Hey guys,

need some help. I have a Nordsgog digital speedometer and i can't seem to get it to work with my 3800SC setup. I have called them several times and they claim its supposed to work with the 5V sine wave that the PCM sends through the speedo wire. I have had a speaker attached to the wire and I know that theres a signal coming through the wire, although very faint. I would assume that the gauge would work better if it was seeing the old Fiero type speedo output. How do i wire the 3800 wire so it makes a old Fiero type signal?

Does anyone else use this speedo?

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Earl Sessions
1985 Fiero w/ 1998 Supercharged 3.8 V-6
Best ET:3.0 pulley 12.44 @ 109.19mph
2.75 pulley 12.20@ 110.90 mph


"NO Juice....Just BOOST!"

The 3800 PCM sends out a DIGITAL 4000 pulse per mile GROUND signal which is not the same as the OEM Fiero VSS speed sensor. Sounds like you need to build a speedo buffer like the one pictured below:

You can purchase all of these components at your local Radio Shack.

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power corrupts. absolute power corrupts absolutely.

Custom Chip Burning | Fiero Engine Conversions | Turbocharging | www.gmtuners.com

Darth, thanks for the reply. Would you be interested in assembling one of these and i'll pay you for it? I suck at anything electrical. I mean REALLY suck and want this damn speedo to work proberly and don't want my workmanship to be a possible cause.

Any idea if that circuit (specifically, the cap) would cause a *delay* in the speed signal?? Or maybe the ECM signal is delayed? I'm using a Mitsubishi 3000GT speedometer, which worked 100% with the old Fiero signal, and I connected that circiut to try and get it working (long story, basically I didn't need the circuit, I just needed to install the screws that give the speedo power that I forgot to put back in! LOL) but now for some reason if I take off real quick from a stop, I get to around 40 before the speedo suddenly "snaps" to 40 and keeps climing. Take off slow and it follows the speed, but something is delaying the signal for a second or 2. I'm using a '98 Buick PCM, maybe they delayed the signal for some odd reason for the "old folks" that usually drive the Riviera? I'm happy to finally figure out my own stupidity (not good driving without a speedo!) and get the car driving around. Lildevil - if you haven't got one yet I'd send you the one I built, I don't think I need it.

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Bob Williams
Multi-colored '86 Mutt, a work in progress! (3800SC installation almost done... I drove it!!!! AAAAAAAAAAAGGGGHHH!!! This sucker is FUUUUUUUUUUUN!!! :) )

I used the Cyberdyne gauges a few years back and the signal from the pcm worked fine. How do uou have it hooked up?

damn didn't think this thread was still alive. Crow your jus what i was looking for. I have a NordsKog gauge which is very simular to the Cyberdyne. It has 4 wires ...one power 12 v, one ground, one signal wire, and the otheis not used ( belive its either for dimmer or umthing like that) Its been over a year since i hooked it up. The signal wire goes straught to the speedo output on the PCM. The Power is going to the fuse box. the ground is grounded in the fire wall right now. I tried moving the ground around to about every spot in the car and still did nothing. So i thought the gauge was bad. So i bought another one but it does the same thing. Do you still have the Cyberdynes in your car?

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Earl Sessions
1985 Fiero w/ 1998 Supercharged 3.8 V-6
Best ET:3.0 pulley 12.44 @ 109.19mph
2.75 pulley 12.20@ 110.90 mph


"NO Juice....Just BOOST!"

Yes they are still in the car. Its a 1992 series 1 3800. Make sure that you have the 4000 PPM wire from the PCM. Use the same ground for all of the gauges. When I had a bad ground the speedo would go crazy over 100 MPH.

Ok so your tach and speedo use the same ground? And you wired the speedo directlly to the PCM output. Seems simple and thats what I have done and they jus don't seem to work. I assume the Series 1 uses the same signal as the series 2 right?