P1604

Diagnostic Chart:

Engine Controls Schematics: MIL, Data Link Feed:

CIRCUIT DESCRIPTION
The PCM uses the class 2 serial data circuit to communicate with various other devices and systems in the vehicle. The PCM ensures that communication remains established by monitoring the class 2 serial data circuit for state of health messages from the other devices using the circuit. If the PCM detects a loss of the state of health serial data message from the IPC, DTC P1604 will be set.

CONDITIONS FOR RUNNING THE DTC
^ The ignition is ON.
^ The system voltage is more than 8.2 volts.

CONDITIONS FOR SETTING THE DTC
^ The PCM detects a loss of serial data from the IPC.
^ The above condition is present for longer than 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ The PCM stores the conditions that were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear Information function or by disconnecting the PCM battery feed.

DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions:
^ Intermittent short circuit on the serial data circuit - Refer to 220 Cell 50: Serial Data Class 2 and check all related wiring for an intermittent short to ground or short to voltage.
^ A faulty connection - Inspect the PCM and the affected control module harness and related connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Use a corresponding mating terminal to test for proper terminal tension.
^ A damaged harness - Inspect the wiring harness for damage. Check for an intermittent short or open circuit in the wiring harnesses related to the affected control module, including the ignition positive voltage, battery positive voltage, ground, and serial data circuits. Refer to Wiring Repairs in Diagrams.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.