo/odo reading. Then, it buffers the signal again and feeds it to the EEC (EFI computer) which also manages shifting your transmission.
If it is the speed sensor, it's raybestos part number #ABS530000 and should be about $30 or thereabouts.
If it is the speed sensor, it's raybestos part number #ABS530000 and should be about $30 or thereabouts.
Fleet Owner
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From: Easton,Ks
Originally Posted by alz
That sensor does both. It is used as a vehicle speed sensor(vss) and an ABS, or RABS in the case of the F150s. What you're looking for sits at the top of the rear differential.
Kallie
Just buy the abs sensor from the Ford dealer parts guy.
Also this problem you are having could also be a bad PSOM or wiring (plugs).
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From: SW Washington, USA
I was wrong it doesn't work anymore. I don't know why it just stopped. Any ideas? What is the PSOM and do you mean tranny wiring?
Kallie
Kallie
Last edited by Kallie; Dec 9, 2006 at 03:01 AM. Reason: forgot to add something
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From: Easton,Ks
Originally Posted by Kallie
What is the PSOM and do you mean tranny wiring?
Kallie
Kallie
The PSOM (Programmable Speedometer/Odometer Module) is a small computer that is mounted inside of your cluster and drives the speedometer and odometer. It gets speedometer information from the VSS on the rear end carrier from an excitor ring next to the ring gear in the rear differential. Because the ring gear (and the excitor ring) turns at basically the same speed as the tire regardless of the rear end ratio, the speedometer only needs to be recalibrated to account for changes in tire size.
As far as I know all PSOMs are the same on all Ford Trucks from 1992 to 1996 and a 1992 will fit in a 1996 cluster and work OK.
The PSOM was only used in Ford Trucks, Broncos and Vans from 1992 to 1996.
The PSOM also keeps track of your mileage and tire size.
A PSOM can be reprogrammed six times for tire size changes.
Ford will not sell you a PSOM but will install one for about $450.00.
Here is a photo of a PSOM:
http://i54.photobucket.com/albums/g91/subford/DSC02313.jpg
Last edited by subford; Dec 9, 2006 at 06:29 AM.
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From: Easton,Ks
Originally Posted by Kallie
I forgot to say I already replaced my computer $220
Kallie
Kallie
The problem you were describing has nothing to do with the computer.
I hope you kept the old one.
You may also have a wiring problem from the rear carrier to the PSOM or a power problem from the fuses to the PSOM as the PSOM usually does not work off and on.
Also check the flat ribbon cable from the PSOM to the odometer, as sometimes the transmission range pointer will cut into this cable.
Last edited by subford; Dec 9, 2006 at 06:35 AM.
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