and i had this idea
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Supreme Member
Joined: Mar 2000
Posts: 2,028
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From: St. Louis, MO
Car: 85' Firebird (Project), 92' RS
Engine: 2.8L, LS1
Transmission: 700R4, 4L60E
Axle/Gears: 3.42 Open , 10 Bolt (ukn)
and i had this idea
The goods....
alright, the wiring is for a vehicle speed sensor, but it gets a tad more interesting, lets see which guru has a thought on this. Ok, my cars an 85 firebird, w/ a mechanical driven speedometer, on the rear of the speedometer is a small conection that goes to the speedo cable and has the odometer connected to it, also are three wires, red, green, and black, these wires all disappear into a small yellow box connected to the back of the instrument cluster....
The Problem....
Well, i'm now switching to a 4th gen dash, actually, i'm switched, wiring's essentially finsihed minus a few minor details, speedometer and HVAC, but those are to come, speedo-first.
The Thought.....
So, i read the article on the interior board about wiring up the yellow VSS box to run the factory speedo, unfortunately, the setup uses two different signals....4th gen (and electric 3rd gen) is 4k ppm, while cable thirdgen is 2k ppm. So here we go, the thirdgens used a VSS buffer box which would convert a 2000ppm signal to a 4000ppm signal for the speedometer, so, i bought the yellow buffer box, now i clipped the old yellow box off the back of the VSS wires, hooked power to the green wire, ground to the black wire, and apparently the red wire is signal (it's akward i know) then hooked those wires into the buffer box, and wired the buffer box accordingly as it should be done, so here's the deal. The speedo still sin't working, no biggie i had no true hope that it would actually move, and that i'd have to swap to a later model VSS in the tranny, but it wasn't quite that straight cut, it actually does move, just not right.
Get this, when slowing to a stop the speedo will actually speed up, sometimes it'll move to 20mph, sometimes it'll move to 10, it's not acurate, also when the transmission is in gear, the car not moving, and the brakes applied, the speedometer will raise up between 0-10 mph, if you hit the gas, it goes to 0 again and won't return unless you're trying to stop. So, what's wrong w/ this scene? If it's possible to convert the ole' cable speedo signal into one for computer and dash alike it would greatly aid all those 4th gen dash conversion people out there, and since i am apparently getting some signal (right or wrong) i actually see some hope in this. I'm going to buy the correct wiring setup anyway, however i'm curious as to what others think of this idea. Please, i'd love to grab as much info from all of you as possible.
alright, the wiring is for a vehicle speed sensor, but it gets a tad more interesting, lets see which guru has a thought on this. Ok, my cars an 85 firebird, w/ a mechanical driven speedometer, on the rear of the speedometer is a small conection that goes to the speedo cable and has the odometer connected to it, also are three wires, red, green, and black, these wires all disappear into a small yellow box connected to the back of the instrument cluster....
The Problem....
Well, i'm now switching to a 4th gen dash, actually, i'm switched, wiring's essentially finsihed minus a few minor details, speedometer and HVAC, but those are to come, speedo-first.
The Thought.....
So, i read the article on the interior board about wiring up the yellow VSS box to run the factory speedo, unfortunately, the setup uses two different signals....4th gen (and electric 3rd gen) is 4k ppm, while cable thirdgen is 2k ppm. So here we go, the thirdgens used a VSS buffer box which would convert a 2000ppm signal to a 4000ppm signal for the speedometer, so, i bought the yellow buffer box, now i clipped the old yellow box off the back of the VSS wires, hooked power to the green wire, ground to the black wire, and apparently the red wire is signal (it's akward i know) then hooked those wires into the buffer box, and wired the buffer box accordingly as it should be done, so here's the deal. The speedo still sin't working, no biggie i had no true hope that it would actually move, and that i'd have to swap to a later model VSS in the tranny, but it wasn't quite that straight cut, it actually does move, just not right.
Get this, when slowing to a stop the speedo will actually speed up, sometimes it'll move to 20mph, sometimes it'll move to 10, it's not acurate, also when the transmission is in gear, the car not moving, and the brakes applied, the speedometer will raise up between 0-10 mph, if you hit the gas, it goes to 0 again and won't return unless you're trying to stop. So, what's wrong w/ this scene? If it's possible to convert the ole' cable speedo signal into one for computer and dash alike it would greatly aid all those 4th gen dash conversion people out there, and since i am apparently getting some signal (right or wrong) i actually see some hope in this. I'm going to buy the correct wiring setup anyway, however i'm curious as to what others think of this idea. Please, i'd love to grab as much info from all of you as possible.
Senior Member
Joined: Jul 1999
Posts: 700
Likes: 0
From: Pineville, NC US
Car: An '87 Italian Retard Out Cruisin'
Engine: LS1 install in progress
Transmission: 4L60e
Axle/Gears: 9 bolt
Do a search. I think Someone posted a couple months back about using the mechanical buffer box with a 4kppm speedo. The post had some pics too. Im not sure if they were still using the ecm though. One day when I ever get time, Im am going to be doing the 4thgen dash also. Been sitting in my basement for a year and a half.
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