Nvram battery life

[Tony B.]

Been having sporadic Code 55 error from ECM (ECM Failure - check grounds. If good, replace ECM)

Engine will either run poorly, or start, then stall immediately.
Usually check things. Find nothing obviously wrong. Things return to normal and engine runs again.
On weekend, it did the start/stall thing and had to get towed home.
Next morning it started and ran fine for the next few days.... until today.

ECM won't even flash a Code 12 (that it is working)

Has the NVRAM battery finally died?

[vlad01]

Sounds like the ECU. Even without a memcal installed the ECU will still spit out a CEL and code, usually a memcal error code.

I had actually the same thing happen the year before in my daily, sporadic poor running and non starting, then randomly come good after a few min or hours. The clue was the ECU would not go into dia mode (no fan or CEL). I replaced the ECU with a new one, fixed the issue instantly.

I was going to get the old board repaired given the 808 is hard to get under a few 100 bucks now days, but it floated around in the car because I didn't have time from work and physically got damaged, had to bin it in the end.

The one I have in there now is a repaired unit, so hopefully it is problem free since one of the common issues has already been replaced.

[antus]

Yep ECM failure itself or NVRAM Battery failure (in which case, need to re-program replacement nvram chip in a programmer before putting it back on the nvram board and back in the ECM. Also check for corrosion around the ECM connectors, sometimes water gets and you end up with wiring problems at the connector that can show up as all kinds of errors.

[Tony B.]

Thank you Vlad and Antus...

After I posted, I went out and swapped in a spare 1227165 ECM with the VRAM board.
CEL acted normal and engine fired right up.
So something on ECM is suspect as suggested by you.

Did these ECMs have issues with cold solder joints? (what a nuisance to find/fix)
If so, I'd guess it may be right where the pinouts connect to the main board?
Ground and power pins may be the place to start - of course it could be any solder joint.

[antus]

Its not common but not impossible. Corrosion on the external part of the connectors is probably the main thing. I have seen 1 or 2 fail in strange ways though.

[delcowizzid]

The early boards the conformal coating bubbles up and breaks traces. quite often the cause of temp sensor circuit issues as well as other weird things. On another note my original nvram from version 1 probably the 3rd or 4th board ever sold just died haha

[Tony B.]

My celebration was premature.
Even with another ECM was back to NO CEL and start/stall problem in no time.

So problem must be within car wiring as Antus suggested.
I followed through the Factory Manual diagnostic chart, and while I found no "smoking gun",
the only thing it can be is intermittent contact in a connector on a ground pin to the ECM (CKT 450)

I cleaned it with Deoxit 5 and a brass brush and adjusted the terminal to "squeeze" the pin better when connected.
I reconnected the ECM and CEL light worked as it should, and engine started!!

Fingers crossed - I've solved the problem.
Thanks guys.

[Tony B.]

On another note my original nvram from version 1 probably the 3rd or 4th board ever sold just died haha

So how many years did the board's battery last?
Inquiring minds want to know.

[Gareth]

I have 2 that are used regularly that are 15 years +

[delcowizzid]

Well over the 10 years of rated battery life lol