Replace your Fiero computer? (Page 1/1)
Kitskaboodle SEP 16, 11:34 PM
I’m about to swap out my computer on my 85 GT. I have never done this before so I have a few questions.
Before we start, I got a used computer from an 85 SE V6 car.
Anyways, I know there is a rectangular cover on the computer that has two replaceable chips (IC’s) in them. When I take my old computer off, I will remove the cover and see if the chips have matching information as the one I’m swapping in. Will this be likely? (that they will be matching) or should I automatically swap out the chips just in case? As an fyi my car is an auto and I don’t know if the donor car was a stick or auto.
Next question is… will the “swapped” computer cause my Fiero to go “crazy” for a while until it learns it’s new home and sensors?
Any tips on removing the chips if I have to do it?
Thanks, Kit
P.S. Here’s two pics of the computer from the donor car.
theogre SEP 17, 02:19 AM
Applies to most GM OBD1 ECM...

1. Disconnect the Battery Neg
2. Remove the ECM
3. Swap PROM and MEMCAL if it has that. (Second small "chip" shown above. Some not or have it "bundle" w/ the PROM.)
4. Install new ECM
5. Connect Battery

⚠️ Warning: Use Anti-static Strap etc to handle the ECM PROM and MEMCAL. More so If weather is dry.

As always will need to Reset the IAC but will work. Drive > 35mph will make the Reset for most ECM. Some versions like 87-88 Fiero 4cyl will also Reset while Parked when push gas penal to get > 2200 to 2500RPM for a few seconds.

PROM and maybe MEMCAL in replacement ECM is likely same If car has same transmission.
But...
If one is auto, other stick... then PROM are program to work with them like 1 ECM pin runs TCC locking or the Shift light.
If one is made for California and other isn't then one set of PROM, MEMCAL, or both is program for CA CARB rules.

If ECM came out of different model...
Even if have same Engine and Trans the PROM may not work in Fiero. Example: Some ECM versions like 87-88 Fiero 4cyl then PROM are also program to work with different VSS types for FWD cars.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 09-17-2022).]

Kitskaboodle SEP 17, 07:34 PM
Thanks Theogre!
I was able to swap out the chips from my old computer in my 85 GT to the donor computer. I had an esd wrist / ground strap going to AC ground so no problem with touching & handling the chips.
Anyways, my car started right up and ran just fine. I took it out for a 15 minute test drive just in case the computer has to do any re-learning or re-adjusting.
Thanks, Kit

P.S. Just out of curiosity, when I took the rear console off to access the ECM, I saw this little electronic black box. (to the left middle of the ECM) What is this?
Patrick SEP 17, 08:42 PM

quote
Originally posted by Kitskaboodle:

What is this?



OMG... that's a C822I376A tracking device!
theogre SEP 17, 10:37 PM

quote
Originally posted by Kitskaboodle:
What is this?

Isn't a factory option...
Hard to tell w/ wires wrapped around OE wires. Saved a copy to edit to see colors below and still can't really see.
Very carefully follow the wires to what wires the tap or worse tap and cut OE wires.

follow the blue and crap white ground in black jacket to Find the other end and whatever attach to it if anything.
If you keep whatever... Move the ground. Like below ECM where already is an OE ground listed as G202.

MAYBE>>>
Alarm disable the engine.
Part of "Kill switch" some used car dealers use.
Alarm monitoring whatever or auto turn on/off.
Patrick may not be far off is some type of tracking/tracing.
could even be part of High Brake "Kit" sim to covered in https://www.fiero.nl/forum/...HTML/146359.html#p12
Patrick SEP 18, 12:05 AM

quote
Originally posted by theogre:

Patrick may not be far off is some type of tracking/tracing.



Ah ha, I knew it!