DTC P1603: Pcm Internal Dual-Port Ram Communication, DTC P1604: Pcm Internal Dual-Port Ram Read/Write Integrity Failure Or DTC P1607: Pcm Internal Shutdown Timer Rationality: Testing

WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

Turn the ignition off. Disconnect the PCM harness connectors. Turn the ignition to run. Using a 12-volt test light connected to ground, probe the fused ignition switch output (Off-Run-Start) cavity C1-12 circuit at the appropriate terminal of the Miller Special Tool (8815). If the test light illuminates, wiggle the wiring harness to ensure that the problem is not an intermittent wiring problem. Does the test light illuminate brightly? If yes, replace and program the PCM. See PROGRAMMING . If no, check all related fuses. Repair the fused ignition switch output circuit.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.

Turn the ignition off. Disconnect the PCM harness connectors. With a 12-volt test light connected to ground and with Miller Special Tool (8815) installed, probe the (F11) fused ignition switch output circuit. Perform the above check with the ignition key in the off lock position, ignition on, engine not running position, and during cranking. Wiggle the related wire harness while probing the Miller Special Tool with the test light to try to interrupt the circuit. Does the test light illuminate brightly? If yes, go to next step. If no, repair the open or excessive resistance in the (F11) fused ignition switch (OFF, RUN, START) circuit. Inspect the related fuse, if the fuse is open check the circuit for a short to ground.

NOTE: Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.

Using the wiring diagram as a guide, inspect the wire harness and connectors. Visually inspect the related wire harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect both the component and the PCM connectors. The Powertrain Control Module is reporting internal errors, pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING .