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145 MPH speedo swap question

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Old 08-24-2006, 05:16 AM
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145 MPH speedo swap question

Simple, but just a thought. Bought a 145 speedo cluster and its on the way, with the miles on top and KM on the bottom, or USA version.
However I live in Canada, and my 115 MPH speedo cluster has miles on bottom and KM on top, or a CDN version.
Now the speedo is on the way, but will it read correctly when installed cause of the difference of the US and CDN version. Will my computer still have the needle thinking KM's are on the top band instead of miles, throwing everything off?

or am I overthinking this ??

Last edited by patricktroyz28; 08-24-2006 at 05:22 AM.
Old 08-24-2006, 05:59 AM
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Plug and play.

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Old 08-24-2006, 01:17 PM
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I sure hope so!

Will keep you good folks at 3eggen updated on the results...and hope james is correct!
Old 08-24-2006, 02:46 PM
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Like he said, plug and play. Your speedometer cable spins at the same speed no matter what your gauge cluster displays. 30mph means that the cable spins at X speed. All of the speedos are geared to display their speed based on a fixed cable-speed relationship.
Old 08-24-2006, 02:50 PM
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The US and Metric speedometers themselves are even identical. Only the silkscreen on the face is different.
Old 08-26-2006, 10:30 PM
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I was thinking that mine is Canadian, so where it is an electric speedometer (no cable) it's gets speed from the alternating current from the magnet/coil combo mounted on the transmission, goes to the ECM, then these pulses from the ECM to the speedo are thinking that the KMs are on the top, but the new 145 speedo has MPH on the top, throwing it way off.
Old 08-27-2006, 11:56 AM
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The ECM has nothing to do with the operation of the speedometer.
Old 08-27-2006, 03:10 PM
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I have to disagree
The electric speedometer does not have a cable.The alternating current from the speed sensor is sent to the ECM. The ECM modifies the current to a series of direct current pulses at a frequency proportional to the speed of the car. These pulses form a car speed signal that is transmitted to the speedometer.
Old 08-27-2006, 03:54 PM
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No, the signal from the VSS goes directly to both the speedometer head and the ECM. The ECM does not control the operation of the speedometer, or any of the other gauges.
Old 08-27-2006, 04:20 PM
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Originally Posted by patricktroyz28
am I overthinking this ??
Yep.

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Old 08-27-2006, 05:38 PM
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OK then LOL

This is what is throing me off...direct word for word from my 1991 Camaro GM service manual:

SPEEDOMETER
The Electric speedometer does not have a speedometer cable. The source of speed infomation is a small permanent magnet alternating current generator called a vehicle speed sensor, mounted on the transmission. The shaft of the vehicle speed sensor fits into a pinion gear at the transmission output shaft in the same manner as the speedometer cable of a mechanical speedometer system.
When the transmission output shaft rotates, the VSS shart also rotates and turns the permanent magnet near a coil within the VSS. This generates an alternating current in the coil with a frequency that is proportinal to the speed of the vehicle.
The altering current from the VSS is sent to the electronic control module. The ECM modifies the current to a series of direct current pules at a frequency proportional to the speed of the vehicle. These pulses form a vehicle speed siginal that is transmitted to the speedometer

So thats what I formed my opinion from. I guess we will have the final answer when installed!! I will post the result, and I hope I am wrong! BTY thanks for the input, I really do need all the help you guys provide.
Old 09-08-2006, 03:32 PM
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Damn the overthinking LOL...it was plug and play...thanks for the opinions and comments
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