1985 EA82T ECM / ECU check engine light

[gbacon67]

Hello All,

I have a 1985 EA82T installed in a homebuilt aircraft.  The engine runs very well, however, the "check engine" light is on.  I tried to reset the ECU by disconnecting the battery and connecting the positive lead to the negative lead to discharge any remaining juice in the ECU.  The light is still on.  This ECU is pre OBDII, so there is no port for connecting a scanner.  Please help if you know how to clear codes on these vintage ECUs.

[DaveT]

Read the code by counting the blinks on the red led visible in a hole on the ecu.  If something is triggering a code, it will just come back.  If nothing is triggering a code, the cel should go off on its own.

[gbacon67]

OK, thanks Dave.  I just now looked with ignition on, but engine not running.  I see on blink followed by two quick blinks, then it repeats after a short pause.  Does this indicate trouble code "12"?

[DaveT]

Correct, long blink is 10s short blinks are 1s.  I don't remember what 12 is , don't have the manual here.  There might be a list one the forum, or someone will have a thread on that code.

[azdave]

Does this thread give any clues?

 

[Steptoe's photos]

Whoa - in car , we have to connect a normally disconnected pair of diagnostic plugs that are green - in order to read trouble codes , from memory.

There are two levels of diagnostics with the 85 EA82T - the other having some reference to being 'dealer' related. I can look more up if needed. That code 1-2 turns up as a bum steer more often than not according to reports over the years. Maybe Earth points need cleaning up. EA82T in an aircraft !! I need photos   General Disorder might be having conniptions reading this !! From memory, when all is good, and engine running, that red LED then blinks to show O2 sensor working OK

Edited September 8, 2022 by Steptoe's photos

[DaveT]

Active codes are displayed with no connectors.  Read memory stored  codes uses one set, clear memory uses another.  Along with some other steps.  With my EA82SPFI engines, I never needed to do either, since 1988.  

[scoobydube]

The wire that goes into the nut attachment on the back side of the alternator, can get hot, brittle and lose conductivity before it breaks altogether.  That used to give me that code.  Otherwise, do a search of my posts on here where I list about a dozen different electrical problems that cause engine failure and/or failure to start.

[scoobydube]

An additional common problem is that the black computer chip assembly inside of the distributor, may be about to go out entirely.  Always have a spare distributor that works.  The plugs getting worn down, will cause occasional missing and help blow out the alternator prematurely.  The ground wire to body, can get hot, brittle and lose conductivity resulting in lack of power to the engine and accessories.  A bad Oxygen sensor in the exhaust can set that light off.

[scoobydube]

Single defective items that can by themselves keep the engine from starting and has put thousands of Subarus in junk yards:

1. the black fusible link is the main engine but any of them can start to break or get hard and brittle, causing intermittent and then total failure.

2.  the thing a ma jig that bolts to the body, directly behind the fusible link box, that had one wire to the coil and the long black wire running to left side engine attachment next to the battery, where the ground wire attaches.  The thing a ma jig also keeps static off of your radio and right before it blows, you get a lot of radio static.

3. the main engine ground wire get brittle and loses most of it's ability to conduct electricity and ground out the engine, at it's attachment to the frame.  This single defect will cause the engine to run poorly when you operate any other accessory on the vehicle.  For instance, you can almost kill the engine by operating your electric windows, if you have them.  THIS IS THE MOST PROBABLE CAUSE OF YOUR PROGRESSIVE FAILURE.  These wires may not last more that 250,000 miles.

4. a loose wire inside of the distributor cap

5. the short wire between the Positive battery terminal and the fusible link box, gets hard at the terminal end, brittle and loses most if not all of it's ability to conduct electricity, causing poor performance before a total engine failure.  You splice in a new lead to the battery terminal, by splaying both ends of the two wire ends that you are joining, in order to get the maximum about of contact surface.

6. the distributor electronics just suddenly went out.

7. the hot wire that runs into the back of the alternator, gets brittle, hard and breaks, causing the engine to perform poorly before it suddenly fails.

8. bad plugs will cause your alternator to fail prematurely.  Some plugs require replacement every 15,000 miles.

9. coil failure or corrosion inside of the lead wire from the coil to the distributor.

10.  Bonus:  a failure of the replaceable round switch below the dash board, to the left of the steering column, will cause the interior fan to suddenly fail, especially if you had just been running it at it's maximum speed.  There are about 5 of these identical switches below that dash in the same location so you are going to have to get a known good switch and plug it into each switch socket, one at a time, before you find the burned out one.  There may be black discoloration on the burned out one.

[photorich65]

Great information scoobydube !  Any chance you have a place to start in my search for EA82T distributors ?  Both my '86's are running on a wing and a prayer with high mile units.

Rich

[Steptoe's photos]

I put up a want ad title some years back. One offer came up in the US. I did not take it up.

Maybe you could try same?

[scoobydube]

On 12/8/2022 at 4:46 PM, photorich65 said:

Great information scoobydube !  Any chance you have a place to start in my search for EA82T distributors ?  Both my '86's are running on a wing and a prayer with high mile units.

Rich

John's subaru in Laurelwood, Oregon has distributors.