Corvette CCM Reverse Engineering Anyone?

[-=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.

[-=Jeff=-]

at this point, it is probably easier to work through my harness to get he wires I want as all the connectors are there..

[-=Jeff=-]

I am getting data on the serial bus but having this issue:

Reconnecting to ALDL bus, please wait....
ERROR! The bus is still noisy (retry)...
ERROR! The bus is still noisy (retry)...
ERROR! The bus is still noisy (retry)...
ERROR! Could not become the ALDL bus master.
ERROR! Error reading segment 0[40]
ERROR! Could not complete read procedure.

how do I get it not noisy?