GSIC - Global Service Information Center

### DTC P0604 Internal Control Module Random Access Memory (RAM) Error

### DTC P0606 ECM / PCM Processor

### DTC P0607 Control Module Performance

### DTC P0657 Actuator Supply Voltage Circuit / Open

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## DESCRIPTION

The ECM continuously monitors its internal memory status, internal circuits, and output signals sent to the throttle actuator. This self-check insures that the ECM is functioning properly. If any malfunction is detected, the ECM will illuminate the Malfunction Indicator Lamp (MIL) and set a DTC.
The ECM memory status is diagnosed by internal "mirroring" of the main CPU and the sub CPU to detect Random Access Memory (RAM) errors. The 2 CPUs also perform continuous mutual monitoring. The ECM illuminates the MIL and sets a DTC if one of the following occurs: 1) outputs from the 2 CPUs are different and deviate from the standards, 2) the signals sent to the throttle actuator deviate from the standards, 3) a malfunction is found in the throttle actuator supply voltage, of 4) any other ECM malfunction is found.

DTC No. | DTC Detection Condition | Trouble Area
P0604 P0606 P0607 P0657 | ECM internal error | ECM

## INSPECTION PROCEDURE

HINT:

  Reed freeze frame data using the intelligent tester. Freeze frame data records the engine condition when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

1.CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0604, P0606, P0607 or P0657)

Result:

  Display (DTC output) | Proceed to
  P0604, P0606, P0607 or P0657 | A
  P0604, P0606, P0607 or P0657 and other DTCs | B

| B |

GO TO RELEVANT DTC CHART

A |

CHECK AND REPLACE ECM