reading block learn values from GM EFI systems?

[Ross Myers]

> Ross it would be very handy to be able to download these or go in and
> look at them.

Firstly, you need to know where the ECM starts (memory location) to store
the Cell values at in RAM for your application, once that is known you can
request them as follows....

For me, I use EFILive to send a Mode2 command (that I defined) to download
the Cell values.

Basically in Mode2, the ECM sends back the values of 64 memory locations
starting at the address defined by the command.

So for my application I send to the ECM - $F4,$58,$02,$00,$11,$A1

$F4 being the ECM I.D
$58 The message length
$02 The Mode Number ($02 = RAM Dump)
$00 & $11 is the start of the BLM Cells RAM address (0x0011)
$A1 the message checksum

The ECM will send back the values of the next 64 bytes incrementing from
location 0x0011,
Now, there is not 64 BLM Cells, so you only need to bother with the bytes
your ECM uses (21 in my case), I ignore the values of byte 22 and up..

Check with any training notes you have on your vehicle, GM usually describe
the BLM cells quite well, that way you can figure out which cell number
refers to which RPM/Load value.

Also, If you are unsure where they are, you could pull the ECM power then
download the RAM contents (again using Mode2) then see where a group of
128's ($80) are stored, they will be your uncorrected/reset Cells.

Also, Mode2 can be used to dump 'protected' aftermarket Memcals, but this
has already been covered in the past.

> Now I have to use diacom and try and hit all these cells to see where
> the values are.

Well, the Aussie Diacom version just plain sucks (160baud only), so I don't
know what your version is capable of, we never got a version that supported
8192 capable ECM's.

I don't know what program your ECM is running, but I'm sure the popular
disassembly's on the FTP site would show where the BLM cells are.

Make sense??
Ross Myers


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