Electronics are clearly NOT my specialty. MS was worky, now no worky.
 

As the title states, Electronics are not my specialty at all. I was working today to do a few things to the car. I was trying to get my cops running in sequential (Couldnt get spark in output test mode) Tried to get my variable tps to work. and finally I tried to get my fan control to work again. When I tried my fans, I was testing for voltage with the car on, I ended up accidentally touching the 12v in to the fan output, either that or 12v to IAC1B. Im not entirely sure which two touched, all I know is that two wires touched, and one of them was the 12v. heard a bit of a pop. and the MS shut down. The computer was connected at the time, and went offline as soon as this happened. I cannot get the computer to reconnect to MS.

The LEDs do not turn on currently. I am still getting 12v in at the harness. I pulled the ecu apart and see nothing blown, but I havent gotten the chance to check anything with a meter yet, mainly because Im not sure where to start.

Anyone have any thoughts of what to do or check?

Anyways, pics below:

https://www.miataturbo.net/attachmen...ine=1327882369

https://www.miataturbo.net/attachmen...ine=1327882369

https://www.miataturbo.net/attachmen...ine=1327882369

https://www.miataturbo.net/attachmen...ine=1327882369

https://www.miataturbo.net/attachmen...ine=1327882369

First see if you can connect with a laptop - getting the LED spark outputs working should be a bit further down on your priority list.

I can try again once I get back to the car. but at the time, I tried to connect to the ecu, and the laptop would not connect. When it happened the ecu was connected to the laptop, and TS went offline.

If it won't connect, first try reloading firmware.

Ok, The car is at my friends house, which I cant get to until tomorrow at the earliest. Are there any other things to check after trying to reload firmware, that way I have a list of things to check

Bump,

Anyone have any other suggestions, I haven't been to the car yet. but I don't want to go all the way to the car, just to try reloading the firmware and have it not work afterall. If there is a list of things I can check while im at the car, I feel like I would at least be able to narrow things down, in the event that the firmware isnt the issue.

Also Matt, Just to make sure we are on the same page, The car was running prior to this, I was mentioning the spark outputs because it was something I was messing with a few minutes prior to having issues. Mentioning the leds is just me saying that the leds that turn on when the ms is powered up arent turning on currently.

You can also try this voltage check to look for short circuits: power up the Megasquirt on a Stimulator or on the car and check the following points for voltage with a multimeter.

You should find the same voltage as the battery voltage on the following points: S12, S12C, the center legs of Q9 and Q12, the left (non-banded) end of D3, the left leg of U5, and the left (banded) end of D9.

You should have 5 volts at the following points: S5, the two +5V holes in the proto area, the right (non-banded) end of D9, the right leg of U5, the left (banded) end of D19, and pins 1, 20, and 31 of the CPU.

I do not, however, have a flowchart for how to follow this check up at present.

You need to mail the daughterboard to Peter Florance and give him lots of money to replace the CPU chip and the CANbus driver.

There's little doubt in my mind that you blew it.

Thanks matt! I will give that a shot as well!

Mine neither scott, but I want to be 100% sure before I take any action.

If you touched 12v to the wire going back to JS11, the cpu is fried.

It was JS0/IAC1A, If I recall correctly.

Regardless, Im going to do these tests just to make sure, And im taking my 1.6 injectors and ecu to get the car drivable at the very least.

If you touched 12v to pretty much any wires that directly interfaces with the CPU, the CPU is fried.

Unfortunately, microprocessors just aren't very tolerant of voltages higher than VDD on their I/O pins. This is why most (all?) of the external analog and switch-sensing circuits you see in the MS "hacks" section have series resistors and zener diodes in them- to protect the ECU from this specific condition.

This is pretty much what I was thinking as soon as I heard the little pop. The big thing I wasnt sure of was what component exactly would be taking the hit.
The good news is I have a few people local that possibly have spare daughtercards. I may just get one from one of them.

If that's the case I call dibs on the dead one :)

Would you really have a use for it?

Edit: Random thought, I cant find the little terminator plug for connecting to innovate (change back to narrow band signal for stock ecu) Does anyone have any experience with connecting to innovate with just the one connector and no terminating plug?

yeah, I'd buy a new cpu/canbus for it and try to repair it myself and then bribe Ken to load the boot on it.

Lars was telling me that one could do that, or send it to http://www.pftuning.com/

But he said that cost you quite a bit of money back when ms3 was brand new.
If I get a new board im sure we could figure something out.

Damn you. I wanted the dead one. :(

it goes to the highest bidder! :fawk:

lol.

in all seriousness, I cant find my damn terminator plug for the innovate and its pissing me off.....

Not sure if anyone noticed, but MOV1 looks pretty burnt! Isn't that what dumps the voltage in case of a surge?

I guess I'm not seeing what you're seeing? It looks fine to me.

The MOV is installed between +12 (where it enters the MS) and ground. It is in some ways similar to a zener diode, in that it conducts when the voltage across it rises above a certain threshold- approximately 22 volts in the case of this specific part.

Its purpose in this application is to protect the MS as a whole from overvoltage conditions on the main +12 line coming into the unit, such as might be caused by a glitch in the alternator's voltage regulation.

It will not, however, be in any way affected by the +12 supply coming into contact with the CPU. The presence or absence of the MOV does not affect the operation of the MS under "normal" conditions (when the +12 supply is not in an overvoltage condition). It does not conduct any current during normal operation, and is not in-line with the power supply.

based on what Joe P. said, no. the car was not running, and the battery was pulling 11.8v at the time.

Alright. Its dead Jim.

Everything on the mainboard checked out fine, I did have two questions about this though, a few components showed lower voltage. my voltage at the battery during testing was 11.8v
u5 was 10.5v
s12c was 10.9v
and d9 was 10.9v

Does this say anything or is the cpu dead?

After this I tried to load firmware, no dice.

Any thoughts before I throw stock ecu back in?

It's close enough.

Those three points should, in theory, all read the same, though slight variations are normal due to resistance in the probe. They key point is that they're within U5's operational threshold, and close enough to (battery - forward drop across D10) to be believable.

The most important test would be whether you have +5 at any of the various places where we expect it to live (such as the +5 hole near the proto area or pins 1, 20, and 31 of the CPU socket), but given your description of what happened, I'm leaning heavily in the direction of the CPU just being toast.

yeah, they were all like 4.95. so plenty close enough. I was thinking it was toast, Just wanted to make sure that the 10v was not an issue.

This is a problem with the Freescale microcontrollers. Atmel AVRs for example have a 5.6V Zener diode on ALL their input/output pins. I've never managed to destroy one, I wish I could say that for the HC9S12

That's who i suggested to you.

IIRC I was charged around $90 shipped to have mine repaired--the second time.

How quick was the turnaround?

within a week IIRC. He's in VA Beach, so quick deliver times.

cool, I emailed him this morning. Still waiting on a response, but we will see what happens between him and a friend of mine that may possibly have a card I can use.

Slight update on this, Still havent heard from him. and My potential sources for daughtercards came up dry. So im going to go ahead and get the one I have fixed. The stock ecu is back in the car and almost running, just need to hook up the wb with nb signal, and set base timing.

Another update, It lives! My only issue is that the tach does not work now, not entirely sure what the issue is. The car was running cops at one point in time, so therefore it has the resistor in the diagnostic box. I pulled that out to see if it made a difference, still no tach.