Cummins ISB CM550 (1990-94) Fault Code: 364 PID: SID 233 SPN: 1077 FMI: 9 Engine Control Module (ECM) to Pump Communications Error

Circuit Description
This circuit is used to communicate fueling, timing, and pump status messages between the ECM and pump controller. If this link is lost, the pump will operate in a backup mode based on the idle signal (pin 4).

Component Location
The datalink is located within the ECM and fuel pump control module.

Shop Talk
1) The datalink is used to communicate fueling and timing commands, as well as pump status
messages. If the datalink is lost, the pump will operate in backup mode based on idle signal (pin 4 at fuel pump connector).
2) This fault code will be active if the fuel pump power supply is inadequate.
3) When troubleshooting for this fault, suspect that one or a combination of the following can be the cause: The ECM, fuel pump, or wiring harness/fuses/relay.