NOTE to PM7-B020 owners: As this topic suggests, pin 31 of the MCU should be disconnected from the PCB before it is grounded to enable the external ROM chip. Failing to do so may result in solid CEL and intermittent ECU operation. This issue was found only on PM7-B020 and should be considered on other ECUs only if the normal "jumpering" doesn't work AND there are no faults in adding the socket. This should also not be a problem if you're adding a daughter-board for the MCU, but yet again, be careful.