Tell us and our members who you are, what you like and why you became a member of this site.
We welcome all new members and hope to see you around a lot!
I am a former mechanic who hasn't turned wrenches in a long time. I am now involved with fire investigation type work. Mostly car fires. My job is to figure out the origin and cause of automotive mechanical failures that led to fires. Most investigators do not consider (or haven't though of) probing the ECU as a valuable tools in the post fire investigation. My knowledge of OBD2 systems, suggests to me that most late model vehicle will save a DTC fairly rapidly if an open or short is detected in circuit wiring. I assume these DTC's are time stamped and include freeze-frame data on most newer vehicles. This knowledge (coupled with good wiring diagrams) may help a guy like me figure out where that first mechanical failure occurred.
Of course, there may be damage to the ECU from the fire to contend with. I am trying t5o develop a protocol for the retrieval of this data...and I am looking for you guy-ses knowledge and suggestions as to whether this seems possible.
So to accomplish my proposed data recovery.
(1) I will need a newer Scan tool (than my Ethos)...one that can retrieve pending codes and freeze frame data (in addition to DTC's).
(2) A breakout box (like GoDiag)
(3) a regulated (power conditioned) 12-volt power source.
(4) and possibly a USB programmer (software) that can read EEPROMs that are unsoldered from the PCB circuit board.
If the ECU is relatively undamaged, after a visual / internal inspection and cleaning, I might be able to do a bench scan (with a wiring harness connected to the appropriate pins)
If the PCB or internals appear internally discolored, damaged or shorted...
Then my recovery would require me to take one of the following approaches.
One option would be to dismount the appropriate EEPROM/ Flash chip from the damaged board and mount it onto a donor ECU to do the read. I don't particularly like this option as this would require me to buy and waste a new ECU every time.
The other option would be if there is some way to read the memory directly from the chip (either while it mounted to the circuit board - or off the board in some sort of programming adapter).
Does anyone think this might or might not work...and whether they data will be useful in determining what DTC code set first, chronologically ...can anybody suggest equipment or accessories to accomplish my objective. Lastly, is there a good source of information for the location of internal components in ECU's and what information is stored where (by the various makes and models)...Is this available on Alldata etc...or only a manufacturer type thing.
(Sorry for the rather long question)
Many thanks
Greg
Hey Greg, welcome to the forum!
Interesting concept. I like the idea, but I do see a couple problems at face value.
I'm stuck on the chicken-egg part of your idea.
Did the injector #1 short circuit code set because it was the circuit responsible for burning down the car, or did it set because the harness was melting together in a car fire?
Plus, I wish freeze frame data listed a date and time! It would be much easier in my job to have that knowledge, and no one is trying to one up me with insurance claims, lol.
There may be some manufacturers that include that info in the data, but I don't think I've ever seen a PCM that knows the date and time.
Also, from what I have gathered from my VERY limited eeprom research, there is virtually no information available from any source that maps out the location and function of board level components.
I do applaud your oitside-the-box-thinking on this one. Please keep us updated as you hone this procedure.
