Copy this and print it for your mechanichttp://www.gmtuners.com/fil...203_C500_pinouts.pdf
All 2.5 & 2.8 body harnesses are the same for 85 - 88 years as far as the engine pinning with a few exceptions. Ignore the 84 exceptions.
The 85 - 88 body harness puts the starter wire on a different pin depending if the harness is AT or MT. (that is the problem that you are finding) The engine harness has to match up with the body harness in this regard.
On some 85 harnesses C500 A1 is used for the trunk release. 86+ has this wiring not running over the engine harness. This shouldn't even apply to you.
The harness will work fine once he changes the pin on the engine harness. The pin on the engine harness can be depinned and moved to the correct location. You have to FIRST remove the WHITE pin secondary retention fork from the side of the C500 connector. This fork is sometimes buried in black gunk. It is on the side of the ENGINE harness connector. Remove the hood and then scrape with a small screwdriver and you will see it. Then use a depinning device to untang the starter wire. It will pull out the back gently after being detanged. After you pull it out. bend the tang back up and put it in the right spot. Put the white fork back in and put the hood back on.
You won't have a clutch safety switch unless you add it. You also won't have a 'shift' light since they weren't used on 88 Fieros.
Someone else doing the same thing - pics and everything too - http://www.fiero.nl/cgi-bin...8863&style=printable
[This message has been edited by phonedawgz (edited 07-13-2013).]