# Tying into speedometer signal



## ChevyGuy (Dec 13, 2014)

Unless you can either pick the signal off the car's speed sensor directly, or tap into the car's computer bus, I don't think you can. This isn't a normal car. Everything is computerized. And I'm pretty sure that includes the signal from the module connected to the speed sensor back to the interment cluster.


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## EricSmit (Dec 21, 2016)

But why?


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## EricSmit (Dec 21, 2016)

My ultragauge can read miles, so I know it's in the pins somewhere.


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## pelfrank (Mar 23, 2015)

Why not get a OBDII bluetooth/wifi reader and Torque app (some other app) to get your speed reading ?


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## Snipesy (Dec 7, 2015)

This will be a single frame message sent over the high speed CAN. $0C9 $07 $XX $15 $D0 $XX $XX $XX $XX don't worry what the xxs are those are other things. That $15 $D0 is the engine rpm, in decimal its 5584 divided by 4 is 1396 rpm. The message is sent about 60 times a second without command. This is what drives the instrument cluster and anything else that is listening in.


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## ChevyGuy (Dec 13, 2014)

Snipesy said:


> This will be a single frame message sent over the high speed CAN. $0C9 $07 $XX $15 $D0 $XX $XX $XX $XX don't worry what the xxs are those are other things. That $15 $D0 is the engine rpm, in decimal its 5584 divided by 4 is 1396 rpm. The message is sent about 60 times a second without command. This is what drives the instrument cluster and anything else that is listening in.


Ar the risk of forking, where do I find more info about what's sent over the CAN?


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## Snipesy (Dec 7, 2015)

ChevyGuy said:


> Ar the risk of forking, where do I find more info about what's sent over the CAN?


I don't even think GM knows where to find that info :icon_scratch:.


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## EricSmit (Dec 21, 2016)

Snipesy said:


> I don't even think GM knows where to find that info :icon_scratch:.


They sure pretend to.  

Asking Ultragauge or another OBDII dongle company would probably benefit the OP more than asking GM, that's for sure.


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## Snipesy (Dec 7, 2015)

Not too long ago (like 2009), these things would have dedicated wires. They were alot more primitive and I am guessing the op has something that needs to plug into that.


It doesn't work that way anymore, and never will. You'd have to attach your own sensor which isn't worth the effort, and you're never going to be more accurate than the ECM.

You can also request engine rpm from the ecm through the traditional sae method. There are plenty of examples of doing that, and the best reference for that is probably the wikipedia article.


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## TotC (Dec 6, 2016)

pelfrank said:


> Why not get a OBDII bluetooth/wifi reader and Torque app (some other app) to get your speed reading ?


I don't want the speed reading. This is for a rally odometer, to read increments of miles, in fact, the one I have will read 1/100ths of a mile. You can calibrate quite accurately with a known measured distance.


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## TotC (Dec 6, 2016)

Well, I can attach a hall effect sensor and drive the odometer from it. That is how rally cars do it. I just would have preferred to tie into the car's existing system, but it sounds like it can't be done.


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## EricSmit (Dec 21, 2016)

EricSmit said:


> My ultragauge can read miles, so I know it's in the pins somewhere.





Snipesy said:


> This will be a single frame message sent over the high speed CAN. $0C9 $07 $XX $15 $D0 $XX $XX $XX $XX don't worry what the xxs are those are other things. That $15 $D0 is the engine rpm, in decimal its 5584 divided by 4 is 1396 rpm. The message is sent about 60 times a second without command. This is what drives the instrument cluster and anything else that is listening in.





EricSmit said:


> They sure pretend to.
> 
> Asking Ultragauge or another OBDII dongle company would probably benefit the OP more than asking GM, that's for sure.





Snipesy said:


> Not too long ago (like 2009), these things would have dedicated wires. They were alot more primitive and I am guessing the op has something that needs to plug into that.
> 
> 
> It doesn't work that way anymore, and never will. You'd have to attach your own sensor which isn't worth the effort, and you're never going to be more accurate than the ECM.
> ...


We gave you the information.


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## homerz777 (Oct 14, 2017)

TotC said:


> I would really like to be able to intercept the signal to the speedometer, and use it to drive a separate odometer. Does anyone know where the car receives the signal from? Where does it go to? ( I assume the body computer ) Any details or pointing towards a resource I can peruse would be most appreciated. Thanks


It depends what engine type and model the cruze is. For example the F16D4 takes reading from wheel speed sensor and interprets it electronically but if it's an F16D3 it has a speed sensor on gearbox same as a Corsa C. There's 3x wires. 12v +; earth and speed pulse.

Sent from my SM-G930F using Tapatalk


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## Blasirl (Mar 31, 2015)

homerz777 said:


> It depends what engine type and model the cruze is. For example the F16D4 takes reading from wheel speed sensor and interprets it electronically but if it's an F16D3 it has a speed sensor on gearbox same as a Corsa C. There's 3x wires. 12v +; earth and speed pulse.
> 
> Sent from my SM-G930F using Tapatalk



Do you have a list relating what "speed sensor?" goes with what engine/trim combo?


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