P1601 BUICK, CADILLAC, CHEVROLET, GMC: SERIAL COMMUNICATION MALFUNCTION
POST UPDATED IN January, 2023
P1601 BUICK, CADILLAC, CHEVROLET, GMC: SERIAL COMMUNICATION MALFUNCTION
Serial Peripheral Interface (SPI) communication is used internally by the Engine Control Module (ECM). Through this, data is sent between the engine processor and the automatic transmission processor. A message checksum is included in each of the messages sent between the two processors. This value is compared with the calculated checksum. If some inconsistencies are discovered, the processor will check the new data and define it as corrupt and ignore the value. After this, the processor uses the previous message to notify the last message is corrupted.
The ECM often monitors the periodic status message from the TCM. If the message is not received, the fault counter has increments, and the P1601 OBDII fault code will be set.
Reasons to set the P1601 OBD2 DTC P1601 code:
Steps to troubleshoot the P1601 OBDII diagnostic code: