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Old 08-18-2007
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Speedo Not Reading Right

Hello. I am new to this forum. I have a question. I own a 1999 Ranger Flareside with the 2.5 Liter with the 5 speed transmission. The speedo reads about 5 to 10 miles an hour faster than what you are actually doing. What do I need to look at? The truck has about 117,000 miles. Thanks
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Old 08-18-2007
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Check your current tire size against the factory size listed on the cert label on the driver side door or jamb. A smaller than factory tire diameter will make the speedometer read faster than actual. This type error can usually be corrected with a Ford dealer tool that accesses and reflashes the GEM module.

A second common way to get speedometer error is when installing aftermarket "glow gauges" or other similar mods. The needle needs to be removed for this type of mod and it's easy to get it on wrong when reassembling. This error should be corrected by positioning the needle correctly. It requires disassembly of the cluster and trial and error adjusting using a GPS or chase vehicle to check it.
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Old 08-18-2007
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My tires are a wee bit bigger than stock. And the gauge is stock. Is there like a gear or something in the tranny that might be worn out or maybe the cable is loose or I have no idea.
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Old 08-18-2007
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If the rear end is factory stock and you put bigger tires on.. your speedo should be reading slower. Can you verify that the odometer is reading too short / too long?

There is a possibility someone changed the rearend and the new one had steeper gear in it.

I don't know about your tranny.. but mustangs w/5speeds have a little plastic gear than can be changed to correct the speedo.

Rich
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Old 08-18-2007
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Quote:
Originally Posted by cghstrojan08
Is there like a gear or something in the tranny that might be worn out or maybe the cable is loose or I have no idea.
You have an electric speedometer and there is no gear or speedo cable. The vehicle speed on 98~2000 Rangers is taken from the rear axle ABS sensor and corrected in the GEM assuming that you have RABS. Trucks with 4WABS make the speedo correction in the 4WABS Module.

Changing the axle ratio of a 98~2000 Ranger does not affect the speedometer because the ABS sensor measures ring gear RPM.
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Old 08-19-2007
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Thanks Bob. I did'nt know that.

Rich
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Old 08-19-2007
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Ya, I know it is reading faster than I am actually going. I think everything on it is stock. Is there not an adjustment somewhere? The truck does not have ABS.
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Old 08-19-2007
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Quote:
Originally Posted by cghstrojan08
The truck does not have ABS.
Yes it does. Since it is a 4-cylinder, it probably has Rear ABS (RABS) only.

Quote:
Originally Posted by cghstrojan08
Is there not an adjustment somewhere?
As I mentioned before, the speedometer is electric and the correction is done by reflashing a module using a Ford dealer tool. There is no mechanical adjustment except in the case where the needle has been installed incorrectly.
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Old 08-19-2007
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Well, it doesn't say anywhere that there is ABS but if you say so. How would I get it fixed and how much would it cost?
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Old 08-22-2007
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The autoparts store told me that there is a sensor on the tranny. I looked and there isn't one. I have been doing some research and it sounds like the sensor on the top of the rear end can get dirty or worn out. You think I should just replace it? Also, is there a way to test that the abs speed sensor is exactly where my speedo is reading off of? Could I just unplug the wire and drive down the road and the speedo shouldn't move right? There is also two wires coming out of the top drivers side of the transmission, what is that? Thanks
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Old 08-22-2007
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I replaced the RABS sensor and it didn't fix it. What should I do know? Thanks
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Old 08-22-2007
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If your sure the tire size is within spec and you replaced the the sensor on top of the rear end then your left with either the GEM or Speedo head. I would start looking around the junkyards for a 1999 2.5L manual tranny ranger that you can pull the GEM and cluster from.

However, before I'd go to that extent I would make sure its actually reading fast. Either have someone pace you at 60 mph and or find the mile markers on a stretch of hwy and a good watch with second hand and time it through the mile at 60 mph (60 seconds). If its done this since you bought it someone may have pulled the speedo needle at some point and put it back on wrong. If this was done then the only way to get it back close is to pull the cluster and remove the cover and pull the needle off very carefully. Put the cluster back in place without the cover on. Then find a lone section of hwy and have someone pace you at 50 - 60 and then put the needle on. BUT BE VERY CAREFUL...I WOULD HAVE A FRIEND WITH YOU WHO CAN HELP HOLD THE WHEEL WHILE YOU REPLACE THE NEEDLE!
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Old 08-22-2007
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Yes, I have had someone follow me and tell me how fast I was going. How is the needle attached? Does it just slip off and it has little notches so you can reset it? How does the cluster come out? Thanks
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Old 08-22-2007
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Quote:
Originally Posted by cghstrojan08
Yes, I have had someone follow me and tell me how fast I was going. How is the needle attached? Does it just slip off and it has little notches so you can reset it? How does the cluster come out? Thanks

And you're 100% sure your friends speedo is correct? I would still double check either by the mile markers or another friends car just to make sure. Be a shame to go through this just to find out their speedo was off.

The needle is pressed on the shaft. To remove the cluster pull the knee panel under the steering wheel and the metal panel behind it. Next remove the radio bezel. Now remove the 3 screws at the top of the cluster, then the two at the bottom of the cluster. Carefully remove the cluster. You'll have to work it out past the steering column. Once you have it out, remove the half dozen or so torx screws holding the clear cover on.

To remove the needle, either use some heavy string to loop around and under the needle (make sure not to pull against the needle pointer) or if you have an old fork break off all but 2 of the tines and been the ends at 90 and spread as needed so they'll fit underneath the needle and pull off. To replace just press it back on.

Last edited by Rev; 08-22-2007 at 09:21 PM.
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