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4L80E VSS wiring questions

TTMotorsports

Red Skull Member
Joined
Jan 7, 2021
Member Number
3315
Messages
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Lucerne Valley, CA
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.
 
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.
 
My primitive understanding of the dual speed sensors is for the factory ECM/TCM to detect/monitor slippage for whatever reason.
 
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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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.
 
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.
 
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.
 
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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