89 ECU Fried - What can cause? Picture!!
 

Check out this picture. I was just driving around as normal and smelled the distinct burning electronics smell. Checked everywhere and did not see anything right off hand. My car went into "limp mode", with the check engine light on and fuel cut over approx 3000 rpm. I was able to get home ok. Checked for codes and none registered although the light was on. I could reset the ECU and make the light go off and it would go for about a minute like nothing happend then the light would come on and go into "limp". I checked the ECU and it is definitely fried as the pictures show. I have another one that I am about to put in but want to make sure whatever caused this to happen doesn't happen again. I'm cleaning up all the grounds around the ECU while I'm at it.
Has anyone experienced this? Did you find out what caused it or is it just something that happens every once in a while?

CRAP!!! I couldn't wait and just put the new one in. Within minutes I fried the new one in the exact same place! Now I've got to try to find yet another N353 ECU and do a better job troubleshooting before I fry another one. It's perfect convertible weather out there and I'm stuck in the garage!! Please help!!!

I'm guessing a bad OMP that is taking out the ECU as well.

Is your MOP working??? Its been a while since I looked at a S5 ECU, but that looks like the MOP controller and protective resistor.

Anytime the check engine light is on, you should be able to pull the codes.

my convertible has been inside for 1.5 years...theres some new paint under all that dust.

My verts been in the garage for about 6 months now. Im not to fimiliar with the ecu but if you could find out what blew i would trace it back, dreaded wiring diagrams, and look for a short in the wiring. best of luck. wiring is always fun. I thought a fuse would blow before the ecu. Have you installed any oversized fuses latly?

Damn! Thats the ECU I just sent you too huh? I hope you get this sorted out.

All those who said Oil metering pump look to be going in the right way. Terminal 3U on the ECU leads to the bad components that ICEMARK referenced, and the FSM says it's for the OMP. Why did I have to get so ANXIOUS!!!! I should have posted this earlier in the week when it happened and not when the UPS just dropped the replacement at my door. (Shout out to JUICEH for the fast shipping though!)
ICEMARK, do you have the replacement TMP4501 8-bit controllers by any chance? I know you can by them, but they are not programmed, correct? If so, I could I replace that and the resister that SHOULD HAVE saved me? Actually, this second time the microprocessor may not have been complete toast. It looks like it got hot, but didn't bake like the other one in the picture. The resistor is shot, so maybe it did it's job this time. Can you tell me the value it should be (color band is cooked) and maybe I can replace it and give it a shot after fixing my OMP issue.

ICEMARK, I did check the codes and it just blinked once and stayed solid. It never gave me a diagnostic code. I've done the procedure before so I don't think I did anything wrong.

Sorry, I don't have that chip. They are not programmed, you might try Digi-key. They have been able to find me some hard to get parts lately.

Since you have two ECUs, I'd check to see if you can pull out the same size resistor from one of the other boards. I don't have the value, most of the bigger resistors in the ECUs have just the value written on them.

And remember your MOP is wasted. Unplug and replace it before powering up another ECU

Thanks Icemark.. unfortunately both ECU's have the same resistor burnt out since it was burned out under the same conditions. Maybe someone out there has a ECU that they can open up and check? I believe this one has the value on it instead of the color bands.

what is it in that ecu that controls the fuel cut at 9k? also does anyone have a diagram of the s4 and s5 ecu's that show what does what?

i just opened up a 86 ecu, and its completly different, sorry i couldnt help you

did you just see the back side of a circuit board? There are two ciruct boards in mine and once you remove the outer panel you have to remove 6 screws on the circuit board and 2 on the side of the housing in order to remove the board.

Was it on a 89-91? If it was a pre-89 it won't have it since this is the control for the electric OMP.

It's the MOP for sure, too bad by design, they take out the ECU when they go. It goes to show you, that you need to find out what smokes an ECU before replacing it with another. They don't burn up by themselves.

Lesson learned...lesson learned. I really knew better. I don't know why I did that.

So does anyone have a S5 ECU they can open up and see what the value is of that resistor? The second ECU may be salvageable since I can get both parts. I'll paypal ya a few bucks if you send me a picture for your trouble.

pic of N350 but should be the same..

Hope it helps..


Gil

Gildardo, Thanks man!!! Great camera work too!! What's your e-mail and I'll paypal you a few bucks like I said I would for your trouble.

Dont worry about it... good luck to u..


Gil