P1618

Circuit Description
The Serial Peripheral Interface (SPI) communication is used internally by the Engine Control Module (ECM) to send messages between the engine processor and the automatic transaxle processor. Included in each message sent between the two processors is a checksum of the message. Both the engine processor and the automatic transaxle will compare this checksum value with the calculated value. If the checksums do not match, the processor will view the new data as being corrupted and ignore the values. The processor will then use the previous message. The receiving processor will then send a message to the sending processor informing it that its last message was corrupted.

Conditions for Setting the DTC
- Battery voltage is greater than 9 volts for more than 2 seconds.
- Ignition ON.
- No ECM resets for more than 2 seconds.

Action Taken When the DTCs Sets
- The ECM will illuminate the Malfunction Indicator Lamp (MIL) the first time the fault is detected.
- The ECM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history will clear after 40 consecutive warm-up cycles without a fault.
- DTC(s) can be cleared by using a scan tool.