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4L80E VSS wiring questions

TTMotorsports

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OK so I'm building my Ford with a chevy 6.0L and 4l80E Tranmission that will be manually controlled and the ECM on the motor is a holley with nothing from transmission or VSS needed. Now I'm gonna be running a electronic speedometer which normally is wired off a pin on the factory ECM but I am not running factory and I have heard you can wire it up to the VSS Directly. Now I believe the VSS has 2 wires and I know they operate on pulse for the computer to rear, just like the speedometer, which will be programmed to read accurately. So what are the 2 wires for the VSS exactly. Both outputs or ??? I know the front VSS on a 4l80E is the ISS, input speed sensor and rear is the output speed sensor, which is the one I need to wire into speedometer. Thanks.
 

TTMotorsports

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OK so I am seeing after more digging the red wire connects to the signal output, aka the speedometer, and the other is a ground wire.
 

u2slow

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My primitive understanding of the dual speed sensors is for the factory ECM/TCM to detect/monitor slippage for whatever reason.
 

Smithy

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OK so I am seeing after more digging the red wire connects to the signal output, aka the speedometer, and the other is a ground wire.
Both speed sensors are magnetic induction, one wire is high the other is low. Not a powered / ground sensor. Both wires are outputs like Total Newb said. There is however a speed sensor signal wire from the pcm that you could tap into.


Any reason why you cant use a gps sender for the speedometer? Its easier to setup and doesn't care if you change axle gear ratios or tire size/
 
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TTMotorsports

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I can use a GPS Sender, which costs a little over $100 BUT I already have the 4l80e transmission and would rather wire up the VSS to the speedo since it is very easy to calibrate it and I don't care about speed when offroading really. It's mainly for street driving to give me a rough idea on speeds.
 

TTMotorsports

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OK gotcha so either of the 2 wires can be hooked up and the speedo programmed off of that, whatever one it is high or low output it doesn't matter once speedo is programmed.
 

Smithy

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Vehicle speed signal that runs from the pcm to the factory speedometer is at pin 50 in the green connector. Should be a dark green wire with a white stripe. You dont have to mess with the sensors on the transmission at all.
 

TTMotorsports

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I am not running stock PCM and I don't have any wiring going to transmission since it's full manual shifting and no computer for that either.
 
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