Speedometer
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Junior User
Joined: Apr 2013
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Speedometer
Hey guys. Well i have noticed now that when my truck is cold, like when i start it in the morning after a really cold night my speedometer reads like 20 mph over what i am actually going. Like the other day i stopped and started rolling and it said i was going 15 and i was going like 1 no lie. Does anyone know what it would be. And by really cold i mean like 16.
Lead Driver
Joined: Mar 2006
Posts: 6,259
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From: IL
Well not knowing the variables like the year of truck, size tires or any other info, here's a link to recalibrate your F series truck from 92 - 96. Hope it helps.
HOW TO RECALIBRATE THE SPEEDOMETER ON 92-96 FORD F-SERIES AND BRONCO .: Articles
HOW TO RECALIBRATE THE SPEEDOMETER ON 92-96 FORD F-SERIES AND BRONCO .: Articles
Senior User
Joined: Oct 2013
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It doesn't sound like a calibration problem. It sounds more like something is cracked or poorly soldered and the cold lets it separate, causing bad signals to or wrong calculations in the PSOM -- especially if it starts working right once the truck warms up.
I would probably go for the low-hanging fruit and pull the PSOM board from the speedometer then give it a good inspection under a magnifier looking for fractured solder joints. The VSS sensor and tone ring will warm up in operation; those would probably be my next targets. There was also a service bulletin for the VSS that might affect this particular truck. It was for a wavering speedo needle due to a slightly less than perfect VSS signal. I can see that affecting your speedo, so it might be worth verifying the SB has been performed on your truck.
I would probably go for the low-hanging fruit and pull the PSOM board from the speedometer then give it a good inspection under a magnifier looking for fractured solder joints. The VSS sensor and tone ring will warm up in operation; those would probably be my next targets. There was also a service bulletin for the VSS that might affect this particular truck. It was for a wavering speedo needle due to a slightly less than perfect VSS signal. I can see that affecting your speedo, so it might be worth verifying the SB has been performed on your truck.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
Without knowing the year of the truck everything suggested is pure conjecture. The troubleshooting and resolution path is completely different for a cable driven speed/odometer ('91 and prior) versus an electronic ('92 and newer) speed/odometer.
Cargo Master
Joined: Mar 2007
Posts: 2,935
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From: Arcadia, Fla
Its a mechanical speedo for a 91, probable lube inside the speedo is hard when its cold. Best to take the cluster out and carefully clean the speedometer(electronics cleaner) and relube it with silicone spray. That's what I have done in the past with my speedometers when they act up like that.
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Junior User
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Ok so how do i get to the speedometer to relube it. Sorry if that is a stupid question i am only 16.
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Senior User
Joined: May 2005
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From: Carthage, MO
Then take the cluster apart--some pretty small screws to get the clear cover off. Next take the gauges out of the cluster. At last you'll be able to see the workings behind the speedometer. The whole process is easier than it sounds.
Silicone or light oil should do it. Check the magnet rotor for any dust buildup and try to clean it. They're really simple, so I'd be curious about what you find. There's not much that can go wrong with them.
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Lead Driver
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From: Sand Lake, MI
Somebody's gotta ask might as well be me,
Are you sure the rear tire isn't spinning faster than the truck is moving?
Truck cold idle tad to high spinning a rear wheel on ice/snow coupled perhaps with rear brakes not working so good these days little to far out of adjustment stop it when lightly applied?
I can see mechanical cable driven speedo failing slow yea but too fast? Had a lot of em over the years gotta say don't recall one ever doing so, plenty cold here too!
Are you sure the rear tire isn't spinning faster than the truck is moving?
Truck cold idle tad to high spinning a rear wheel on ice/snow coupled perhaps with rear brakes not working so good these days little to far out of adjustment stop it when lightly applied?
I can see mechanical cable driven speedo failing slow yea but too fast? Had a lot of em over the years gotta say don't recall one ever doing so, plenty cold here too!
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Junior User
Joined: Apr 2013
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Somebody's gotta ask might as well be me,
Are you sure the rear tire isn't spinning faster than the truck is moving?
Truck cold idle tad to high spinning a rear wheel on ice/snow coupled perhaps with rear brakes not working so good these days little to far out of adjustment stop it when lightly applied?
I can see mechanical cable driven speedo failing slow yea but too fast? Had a lot of em over the years gotta say don't recall one ever doing so, plenty cold here too!
Are you sure the rear tire isn't spinning faster than the truck is moving?
Truck cold idle tad to high spinning a rear wheel on ice/snow coupled perhaps with rear brakes not working so good these days little to far out of adjustment stop it when lightly applied?
I can see mechanical cable driven speedo failing slow yea but too fast? Had a lot of em over the years gotta say don't recall one ever doing so, plenty cold here too!
Cargo Master
Joined: Mar 2007
Posts: 2,935
Likes: 34
From: Arcadia, Fla
There's probly dirt/grease on the magnet bar hitting the meter cup causing it to show high, next possablity is the clock spring is broke or weak, that will cause the needle to read higher than/not return to 0mph. At that point, time to find another speedo head.
Most likely it needs a good cleaning and relube.
Just be careful on disconnecting the speedo cable from the cluster, its a PITA to get your hands back there to press the release pin on the cable with out dammaging the wire board on the back of the cluster.
Most likely it needs a good cleaning and relube.
Just be careful on disconnecting the speedo cable from the cluster, its a PITA to get your hands back there to press the release pin on the cable with out dammaging the wire board on the back of the cluster.
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