This is the solution I used in my '70 Bonneville:
https://www.dakotadigital.com/index....rod/prd886.htm
It accepts the VSS output from my 12200411 PCM and drives the stock mechanical speedo perfectly.
The box is easy to mount and hide behind the dash.
-Scott
Allow me to revive this thread about speedometer options for the 94 LT1 in the 79 Malibu.
Does the 1994 Z28 PCM speed signal output deliver a square wave signal? If so i think this 2 1/16” gauge might be a solution for a low budget. Id mount it in a pillar pod. Do you think it will work? The install instructions are also available at the linked page.
https://www.glowshiftdirect.com/10-c...dometer-gauge/
John - '79 Malibu Wagon - LT1 - 4L60E
the input to the PCM is analog (40 tooth reluctor wheel), the output is either 2000 ppm or 4000 ppm squarewave. I would just bite the bullet and buy the speedhut or Dakota digital mechanical converter and use the original speedometer.
why don't you just use a cellphone or gps for speed?
I dont like the lag time of gps sourced speedometer.
You are right however. I should bite the bullet and get the Dakota speedo driver. The factory speedometer is in good order and it would be nice to use it. Ill probably eventually pry $350 out of my wallet and do it that way.
John - '79 Malibu Wagon - LT1 - 4L60E
I wish there was a cheaper alternative. there is thE diy route but i just don't have the time. hooking up an existing speedometer motor with gm stuff is actually fairly easy. However the deal breaker for me is a non-functional odometer. you need a unit that screws to the existing speedometer head. I have seen companies that offer to convert existing gauges, but they stick a digital odometer in place of the old mechanical one. it works but not for me.
I would check out the Speedbox from Speedhut, i have heard it is quieter than the Dakota unit and i think can be mounted under the hood. They are actually on sale right now, I might pull the trigger myself as I will need one for my project soon.
speedhut.com/categories/speedbox.html
PCM output is 4000ppm assuming the PCM is calibrated. It's a transistor driver to ground, so it needs a pull-up resistor to work.
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