P0604

2ZR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0604: Random Access Memory (RAM)

DTC P0604 - Random Access Memory (RAM)

MONITOR DESCRIPTION

The ECM continuously monitors its internal memory status. This self-check ensures that the ECM is functioning properly. It is diagnosed by internal "mirroring" of the main CPU and sub CPU to detect the Random Access Memory (RAM) errors. If outputs from these CPUs are different and deviate from the standards, the ECM will illuminate the MIL and set the DTC immediately.






MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





INSPECTION PROCEDURE
HINT: Read freeze frame data using a Techstream. Freeze frame data records the engine condition 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.

PROCEDURE

1. READ OUTPUT DTC (DTC P0604)
(a) Connect a Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the tester ON.
(d) Clear DTC DTC Check / Clear.
(e) Turn the ignition switch to OFF and turn the tester OFF.
(f) Disconnect the tester.
(g) Disconnect the cable from the battery negative (-) terminal and wait for 1 minute.
(h) Connect the cable to the battery negative (-) terminal.
(i) Connect the tester to the DLC3.
(j) Turn the ignition switch to ON.
(k) Turn the tester ON.
(l) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
(m) Read DTCs.
Result:






B -- REPLACE ECM
A -- CHECK FOR INTERMITTENT PROBLEMS