I'm going to wire in an aftermarket gauge into the factory position, I would like to know which wires from which connector(s) I'll need.

I'm going to splice into the wiring for the tach somewhere behind the connector(s) in case I want to revert to the stock one later on.

keep in mind this aftermarket tach is going in place of the stock one, and I will not be running two tachs.

I do not want a bulky tach pudging out and disrupting the look of the interior, which is why I want to put it in place of the original.

I just got done filming a video on installing an aftermarket Heads Up Display in a Fiero which also included a tach display. If only the video were finished editing it would have been something to check out. I'm not at home at the moment to check but I believe if you removes the rear trim from the gauge cluster you'll see a connector plugged in directly behind the tach location. You'll want to locate a solid white wire. I can get you the pin location when I get home if no one else chimes in beforehand. That white wire is the tach pulse wire. You can also tap any pink with a black stripe wire as your ignition switchable power wire.

------------------
87 Fiero GT 3.4 Pushrod with 7730 ECM & DIS
88 MERA #8013
85 Fiero SE with 3.1 pushrod
86 Fiero SE 2.8 stock
http://www.youtube.com/LostNotForgotton

I just happen to have a pic of the HUD I was working on a few weeks ago. The white 0 is the speedo. The round light on the windshield is the tach. My tach gauge is off so I was hoping this one would be more accurate but it is off too so that means the issue is in the transmission.

What does the transmission have to do with the Tach reading?

Oops sorry. I must have been multitasking at work. I didn't mean to say transmission. The speedometer is the one read through the transmission. We're you able to locate the wire you needed. If not I can pop off the trim panel and give you the pin location or take a pic of it?