Ecm/ecu
Thread Starter
3rd Gear
Joined: Apr 2015
Posts: 3
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Ecm/ecu
I need help getting to and replacing my ECM in my 86. It is not responding to an Obd1 and i think it is responsible for dumping to much fule into my pistons, most likely i have a vacuum line that is damaged and i need to replace that first but i need to take care of this as well... plus the new ECM is only 85 bucks at O' Riley's. any and all help is appreciated.
Thread Starter
3rd Gear
Joined: Apr 2015
Posts: 3
Likes: 0
i think there is a screw behind it but i cant seem to get there? any suggestions? and if you know is there any way to replace it with an open cubby instead of the pillow?
Team Owner
Joined: Sep 2001
Posts: 62,127
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
You only need to remove the lower black hush panel, you don't take out the breadbox and you don't remove the carpeting.
I think its 3 or 4 screws holding the panel in, feel up inside and you'll feel two bolts that hold the ECM up in there. From memory I want to say they are 10mm. You will need a wratchet and I prefer 1 long extension.
GENTLY tug on the harness once you've removed the bolts, and wiggle the ECM out.
and PAY ATTENTION to how the PROM is mounted in the computer box.
I think its 3 or 4 screws holding the panel in, feel up inside and you'll feel two bolts that hold the ECM up in there. From memory I want to say they are 10mm. You will need a wratchet and I prefer 1 long extension.
GENTLY tug on the harness once you've removed the bolts, and wiggle the ECM out.
and PAY ATTENTION to how the PROM is mounted in the computer box.
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
Done this many times on my 89, so if yours is same as mine, Don't remove dash panel. Underneath the pass side, remove kick panel that has interior lite in it. There are several screws with the hardest up next to the fire wall. Once the kick panel is removed, look up under dash and you will see a metal box. That is your ecu box.
There will be two plugs, I think blue in color, one wider then the other, snapped into it. Remove them by pushing on the release tabs on each plug
There are two self tighting screws, one on each end of box .
Remove them and pull down on box. Be careful not to snag any other wires or vacuum lines as you work box down and out.
When you re-install ecu box make sure you install it so that when you plug back in the two connectors, the push in release tabs on the plugs face toward the seats in the car. The plugs are different in width and only go in one way.
If I can do it, anyone can.
Hardest part is getting it in and out around existing wires in the area
There will be two plugs, I think blue in color, one wider then the other, snapped into it. Remove them by pushing on the release tabs on each plug
There are two self tighting screws, one on each end of box .
Remove them and pull down on box. Be careful not to snag any other wires or vacuum lines as you work box down and out.
When you re-install ecu box make sure you install it so that when you plug back in the two connectors, the push in release tabs on the plugs face toward the seats in the car. The plugs are different in width and only go in one way.
If I can do it, anyone can.
Hardest part is getting it in and out around existing wires in the area
Last edited by mlm0; May 13, 2015 at 08:01 AM. Reason: Wording
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
There is a good chance its not the ecm.
On a Cadillac for instance and some other vehicles the computer wont communicate if the check engine light is blown or missing. People remove them to not show the check engine light all the time.
Also if the plug doesn't have power it wont read on some scanners.
Finally obd1 scanners are fickle as it gets with what they will work with. I get people all the time coming to me to scan their obd1 stuff since not many around here can read them reliably.
Be very careful when changing the prom out if you do decide to swap it out.
On a Cadillac for instance and some other vehicles the computer wont communicate if the check engine light is blown or missing. People remove them to not show the check engine light all the time.
Also if the plug doesn't have power it wont read on some scanners.
Finally obd1 scanners are fickle as it gets with what they will work with. I get people all the time coming to me to scan their obd1 stuff since not many around here can read them reliably.
Be very careful when changing the prom out if you do decide to swap it out.
