Tapping into speed sensor?

[sureshotqxc]

I have a 2004 sport GT which I use a bit for slaloms and rallys. With a digital display, rallying has been a challenge as its lacking in accuracy. I'm getting a rally odometer (heliusdesign) for greater precision. My preferred installation would be to tap into the speed sensor/speedometer rather than running a sensor off of the wheels. Works by counting the pulses sent to the speedometer.

Question is this: Would anyone know the various wires and locations that the vehicle speed sensor could be tapped into? One I know of is the brown wire coming off the sensor on the top of the tranny.

Any assistance would be appreciated...

 

[BrianG]

I don't have the wiring chart in front of me, but maybe the tach signal used for remote starters might work? That would be the RPM sensor. I had found the chart online somewhere, maybe a Google search should find it. If not, I'll post it when I get home if I remember. I don't know about the speed sensor though...

 

[goldwing2000]

http://www.msprotege.com/forum/showthread.php?t=79531

You have a 2004 Mazda3 with a digital display? I wasn't aware that was an option. (scratch)

 

[sureshotqxc]

http://www.msprotege.com/forum/showthread.php?t=79531

You have a 2004 Mazda3 with a digital display? I wasn't aware that was an option. (scratch)

Sorry meant digital display with respect to the odometer reading. Vs the old analog where the tenths position would slowly roll from one number to the next. At least with that, you could roughly estimate the 100ths position. With the digital display its reads one number then blinks to the next...

And Re RPM reading, that wouldn't work for this because RPM's will depend on the gear you're in.... The unit does have a connection for RPM's but thats for if you want to set shift point lights. As if I need a light to tell me when to shift.... (uhm)

Many moons ago, cars used to have a direct cable linkage to the speedometer controlling both the needle and the odometer. Most cars now use a vehicle speed sensor (VSS) to send an electrical pulse varying from 0-5V or 0-12v depending on make. Car then converts the number/speed of the pulses into your odo/speedo readings. Its also used by the cruise control.
I need to figure out where to tap into that. I believe one source is the sensor on top of the tranny at the back of the engine compartment but not completely sure. There should be several places where i can tap in. just need to figure out where...

 

[goldwing2000]

Many moons ago, cars used to have a direct cable linkage to the speedometer controlling both the needle and the odometer...

...I need to figure out where to tap into that. I believe one source is the sensor on top of the tranny at the back of the engine compartment but not completely sure. There should be several places where i can tap in. just need to figure out where...

Heh... many moons ago. I still have two vehicles with speedo cables. It wasn't that long ago.

If you check that link I posted, it gives a wiring diagram to where the VSS signal can be accessed.