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84 tercel 4wd wagon
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Discussion Starter · #1 ·
I have an 84 tercel 4wd Sr5 that I am putting a blacktop in.


One issue I have run into is the speed sensor for the edu. My tercel has a mechanically driven Speedo and unlike the ae86 it does not have a circuit in place that puts out an electronic signal.

Has anyone come across and solved this issue?

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Senior TN Member
Porsche
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What transmission are you using? The VSS is mounted on the transmission. You can take the output signal, feed it through ADC to convert to digital square-wave signal (like Corolla speedos), and send it to the ECU. I have a standalone circuit that does this if you want me to post the schematic.
 

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Porsche
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C50 series trans? Here's the circuit. Simple enough to contain inside a matchbox-sized box.



All parts available at Radio Shack or mail-order from Mouser, DigiKey, etc. It triggers off 1.4v based upon diodes D2 & D3. You can customize trigger-voltage higher or lower depending upon your input VSS signal.
 

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84 tercel 4wd wagon
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Discussion Starter · #6 ·
Not a C50, I am using a Z52f from the Z5x series built by aisin in the 80's it is a FWD/4WD transmission used specifically for the 2nd gen tercel wagons.
Uses a cable driven Speedo.
Will this circuit still work in that situation?

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Wow, I remember that trans from my '81 Tercel. Made the engine sit really high up.

As a bolt-on solution, you won't get a VSS signal out of it since it doesn't have one. You can a trigger & VR sensor to the output-shaft to use that circuit to generate a VSS signal. Might be easier to use another RWD transmission that has VSS built-in.
 

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84 tercel 4wd wagon
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Discussion Starter · #9 ·
Really want to keep the 4wd this will be my mountain/backwoods toy. Might just try to swap in a different cluster.

I recently acquired an 85 Mr2 so that will take care of my rwd fix.

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