Georgia Fiero Club Forum
All Things Fiero => Tech Tips, Tech Questions => Topic started by: tech on November 10, 2017, 03:01:09 pm
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Hi,
I'm new, but have followed the forum over the years. I received a nice welcome email from Charlie a moment ago.
I acquired 2 Fiero GTs, as noted below, and would like to hire someone to help me finalize the project, or at least get past the current wiring phase.
1988 GT - manual, acquired as roller with no engine
1987 GT - automatic, wrecked donor/parts car
Location: Acworth, GA (can have car towed)
Current status: Engine (from 87GT) and transmission (4spd from 85) installed in the final car (88GT).
I do not have the harness that would have come with the 88 and do not know how to hook this up. I do not know if this is an issue of acquiring a different harness or modifying the existing one.
I have the ECM from both cars, additional parts from the 87GT and now a 5spd from an 87 that I just acquired.
If anyone is available to do this work or knows someone I could reach out to, I would greatly appreciate it.
Thank you
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Welcome! Good to see you posting.
The harness for the 87GT and the 88GT should be the same, IIRC. The ECU programming is a bit different for 4-speed vs 5-speed.
How many speeds did the 88GT have?
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The engine harness for manuals and automatics are different. Among other things, the manual harness doesn't have provisions for the Torque Converter Control switch. I believe 88 injector harnesses are different, and I know the alternator harness is different.
The automatic ECM can work in a manual transmission car, but not visa-versa because the manual ECM has no provisions for the torque converter. I do believe you can use the 87 harness in the 88, though. Raydar can tell you if he picks up on this thread. He should also be at the meeting, tomorrow.
GTXvette is near you in BallGround and might be interested. f85gtron is in Augusta and has done some extensive rescues and mods on a number of Fieros. He's delved into wiring, suspension, engine swaps, ECM programming, 7730 conversions, digital cruise and much more. I've towed several vehicles down to him to be made roadworthy.
GTXvette may be at the meeting tomorrow, but Ron only gets here when he's passing through from a job assignment.
Log in, find a post by either and click on their username on the left. That will give you their profile email address.
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The harnesses are different between automatic and manual.
The chips are different between automatic and manual. If you have the 88 manual ECM, use that one.
You really need a manual harness, but the quick and dirty way to get it running is to jumper the large purple and yellow wires on the transmission selector switch. That will allow the starter to work. You will also need to re-pin the big yellow wire in the "engine side" of C500 (next to the battery) to mate up with the big purple wire in the "car side" of C500.
Since the 4 speed does not have a reverse light switch, you will need to wire one up to the shifter. The 4 speed shifter has a reverse light switch as part of the assembly. You will need to run two wires to the reverse light wiring that was part of the automatic transmission connector.
Or you could swap in the Getrag 5 speed. Instead of running wires to the shifter, you would just connect them to the reverse light switch on the tranny.
The VSS (speed sensor) wires will also be too long.
If you have any other specific questions, I'll be happy to try to answer them. I don't have the time to do the work, however. Sorry.
Since the 88 ECM is looking for a 5th gear, it will always be turning on the shift light in 4th. You can either swap in an 86 4 speed chip (the 85 chip will NOT work in the later ECM) or just remove the shift light bulb. :D
There were a few other minor wiring issues, converting an automatic harness to manual, but nothing that is a show stopper.
Edit - Welcome to our obsession!
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Thanks everyone for your detailed responses. It's already been an adventure getting to this point, but I'm fairly determined to get it going.
I'll acquire a manual harness. I'm still definitely interested in hands on assistance from anyone who's been down this road before, so feel free to post here or message me if you're available.
I'll keep everyone updated. Thanks again for all of your help.
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You will also need a pre-88 flywheel with balance weights on the backside. 88 engines were internally balanced. Prior engines used balance weights on the flywheel. Also order a clutch kit for an 85 V6 to assure you get the correct throwout bearing. 86's also came with 4-speeds but they also came with 2 other manual transmissions. Parts houses often only list the 2 5-speeds for 86's.
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@fierofool Thanks for the info. Fortunately, I had read about the 88GT being internally balanced and ordered a flywheel from an 86GT. With regard to the clutch, I'll have to confirm part numbers, but I think I did order one for an 85GT because the part store's numbers seemed inconsistent for 86 and 87.
I have ordered a harness from an 1988GT, which will hopefully simplify things. I will keep this post updated.
Thanks again to everyone for the assistance.
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Any progress on this?
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...ordered a flywheel from an 86GT.
If you're ordering it aftermarket, look at it carefully to make sure that's what you get. The presence of the weights on the back of the flywheel should be obvious. If you don't see any weights, you've likely got the wrong flywheel.