True Odometer Reading

[onerareviper]

Viperholics,

I have a 1998 GTS with 3.73 gears. I drove the car for about 5,000 miles, without the speedo-recalibration box installed. Therefore, the odometer reads higher than it really is (I'm thinking around 1,000 miles higher). Is there a way to tap into the computer to see the 'TRUE' mileage, so I can adjust the odometer accordingly?

Thanks

 

[Janni]

And why would you think the computer can figure out the "true" mileage? It would have to know what your gears were, what gear you were in and the exact tire size combo you were running in order to calculate all that "perfectly" I would think if you have not recalibrated the speedo, then the computer is gonna get it wrong, too. Right?

 

[onerareviper]

O.K. I will have to look at my papers to see the exact mileage when the 3.73's were installed.

Thanks

 

[Marc Lublin]

Actually, if you figure out how many miles you drove and figure out percentage wise how much it was off, you can by a recalibration box from Sean Roe and adjust it under the same percent for the same # of miles and get your speedo to be true to what the car actually has on it. Then just make it accurate to the correct speed for the rest of you happy motoring.

 

[grayman]

Exactly as someone above has posted, your computer gets the same reading from the same port (speed sensor) as your odometer. It should be based on revolutions of a reed type circuit and is unaware of any mods youve done which alter the correct rev to output ratio (ie wheel/tire size, gear ratio, etc.). Someone please correct me if Im wrong, but the speed circuit sends a signal to both the computer and the odometer/speedometer in parallel (2 signals). Mileage is read in the computer and on your odometer. However, both use the same signal and port (speed sensor). So if sensor is reading an inaccurracy, it will be reflected in both computer and odometer. Nevertheless, you cant get away with rolling odometer back to what you believe is correct mileage.....legally at least.

 

[Rich Carlson]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by grayman:
Exactly as someone above has posted, your computer gets the same reading from the same port (speed sensor) as your odometer. It should be based on revolutions of a reed type circuit and is unaware of any mods youve done which alter the correct rev to output ratio (ie wheel/tire size, gear ratio, etc.). Someone please correct me if Im wrong, but the speed circuit sends a signal to both the computer and the odometer/speedometer in parallel (2 signals). Mileage is read in the computer and on your odometer. However, both use the same signal and port (speed sensor). So if sensor is reading an inaccurracy, it will be reflected in both computer and odometer. Nevertheless, you cant get away with rolling odometer back to what you believe is correct mileage.....legally at least.
<HR></BLOCKQUOTE>

You have most of it correct. The speed sensor is an input to the PCM which then sends a speedometer signal to the EEM, the speedometer and the radio.

 

[grayman]

Rich,

So all signals go straight from the speed sensor to the PCM?? (this is the computer??) and then get redirected to the speedo?

 

[Rich Carlson]

Yep, the speed sensor signal goes to the engine conroller and then off if goes to the speedo and the radio and the EEM (the electronic entry module).