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Discussion Starter · #1 ·
I've been all over these boards, can't find a good answer anywhere.

I've bought an AVIC-D3 nav system and need to tap into the VSS wire. From what I've read, the true VSS is in the CAN-BUS, but there IS a shaft speed sensor that works just as well. The regular MZ3 owners have been able to tap into a 2-wire harness on top of the transmission, behind the engine.

There must be a helluva lot more room behind their engine than ours, because I can't even see back there, much less reach a sensor. I'm hoping there's another way to do it, or that location is different on the Speed3's (the reason I'm posting here and not in the audio category). Has anyone successfully found a speed sensor on a Speed3?
 

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[quote author=Mark C link=topic=72085.msg1269268#msg1269268 date=1173976770]
I've been all over these boards, can't find a good answer anywhere.

I've bought an AVIC-D3 nav system and need to tap into the VSS wire. From what I've read, the true VSS is in the CAN-BUS, but there IS a shaft speed sensor that works just as well. The regular MZ3 owners have been able to tap into a 2-wire harness on top of the transmission, behind the engine.

There must be a helluva lot more room behind their engine than ours, because I can't even see back there, much less reach a sensor. I'm hoping there's another way to do it, or that location is different on the Speed3's (the reason I'm posting here and not in the audio category). Has anyone successfully found a speed sensor on a Speed3?
[/quote]

I'll be darned. Woudn't the GPS satellites calculate your speed and show you that on the aftermarket NAV screen?
 

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Discussion Starter · #3 ·
[quote author=leofaye link=topic=72085.msg1269302#msg1269302 date=1173977884]
I'll be darned. Woudn't the GPS satellites calculate your speed and show you that on the aftermarket NAV screen?
[/quote]

Yes, but the nav system uses the VSS for increased accuracy. From what I've read, the positioning can vary as much as 1/8 mile without it, and ~50 ft with the VSS connected.
 

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[quote author=Mark C link=topic=72085.msg1269510#msg1269510 date=1173983929]
[quote author=leofaye link=topic=72085.msg1269302#msg1269302 date=1173977884]
I'll be darned. Woudn't the GPS satellites calculate your speed and show you that on the aftermarket NAV screen?
[/quote]

Yes, but the nav system uses the VSS for increased accuracy. From what I've read, the positioning can vary as much as 1/8 mile without it, and ~50 ft with the VSS connected.
[/quote]

Damn that's quite a difference, nice find!
 

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Discussion Starter · #5 ·
Any ideas? I called my local dealerships, they want to charge me shop time to locate the wire. I don't need it THAT badly.
 

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my tom tom has never been farther off than 100 feet and that was with only 4 sats connected...when i get 12 im within 10 feet easy. I wouldnt worry about the hassle unless you want some sort of bragging rights with friends or something.
 

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i thought the AVIC units used that reading so you couldn't view while the car was moving, not to corrilate with GPS stuff?

sorry, i'm no help, i didn't even know the reg. 3 guys found a wire to tap into?
 

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Discussion Starter · #9 ·
[quote author=Mattleegee link=topic=72085.msg1274660#msg1274660 date=1174243894]
The wire is on top of the transmission?
[/quote]

Yup, which is buried below the turbo and other assorted Mazdaspeed3 parts that the regular 3 guys don't have to worry about. I can barely see the damn wire, let alone reach it and tap it. It's got to come back to the ECU somewhere, I just don't know where. I could try putting the car on ramps, but it's 35 degrees outside and snowed yesterday, so that'll have to wait. I found 1 brown wire in each of the harnesses, but I'm a little uneasy randomly tapping wires hoping to find the right one.

As for accuracy, it's not bad, I'd say maybe 100 ft now. However it gets confused when making a turn at an intersection with a parallel road nearby. It's put me on the wrong road a few times, but recalculated pretty quick. This isn't essential, but I feel like my install isn't complete until I find the damn wire.
 

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[quote author=Mark C link=topic=72085.msg1269268#msg1269268 date=1173976770]
I've been all over these boards, can't find a good answer anywhere.

I've bought an AVIC-D3 nav system and need to tap into the VSS wire. From what I've read, the true VSS is in the CAN-BUS, but there IS a shaft speed sensor that works just as well. The regular MZ3 owners have been able to tap into a 2-wire harness on top of the transmission, behind the engine.

There must be a helluva lot more room behind their engine than ours, because I can't even see back there, much less reach a sensor. I'm hoping there's another way to do it, or that location is different on the Speed3's (the reason I'm posting here and not in the audio category). Has anyone successfully found a speed sensor on a Speed3?
[/quote]

is that a double din unit??
 

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Discussion Starter · #12 ·
[quote author=IvanHoe link=topic=72085.msg1276520#msg1276520 date=1174325971]
is that a double din unit??
[/quote]

Yes. I still have to mount the rearview camera (and find a speed sense signal). Hopefully this weekend I'll get that knocked out and post some pictures of the entire install.
 

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Discussion Starter · #14 ·
I'm going to try tapping the wheel speed sensor. Found the wire, kind of a pain to get to from under the hood, and it started raining tonight so I didn't feel like taking a wheel off. I'll post back results when I get around to it.
 

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My TomTom has a gyro(or something) that allows it to estimate distance when its not connected to the sats. Garmin's dont have this?
 

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Discussion Starter · #18 ·
Still no luck. The wires to the speedometer are CAN-coded wires I'm told. I tapped the wheel sensor AT the wheel, neither wire worked. I'm getting close to giving up....
 

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Discussion Starter · #20 ·
That set of instructions is helpful, gives me a little more hope. I'll try that location next. I'll have to figure out what wire connects to that location and tap that, instead of inserting a 'pin' into the harness. I'm surprised it locates the reverse signal all the way at the rear of the hatch. That's where I put mine, but there has to be a spot at the dash also.
 
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