25 minutes ago, Zed Head said:

Intermittent electrical problems are really hard to diagnose. I was testing a spare 1978 ECU and it did what you describe. Died, started right up, died again a half mile after, wouldn't start again.

Had an ignition module that worked fine until it over about 3,000 RPM. Then the tachometer got weird, reading high and needle jumping around, and the engine ran poorly. Turned off the engine, restarted, and it was back to normal.

All you can do is collect the clues and make your best guess.

Definitely true. If it helps, the tach needle didn't jump around before it died, or if it did, my eyes weren't drawn to it. This happened idling at a stop light maybe 10 minutes after driving 20 minutes at around 3500 rpm on the highway. If it is the ECU, are all ECUs compatible with a 1978, or do I need one identical to the label in the picture?

I believe I just laid hands on one of those in the shop the other day...

I might have one as well.

Is there a way for me to test my ecu? I've opened it before and I didn't see anything suspicious/cold solder joints.

Edited May 3May 3 by chaseincats

There are people here that said they purchased a referb unit but never mentioned where they bought it. Best bet is to find a known good ECU from someone here.

Edited May 3May 3 by Yarb

On 5/2/2026 at 1:25 PM, Zed Head said:

Intermittent electrical problems are really hard to diagnose. I was testing a spare 1978 ECU and it did what you describe. Died, started right up, died again a half mile after, wouldn't start again.

Had an ignition module that worked fine until it over about 3,000 RPM. Then the tachometer got weird, reading high and needle jumping around, and the engine ran poorly. Turned off the engine, restarted, and it was back to normal.

All you can do is collect the clues and make your best guess.

@Zed Head Do you think these two issues (the stumble at speed with the tach needle possibly not moving) and the shut off at a traffic light with the needle not moving could be related?

@Yarb @Patcon Any idea if the ones you have work and what you would sell them for if my ECU ends up being the issue? It doesn't sound like there's a way for me to test it.

Edited May 4May 4 by chaseincats

I do think it’s electrical heat related components within the ECU or ignition module. I’ll double check to see what I have.

13 minutes ago, Yarb said:

I do think it’s electrical heat related components within the ECU or ignition module. I’ll double check to see what I have.

Sounds good. If it helps:

my ignition module's part number is: E12-27 8328

my ECU module's part number is: A11-601 000 8317

I have some ECU's an A11-600-000 and A11-601-000 Charts seem to be all over the place as to what cars they were in. MT and AT

I have no way to test them but they are visually undamaged.

3 minutes ago, Terrapin Z said:

I have some ECU's an A11-600-000 and A11-601-000 Charts seem to be all over the place as to what cars they were in. MT and AT

I have no way to test them but they are visually undamaged.

Gotcha - unfortunately, there is apparently no way to test them as mine looks brand new too. Pretty frustrating.

There’s a chart floating around here somewhere. Where’s Cliff aka Librarian “Siteunseen”?

Just now, Yarb said:

There’s a chart floating around here somewhere. Where’s Cliff aka Librarian “Siteunseen”?

Are you talking about the one in the first post on this thread?

It looks like the automatics get the 601 ECUs and the manuals get the 600. My car was originally auto and the PO changed it to manual but the 601 ECU is still in there and works. I wonder what the differences really are between them considering the auto ECU works in my manual-swapped car...

Edited May 4May 4 by chaseincats