How to fix an off speedo

[Flashflood]

I realize my speedo has been off by about 5 mph how would one go about fixing that

 

[vroomzoomboom]

i found this a while back if you want to try

 

[Flashflood]

i found this a while back if you want to try

Might be an idea

 

[vroomzoomboom]

how well it works, i cant say. i have never tried it and i would also have to think you would have to make sure the battery is good as well. a lot more safe then trying to jam a need into the spedo while buzzing down the highway

 

[Mbrooks420]

I think the correct way to do it would be with FORScan.

 

[Flashflood]

I think the correct way to do it would be with FORScan.

? What's that sorry?

 

[Mbrooks420]

It’s a computer program that interfaces your OBD2 port. You can modify settings in the computer and access higher level diagnostics and tests a typical scanner cannot.

 

[C420sailor]

Do you need an extended license to do that? I can’t find it in my normal forscan...

 

[Flashflood]

It’s a computer program that interfaces your OBD2 port. You can modify settings in the computer and access higher level diagnostics and tests a typical scanner cannot.

How do I get one of these all the Obd2 scanners I have had don't have this function link to one if possible

 

[CDW6212R]

The calibration of the speedometer is about the change overall of the gauge needle versus speed. I hope the ForScan can do that, but besides that, both tire size or a calibration device can do it. You can change tire sizes to get them closer to the ideal. Stock 91-01 Explorers are calibrated for 30" tall tires, all of them and no matter what the stock tires were.

There are a couple of devices that are made to alter the speedometer signal, they used to cost about $50-$75 used. I have one on my 91 Lincoln that I installed in about 2002 or so, for the 3.73 gears I put in then. Those things are a small box with four wires, and a set of DIP switches inside that alter the ratio of the signal. Those would be the best way if the ForScan cannot do it. They tap into the speedometer wire, plus power and ground.

Installing the needle after it has been removed is an interesting subject. Using a AA battery is cool if it works, but what if it ends up off by 1-2mph, do you take the cluster back out and try it again? I did my 98 on the highway and it took several times to get it back on where it needed to be. I used some local speed displays to check speed, and the cruise control to do the pull and push of the needle back on.

If you know it's off by 3mph at a certain speed, set the CC to that speed first. Then when it's safe, yank the needle and resume that speed, putting it back on, moved 3mph etc.

 

[C420sailor]

Mine reads 2mph fast. Close enough.

 

[CDW6212R]

Mine reads 2mph fast. Close enough.

Mine is near that too. It helps to avoid speeding tickets, I like that.

I'll worry about the speedometer, after I finish altering the tires and gearing etc. I have an extra one of those devices that corrects the speedometer signal too. I'll have to find that again some day.

 

[efBrianM]

i found this a while back if you want to try

Thought I'd post a few comments about this video for anybody that might be thinking about using it.
I used it after I repaired my non-working odometers, but you probably could use it "slip" speedometer needle one way or the other.
Comments:
The needle seems to fit on the shaft pretty snug, don't think you just slip it without taking it of first. In my case, I was essentially trying to put back on in the same spot it was originally.

Before you remove the speedo needle, take a "before" reading. Put a piece of painter's on the cluster face and make a mark where the needle points to when the battery is hooked up. For speedo correction, maybe put another mark at where the needle needs to be moved to.

As mentioned in the video, when its time to put the needle back on, don't push the needle all the way on, just push it on just a little bit. I ended up using a pair of needle nose pliers to hold the motor shaft and then slip the needle a little with your fingers. Be gentle with the pliers. It took me several attempts to get it right.

When your satisfied the needle is pointing in the right direction, push the needle on "most" of the way. Don't push the needle so far on that it touches the faceplate. This may cause some drag on the needle movement, and the speedometer may be jerky, as mine was. To fix, I left the cluster in the vehicle, took the clear bezel off and gently pried the needle out a little. Put some tape on what ever you're using to pry with, so you don't mark up the faceplate.

As stated above, using software to make the correction would probably be the best way, just thought I'd post some comments.