[RSLyrick]

Hey,

what makes you think that the ECM and CCM password exchange routine fails ?

If the FEDS is failing (Fuel Enable System), so this password exchange between the modules, you should get a DTC 54. Security lamp and SYS will also flash. Is this the case ? DTC 41 may be set as well .

If this safe communication fails, the fuel pumps are normally still getting primed but you will get no fuel injection so no start. Do you hear them running after ignition ?

Refer to 8D-62 for more details (about DTC 54) and 8D-54 (about DTC 41)

Do all the DIC classic bulbs light up after ignition before cranking ? (especially the SES light)

If you want to check the communication wires (UART), no need to dismantle the whole dash at the moment.

- Battery connected : check with a multimeter if you get 5V in the DLC (diagnostic) port at pin M, with ignition ON.

To check the second UART wire, same procedure, it could be probed at the back of the ECM (D15 and D20), same expected voltage value around 5V with key in ignition position.

That should help you check if you have a short to GND or 12V or something else.

For an open wire issue, it would be better to disconnect the battery, the ECM harness and CCM harness as well and do a continuity test with your multimeter between the ECM harness and CCM harness connectors.

You have to do this because two other modules (ABS, C68) are connected on this bus and they have all have (possibly) the capability to pull it to 5V, so you need to isolate the connection to these modules.