I don't plan on following up with this post with much more data, so please take it for what you think it's worth; I simply want to put it out there to save people some possible future headaches. Please don't be offended if you reply to this thread and I either avoid or simply don't reply to a question.

To any users of aftermarket flash programmers- If returning vehicle to stock for warranty/service repairs or diagnostics, I strongly recommend disconnecting the battery cables in conjunction with flashing the truck back to stock calibration. The Motorola MPC555 Processor contains 2 types of memory- FEEPROM and SRAM. Not all "freeze frame" and self-adaptive learning code is cleared from processor memory by reflashing the FEEPROM alone; disconnecting the battery terminals either directly before or directly after the return-to-stock flash will TOTALLY ERASE ALL PROCESSOR INFORMATION.

This applies for any performance device which loads via the under-dash Data Link Connector (in other terms, OBD-II port)

 

Nice job ......30 minutes long enough?

 

Anything over 5 mins will erase the KAM (Keep Alive Memory).

 

also turn the headlights on with the battery disconnected it will insure complete electrical drain.

 

The reason for the wait is due to the capacitors in the PCM discharging. If you disconnect the negative battery cable, and short it to the positive battery terminal, this should discharge these capacitors immediately.

 

Good idea.

These processors do not have the ability to write to thier own flash memory (and don't have allocated memory blocks to do so, even if they did), and have no "hard" method of storing data elsewhere (ie, hard drive, ect). Doing both the flash back to stock and clearing the KAM (SRAM) results in 100% erasure.

You can then procede to bending over as Ford's claims authorization officials pucker their lips (Unless you did something incredibly dumb along the way)

 

Hey Matt,

I don't know for sure, but I believe the processor is writing the FLASH device when an update is done. I don't think the FLASH device is accessible directly from the OBD-II connector.......

 

The erase of the flash is done directly through the data link connector, via a simple power pulse signal...As for the actual rewrite, you are correct, because the data is transferred over the SCP and CAN networks...so you are most certainly correct, there isn't a direct link.

I worded that last post a little funny and it did sound that way. What I meant to say was that the processor doesn't have any of the algorithms needed to transfer and store input data from sensors onto a memory block, and doesn't have a memory block allocated to store them even if it did. Hence the need for the "black box" plug-in datalogger Ford uses for diagnosis on troublesome trucks.

It would be in educated speculation that this will change next model year. But thats OK, because if it is written there is always some way to erase it

 

Really?? Wouldnt this cause sparks???

How long should I leave the battery disconnected with the headlights on?

And do we want to erase the KAM memory?

 

Don't forget, we have TWO (2) batteries. Both must be disconnected....Do NOT touch cables together with only ONE (1) battery disconnected. You WILL get lots of sparks!!!

 

Very good point!!!!!

 

Removing the battery cables and shorting them together is also stronlgy recommended prior to any arc welding on the vehicle. This eliminates any path for eddy currents/ground loops to send current where it shouldn't go....

 

So I guess Im reading this wrong, do you mean touch the two disconnected cables together? not touching the neg cable to the positive terminal on the BATTERY???

 

Exactly...

You just need to complete the circuit to drain the capacitor charge...

 

I would hate to know just how many warranty claims have been turned down by those three capacitors...