like new to weird-like dead; help

[yellow3800]

Here's the situation that I need help with:

My 89GT ran like new one day, no engine codes, A/C works... like new

it slept.  I slept.

next day after starting and driving it, I noticed that the speedometer/odometer stopped working.  Throughout the day the engine started running gradually worse, to where now, after it cooled of and restarted, I don't feel safe driving it.  The A/C clutch won't engauge.

IT WON'T GO INTO DIAGNOSTIC MODE.

The car is very clean, all connections fine.  Computer gnds and pwr all check SOLID.

WHAT IS IT?

I noticed on the computer it has to be the second one.  "OEM REMANUFACTURED" is a blu/wht sticker slapped on the mem-cal after lid removed.

Maybe the car eats computers!  I am also told that on the sticker that any circuit with

[Mr. Beefy]

If you jump the 2 top right ports it should go into diagnostic mode(code 12) if the SES light is functional. You tried that and it does not work? Is the SES light functional?

[yellow3800]

no diagnostic mode.  Verified SES light works by checking pin on computer to gnd manually.  So the light works!  There is no change by jumping ports A and B.  

ALL WIRES IN THIS RELATED CIRCUIT CHECK FINE.  all gnds and pwr at computer check fine.

oh, and I forgot... like a nissan with an unplugged temperature sensor, the car will turn on the coolant fan before and after start with key fwd and fan continues to run while engine is running.

[Money pit Beretta]

Just repalce the "chip".  The computer it's self should be fine. It sounds like it went into "limp home mode".

[yellow3800]

I've also heard to hit the computer too.  lol.  I removed and replaced the chip [same chip], removed the case, and even had a mechanic teacher tell me years ago to "flex" the board in my hands if I ever ran into this problem.  Flexing the board defies electronics in my mind.  Either way, none of these tricks worked.  

well, anyway, car is not driving.  Is there a way that I can have the computer tested, or test the computer somehow?


oh, I've also heard the opposite - that the computer board is bad and that the chip is good.  I'm not a parts replacer, and would like to narrow down the part before I replace it.  I'll even let this thread sit here for a while for comments.  


Andy
89GT

[Money pit Beretta]

Yes, the board can go out, but it's rare. Try a new GM chip. I lost mine in my 90GT and had the same loss of systems. It did start after that, but ran very bad.

[1988GTU]

I have had a computer go bad and when replacing it, it took two computers before I finally scored a good working one.  Also, check the fuse for the ecm.  If it popped, find out why and then replace the computer.

[yellow3800]

Is this a good time to explore aftermarket computer/chip/combos?  just for the necessity-like-fixing/upgrade reason to do so?  the car is not magical.  I sorta doubt too that anything else but stock will help gas mileage.  This 89gt 160k mi. and no oil drips!

I'll check that fuse, but I think its good after a quick glance at the panel earlier on.

Thanks, and I'll keep everyone posted if I get anything to happen.

Andy

[SuzukiGhostRider]

There are like 3 or 4 Beretta ECM's for sale on Ebay right now. Just look up Beretta and narrow your search from there in the Parts & Accessories section. GL

[yellow3800]

VERDICT IS IN!  

I'm not a parts replacer, and have to know what is wrong before replacing the computer board, or mem-cal, or both.

I remember our 2nd year mechanics teacher once saying "take the board out of the case and gently tweak it, side to side, in a warping motion"  Now c'mon, no amount of this will fix anything but maybe I misunderstood.  

After all grounds and pwrs checked out [car like new really great shape], I did this - with the power on.  SURE ENOUGH, THE SES LIGHT CAME BACK!  It also went out asap because I could no longer tell with the engine running if my flex-hold was working.  well, I tried starting the car with the board in the flexed position where ses light comes on and diagnostics could in fact resume if they were needed.  It ran well!  ... then quickly fell off again.  SO!  what are the odds of the mem-cal/e-prom gone bad vs the computer board [which houses the socket for the mem-cal anyway]?  

I guess the board just had enough and submitted itself to a mechanical breakage.  Cheap manufacturing?  ... of course for any business, it did its job because most people don't drive cars this old.  

Same answer as seen above: I'm going to buy another computer board, and x-fer the mem-cal chip to the new computer.
AT LEAST I KNOW WHY!


Thanks for the help guys!


Andy

[Money pit Beretta]

Great man, good to hear your back on the road.  

[Cliff8928]

I've had mine go out before.  It would actually kill the engine if i was on the throttle at all.  I would have to reach over and tap the ECM and it would be ok again.