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Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!

Today my neighbor (he has the white Formula) went to the yard to grab some parts for his car and he grabbed me a V8 digital cruise module to replace my AR module. I swapped my mount and the throttle cable onto it, plugged it in, and it worked flawlessly. I'm extremely pleased finally having a Fiero with cruise control. I have decided that I am going to forgo installing a cruise light in the dash, I would if the module was still used in the stock location, but I am really not wanting to deal with running a wire from the digital cruise module all the way to the gauge cluster for a little tiny light.

Here are the links to the how-to's that I used, I combined them together for my installation:

Click on "Articles" and then find "Installing a digital cruise in the Fiero" by Oliver Scholz

I mainly used this one for the inspiration, getting the 4000ppm signal from the speedometer to the module without running another wire, wiring in the clutch release switch, and walking me through where everything was located.

I found out that my install wouldn't work because of the Formula taillight design, so I switched gears and went this route with instructions from Darth Fiero at GM Tuners:

File Index

quote Originally posted by Darth Fiero here: I have had some issues with some of the GM electromotive cruise control units (even those marked "AR") in Fiero swaps not wanting to engage at all. This is when they are NOT connected to the PCM on the cruise inhibit and status circuits. I believe the problem is some of these cruise control modules want to see the cruise inhibit input change state at a certain speed (perhaps?) and that won't happen if you just ground that wire. If you are using a manual transmission in your swap, the PCM may never ground the cruise inhibit wire to enable cruise operation because there is no electronic auto transmission present. Since the discovery of this problem, I have been building my stockpile of 96-99 Cadillac Northstar cruise control modules (they look identical to the ones used on the 3800s; except the Cadillac ones are marked "V8"). Every single 96-99 Northstar cruise control module I've gotten from a Cadillac has worked fine without having the cruise inhibit and status wires hooked up to the PCM. All you'll need to do is permanently ground the cruise inhibit input to the cruise module. Cables can be easily swapped out on these cruise modules so you can use any cable you need to match your throttle body. -ryan

To make this work I used the following:
- V8 digital cruise module as Ryan said
- Grand Prix throttle cable and mount
- I bought my relay from Napa here

Once I had the parts, I used the instructions from both links and it was pretty easy to accomplish.

Finished product, I opted to route my throttle cable down and around the driver side of the engine bay, the throttle cable length was perfect:



Relay location, there was a mounting position right below the cruise module that was perfect:



I do need to figure something out with the throttle cable mount, because I have no idea what is going on with this and I needs to be cleaned up. The previous owner pointed it out to me that he wasn't too happy with it, neither am I, but it's working for now. Maybe next weekend I can find a suitable bracket to fix it. It looks like it was snapped or broken somehow:

[This message has been edited by rbell2915 (edited 08-04-2025).]

[This message has been edited by rbell2915 (edited 09-14-2025).]

quote Originally posted by rbell2915: Went to the yard and grabbed a new throttle cable bracket. I see why zip ties were needed, the throttle cable doesn't fit in there perfectly. I was able to put the cruise cable in though and trimmed the throttle cable moment some and made it work with minimal zip ties.

Ain't nothing wrong with zip ties on the throttle cables! Been using them for years:


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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

[This message has been edited by Frenchrafe (edited 09-15-2025).]

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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM