Speedometer Needle Calibration

[tacticalcherry]

I just had the speedometer needle off on my 99 Tahoe to replace the speedometer motor which had gone bad, and I don't know how I should place it back on and have it read accurate. Placing it at 0MPH when the truck is at a stop doesn't seem to work and the reading is about 5mph too high. I tried cruising at about 35MPH and putting it on there which somewhat worked, but it was difficult to control the car and accurately push it on so I want to avoid doing that (especially since I live in a somewhat busy area). I'd like to know if there is any other way to accurately get the speedometer needle back where it should be. I was thinking if there is any way to have the speedometer read a certain speed without actually moving the car so I can set the needle to that speed, but I don't know if there is any tools that can make that possible.

 

[DieselTech]

I just had the speedometer needle off on my 99 Tahoe to replace the speedometer motor which had gone bad, and I don't know how I should place it back on and have it read accurate. Placing it at 0MPH when the truck is at a stop doesn't seem to work and the reading is about 5mph too high. I tried cruising at about 35MPH and putting it on there which somewhat worked, but it was difficult to control the car and accurately push it on so I want to avoid doing that (especially since I live in a somewhat busy area). I'd like to know if there is any other way to accurately get the speedometer needle back where it should be. I was thinking if there is any way to have the speedometer read a certain speed without actually moving the car so I can set the needle to that speed, but I don't know if there is any tools that can make that possible.

You might be able to do a sweep test on the speedo with a scanner. I'm not sure if this is possible or not.

 

[Scooterwrench]

You might be able to do a sweep test on the speedo with a scanner. I'm not sure if this is possible or not.

Kinda what I was thinking. Set it up on stands,put it in gear and push the needle on the right spot with the reading off the scanner. Trick may be to lightly set the needle on the stem then you can move it and push it on where you want it.

 

[tacticalcherry]

I wouldn't do stands, since the only spot I have to get the car up on them is my driveway which is at a steep incline, I already almost had an incident there. If anything, cruising at a set speed and getting the needle on there still beats using stands, for me at least. I'm mainly looking to see if anyone knows about a way to do so using a scan tool to get the speedometer to read a certain number without actually driving the car

 

[Scooterwrench]

I wouldn't do stands, since the only spot I have to get the car up on them is my driveway which is at a steep incline, I already almost had an incident there. If anything, cruising at a set speed and getting the needle on there still beats using stands, for me at least. I'm mainly looking to see if anyone knows about a way to do so using a scan tool to get the speedometer to read a certain number without actually driving the car

Not without having the driveshaft turning. Try the trick I said using the cruise control to keep the speed constant.

 

[DerekTheGreat]

For safety, take the rear wheels off too. Just make sure to put the lug nuts back on. I've contemplated doing this as my speedo is about 4mph off @ 70mph. Been contemplating that for about seven years now, so why not make it ten?

 

[Scooterwrench]

For safety, take the rear wheels off too. Just make sure to put the lug nuts back on. I've contemplated doing this as my speedo is about 4mph off @ 70mph. Been contemplating that for about seven years now, so why not make it ten?

You won't be able to use the CC with it on stands. I tried that when setting my aftermarket speedo and it started going into an oscillation then pulled the throttle WFO and then tried to correct for it and fell out of cruise.

 

[DerekTheGreat]

You won't be able to use the CC with it on stands. I tried that when setting my aftermarket speedo and it started going into an oscillation then pulled the throttle WFO and then tried to correct for it and fell out of cruise.

Jeebus.. Good to know, I'd have probably **** myself if not in the driver's seat when it did that.

 

[AuroraGirl]

when you raise a rear tire, and spin it, your speedometer will only indicate half the actual speed. this is only true if one tire cant rotate
If you run a vehicle too long or too fast doing this you can easily overheat your engine (not enough air flow)

 

[Scooterwrench]

when you raise a rear tire, and spin it, your speedometer will only indicate half the actual speed. this is only true if one tire cant rotate

Huh? The VSS reads driveshaft rotation not tire rotation. Makes no difference whether you raise one tire or both. For safety reasons you'd be best off raising both especially if you have any kind of locker in the rear.

If you run a vehicle too long or too fast doing this you can easily overheat your engine (not enough air flow)

Best fix the cooling system. If it can't handle running with no load you've got problems.