Hey all..

Just out of curiosity...

My `98 1500 Lariat SLT 5.2 speedo is reading off -3-6mph.

When my GPS says I'm doing 83, my spedo says I am doing 79. When I am doing 55, my speedo says I am doing 58, etc.

I have stock size tires, stock drivetrain, and about 245K on everything.

Is there an easy way to calibrate this like I did on my motorcycle, where they have something you can plug in to calibrate the difference?

Or is it back to the old gear in the side of the transmission, that I need to just wait and worry about whenever the transmission decides it wants to die?

Thanks in advance!

 

The 98 is all electronic, so, any good tire store *should* be able to recalibrate your speedo.

 

The speedo showing 58 when actual is 55 mph would be normal, speedometers always err on the side of higher speeds. 79 mph when actual is 83 mph is unusual because theoretically the driver could get a ticket although he/she was led to believe the speed was at/under the limit.

From what I gathered it should be possible to change the revs pre mile in the ABS module but I've never done it.

 

Really!? I will have to call Discount Tire and ask. I bought the tires from them about 4 years ago.

Thanks for the heads up.

 

I guess I mentioned this all wrong - LOL

The speedo is showing lower than the speed I am actually doing. For instance...

Speedo: GPS:
10 12
35 37
45 48
75 79
80 84

 

Yeah, discount should have the ability to correct that for you.

 

So I asked Discount Tire, and she said no.

She said something to the ability of...

"We have the ability to calculate the difference someone's speedo might be off when they buy tires, but we don't have the ability to correct the speedo."

 

Gonna have to be the dealer then...... Either that, or invest in the tool that will let YOU do it..... If it's a one time thing, dealer will be cheaper.

 

I have a 98 as well but with 285's, so my speed o is off.
I recently bought an Autel MaxiDAS 808 scan tool. I did see an option for speed o calibration but haven't tried it out yet. I know sometimes options show up on these tools and don't actually work on that vehicle model, but i will be giving it a try soon. I was wondering what determines the speed, didn't realize it was the ABS module, good info to know.