GSIC - Global Service Information Center

### DTC P0604/89 Internal Control Module Random Access Memory (RAM) Error

### DTC P0606/89 ECM / PCM Processor

### DTC P0607/89 Control Module Performance

### DTC P0657/89 Actuator Supply Voltage Circuit / Open

## for Preparation Click here

## 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 set the appropriate DTC and illuminate the MIL.
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 standard, 2) the signals sent to the throttle actuator deviate from the standard, 3) a malfunction is found in the throttle actuator supply voltage, or 4) any other ECM malfunction is found.

DTC No. | DTC Detection Condition | Suspected Area
P0604/89 P0606/89 P0607/89 P0657/89 | ECM internal error | ECM

## INSPECTION PROCEDURE

HINT:

  Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, 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 P0604/89, P0606/89, P0607/89, P0657/89)

1. Connect the intelligent tester to the DLC3.

1. Turn the intelligent tester ON.

1. Enter the following menus: Powertrain / Engine and ECT / DTC.

1. Read DTCs.

Result:

  Display (DTC output) | Proceed to
  P0604/89,r P0606/89, P0607/89 or P0657/89 | A
  P0604/89, P0606/89, P0607/89, P0657/89 and other DTCs | B

| B |

GO TO RELEVANT DTC CHART

A |

REPLACE ECM