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1985 Fiero GT
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MAR 04, 07:56 AM
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| quote | Originally posted by 82-T/A [At Work]:
I have a diagram somewhere, but the ECMs are the same across the board for certain years... it's the EPROM / PROM that's different, and the wiring harness.
Let me see if I can find it:
EDIT: Yeah... so the ECMs are the same for all years except 1985. The 1985 ECM is actually a bit nicer (I'm told) than the other years, and has provisions for a knock sensor to be installed... just lacks the leads on the wiring harness, and a bit to be flipped in the PROM. But what you'll want to do is get a new PROM.
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That's for the v6s, this is for a 4cyl, probably the same situation though
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82-T/A [At Work]
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MAR 04, 08:32 AM
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| quote | Originally posted by 1985 Fiero GT:
That's for the v6s, this is for a 4cyl, probably the same situation though |
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Shoot... sorry. Yes, it's the same deal with the 4 cyls. I know I have a diagram for it somewhere, but I can't find it now.
But yes... buy the PROM that you need, the ECMs are the same.
I wish I had known, I had a complete 5-Speed wiring harness, but it was from an 88 (slightly different). I ended up selling it on eBay for basically nothing (just didn't want to throw it out).
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olejoedad
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MAR 04, 09:24 AM
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| quote | Originally posted by 82-T/A [At Work]:
Shoot... sorry. Yes, it's the same deal with the 4 cyls. I know I have a diagram for it somewhere, but I can't find it now.
But yes... buy the PROM that you need, the ECMs are the same.
I wish I had known, I had a complete 5-Speed wiring harness, but it was from an 88 (slightly different). I ended up selling it on eBay for basically nothing (just didn't want to throw it out). |
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If using a manual transmission engine harness when performing an auto to manual swap, the engine side C500 plug would need to have the SOLENOID wire moved from E2 to A4 to match up with the automatic transmission chassis side C500.
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LS4FieroGuy
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MAR 04, 09:56 PM
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1985 Fiero GT
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MAR 05, 01:04 AM
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| quote | Originally posted by LS4FieroGuy:
What's the PROM? |
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The actual programmed memory of the ECM, it is removable, just a single chip, I think behind a removable panel on the ECM.
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LS4FieroGuy
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MAR 05, 01:07 AM
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| quote | Originally posted by 1985 Fiero GT:
The actual programmed memory of the ECM, it is removable, just a single chip, I think behind a removable panel on the ECM. |
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How do I get the correct PROM?
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82-T/A [At Work]
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MAR 05, 07:59 AM
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| quote | Originally posted by LS4FieroGuy:
How do I get the correct PROM? |
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The PROMs rarely go bad, so even if you buy a used ECM, you can still use the PROM from it. Here's a list of Fiero PROMs / ECMs on eBay:
https://www.ebay.com/sch/i....=p4432023.m570.l1313
This one here says it's for a 1987-1988 Fiero 2.5 / Manual Transmission: https://www.ebay.com/itm/146260148870 for $49 bucks. That one should work, and you should be able to swap it out with the one you already have.
If you look at the ECM you have now, there's a little panel on the face of it. It's held on by two 7mm screws. You remove those two screws and the panel comes off the front, and you'll see the chip. Be very careful, but you pry the old chip out, and install the new chip. MAKE SURE you look at where the original chip was installed. You CAN accidentally install it backwards, and it will ruin the chip. There's a notch on the chip holder, and also a notch on the chip socket (on the motherboard). The notches need to line up.
Here's an image I found (not mine) that shows a Fiero ECM with the panel off... you can see where the chip is (the larger one at the bottom). Take note of the notch, and make sure you install the new chip in the same direction with the notch facing the center.
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