with Vinnie on the seat removal 
replacing ecm
Thread Starter
Instructor
Joined: Nov 2006
Posts: 166
Likes: 0
From: Madison WI
replacing ecm
I am replacing the ECM in my 1985 corvette. I was wondering how you go about doing this is it just taking the old one out and plugging the new one in or is it more involved then that. my vette always throws a code 54 fuel pump relay and code 55 ecm failure. It also started detonating could that be related to the ecm.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Ecm
Disconnect the battery, negative cable, and leave the hood up.
lay on the right side passenger foot well, and look up. there is a plastic panel held on by some hex head screws. take these out, and there's a 10 mm nut on the firewall, take that out also.
then remove the courtesy light wire clip, and remove the panel. get back in the footwell, and look up again, you will see the ECM held in by 2 10mm bolts in a plastic case. remove the wire connectors by squeezing the clip angles, and then the computer slides out.
you have to change the eprom from one computer to the other. you will have to take off the little flat aluminum panel that covers it.
Reverse process to install. connect battery, and start it up.
drive 50 miles, and see if any codes reappear.
lay on the right side passenger foot well, and look up. there is a plastic panel held on by some hex head screws. take these out, and there's a 10 mm nut on the firewall, take that out also.
then remove the courtesy light wire clip, and remove the panel. get back in the footwell, and look up again, you will see the ECM held in by 2 10mm bolts in a plastic case. remove the wire connectors by squeezing the clip angles, and then the computer slides out.
you have to change the eprom from one computer to the other. you will have to take off the little flat aluminum panel that covers it.
Reverse process to install. connect battery, and start it up.
drive 50 miles, and see if any codes reappear.
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Right on the money.... make sure you seat the eprom and install correctly... i know its added work, but i've found, for us old timers, that if you remove the pass seat it makes the yoga much easier....
Race Director
Joined: Jun 2004
Posts: 13,943
Likes: 705
From: WI
I just did this and it only took a few mins to drop the computer. I sat on the floor a long side the car and just found the bolts by touch. When I reinstalled the computer I only put the passenger side bolt in, so I can change out chips faster. Dropping the hush panel and computer took under 20 mins.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I've dropped mine a few times without removing the seat (mainly because I didn't know how EASY it is to remove), and had to twist myself around like a pretzel to get to it.
Took me two days to unwind; see, I'm one of those "Old Guys" too. LOL
Jake
Took me two days to unwind; see, I'm one of those "Old Guys" too. LOL
Jake
Instructor
Joined: Jul 2011
Posts: 109
Likes: 0
Wouldn't it be easier to remove the dash pad and go in through the top?
Disconnect the battery, negative cable, and leave the hood up.
lay on the right side passenger foot well, and look up. there is a plastic panel held on by some hex head screws. take these out, and there's a 10 mm nut on the firewall, take that out also.
then remove the courtesy light wire clip, and remove the panel. get back in the footwell, and look up again, you will see the ECM held in by 2 10mm bolts in a plastic case. remove the wire connectors by squeezing the clip angles, and then the computer slides out.
you have to change the eprom from one computer to the other. you will have to take off the little flat aluminum panel that covers it.
Reverse process to install. connect battery, and start it up.
drive 50 miles, and see if any codes reappear.
lay on the right side passenger foot well, and look up. there is a plastic panel held on by some hex head screws. take these out, and there's a 10 mm nut on the firewall, take that out also.
then remove the courtesy light wire clip, and remove the panel. get back in the footwell, and look up again, you will see the ECM held in by 2 10mm bolts in a plastic case. remove the wire connectors by squeezing the clip angles, and then the computer slides out.
you have to change the eprom from one computer to the other. you will have to take off the little flat aluminum panel that covers it.
Reverse process to install. connect battery, and start it up.
drive 50 miles, and see if any codes reappear.
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