Corvette CCM Reverse Engineering Anyone?

[NomakeWan]

Had to get a little creative with jumper wires, but successfully communicated with my '90! I've dumped the CCM and attached it to this post.

From a quick glance, the VIN is in the same place, so it looks like we might be insanely lucky here; the fundamental stuff might just be shared between all CCM years.

For reference, my 90 has L98 engine, C68 HVAC, manual transmission, ABS, and the key is #11.

[-=Jeff=-]

I would like one quick clarification..

When Adjusting the EEPROM on the C4 CCM and we do the Hardware pin for programming, we only want that hardware jumper there for the programming process correct? then remove jumper before putting the CCM back int he car..

Also I assume we read the CCM, make changes, save the new BIN and program the New BIN into the CCM? through the Serial connection right?

[spfautsch]

The jumper wire is only needed to put the CCM in mode 5 (or 6, I forget) that allows uploading the necessary executable code to the module to erase / write the eeprom. I'll PM you though because I have a hack that makes them easy to re-program without tearing half your interior out.

Yes to your second question.

[spfautsch]

BTW steveo, if you're still following this you can keep the CCM I sent you. AngryCorvair hooked me up with an awesome donation. I'm almost done with my non-automotive side projects so will be ready to dive back into some ecmhack / 0411 goodness soon.

[In-Tech]

Just realized, that BIN dump si no good.. I forgot to do this:
go to Parameters tab -> Device ID and change the value from f4 to f1.

TY, yes that dump looked no bueno. I look forward to your next dump. I have no need for any of this at this time but I am following along eagerly :)

[steveo]

BTW steveo, if you're still following this you can keep the CCM I sent you. AngryCorvair hooked me up with an awesome donation. I'm almost done with my non-automotive side projects so will be ready to dive back into some ecmhack / 0411 goodness soon.

okay

if anyone from this forum needs a working CCM with unknown crap on the flash area and a mysterious jumper wire let me know

i just found one

[-=Jeff=-]

This one should be correct

Someone pleae tell me how to read the mileage, I know it is in HEX, but which byte is which, It doe snot match to what my ODO is showing.. but I might be doing it wrong

I think a couple flags might be wrong, but VIN is correct.

[-=Jeff=-]

looking at mine and NomakeWam's 90 CCM files. I don't think the Passkey addresses are correct. Also the flags I don't think are correct for the 1990.

I think the Passkey is at $B69F, I think the LT5 flag is at $B6CA as that is different between the L98 bin and LT5 bin.

These are guesses based on the relative location based on what I see in the thread. I will scan the others this weekend

Not sure the mileage is right on mine for some reason, but I will let you guys take a look

EDIT: I see Nomake's Passkey is 11

for my BIN, Vin is correct, I have a C60, ABS, 6spd and LT5. My Passkey is 14

looking at the hex code, my mileages is close

I think I found everything, but need a favor. I want to test the CCMs on the bench. HOw shall I wire up the RX and TX to the CCM for test

Thanks

[NomakeWan]

I think I found everything, but need a favor. I want to test the CCMs on the bench. HOw shall I wire up the RX and TX to the CCM for test

Thanks

GRAY Connector
C1 Ground
C11 Ground (when key is inserted into cylinder)

GREEN Connector
E4 & E5 +12V (when key is turned to run position)
E12 to F5 PASSkey Resistor Value (VATS)
F1 +12V
F12 ALDL

You were able to get your CCM downloaded, so I assume you have an ALDL cable you can use to talk to the CCM. Just connect the ground from your cable to the same ground as pin C1, and connect the ALDL data pin to pin F12. ALDL does RX and TX on one pin.

EDIT: It occurs to me that you should probably confirm those pinouts with an FSM for 1990 first. I don't have the electrical supplement for 1990 so I can't confirm that for you. The above pinout is correct for the 1994-1996 CCM.

[-=Jeff=-]

GRAY Connector
C1 Ground
C11 Ground (when key is inserted into cylinder)

GREEN Connector
E4 & E5 +12V (when key is turned to run position)
E12 to F5 PASSkey Resistor Value (VATS)
F1 +12V
F12 ALDL

You were able to get your CCM downloaded, so I assume you have an ALDL cable you can use to talk to the CCM. Just connect the ground from your cable to the same ground as pin C1, and connect the ALDL data pin to pin F12. ALDL does RX and TX on one pin.

EDIT: It occurs to me that you should probably confirm those pinouts with an FSM for 1990 first. I don't have the electrical supplement for 1990 so I can't confirm that for you. The above pinout is correct for the 1994-1996 CCM.

yes all the pins are the same. I have most of them through the years mapped and those specific pins are the same. not sure I know the PASSkey for all of them, but will try. I was hoping to use a serial dongle instead of rigging up the ALDL connector, but then I realized I have a scrap harness that I will extract the DIC, Cluster and CCM connectors and wiring to set up a mini bench. so the non- mounted CCMs will be a bit before I can read them.

any one have a 94 or 95 BIN they can repost for me to look at? thanks

[NomakeWan]

any one have a 94 or 95 BIN they can repost for me to look at? thanks

See attached.

As for the PASSkey thing, if you don't know it, all that should happen is your BINs will be missing the PASSkey information. The rest of the data should be intact.

[-=Jeff=-]

See attached.

As for the PASSkey thing, if you don't know it, all that should happen is your BINs will be missing the PASSkey information. The rest of the data should be intact.

But isn't the PASSkey Stored?

anyway, here is what I think is correct for the 1990 CCM for the flags, just based on relative locations between the 2.

[steveo]

the flash tool for these things never got well tested beyond my bench
definitely interested to see if it works for you

[-=Jeff=-]

the flash tool for these things never got well tested beyond my bench
definitely interested to see if it works for you

What wires did you have connected, meaning do I need to apply power to all the power pins?

[NomakeWan]

What wires did you have connected, meaning do I need to apply power to all the power pins?

You don't need to apply power to all of the pins as many of them are tied together internally. Please follow the pinout I posted a few posts ago.

But isn't the PASSkey Stored?

It is. But if the correct key is not "inserted" (that is, the correct resistance value is not applied between pins E12 and F5) then the CCM will not allow external devices to read those locations in memory. They will appear as blank data instead of the correct PASSkey data.