No Response From PCM (SCI Only)

NOTE: After making any repairs, perform POWERTRAIN VERIFICATION TEST under VERIFICATION TESTS.

NOTE: With the DRBIII® in the generic scan tool mode, attempt to communicate with the PCM.

NOTE: If the DRBIII® can communicate with the PCM in the generic scan tool mode, it may not be necessary to perform this step.

Perform the symptom Checking PCM Power and Ground Circuits in the Driveability category. See CHECKING POWER & GROUND CIRCUITS under POWERTRAIN CONTROL MODULE in SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE. If the vehicle passed this test, go to the next step. If the vehicle did not pass this test, repair as necessary.
Turn the ignition off. Disconnect the PCM C2 harness connector. See Figure. Disconnect the DRB from the DLC. Measure the resistance between ground and the SCI Transmit circuit. If the resistance is below 5 ohms, go to the next step. If the resistance is above 5 ohms, go to step 4.

NOTE: If vehicle is not equipped with a TCM, repair the SCI transmit circuit for a short to ground.

Turn the ignition off. Disconnect the TCM harness connector (if equipped). See Figure. Measure the resistance between ground and the SCI Transmit circuit. If the resistance is below 5 ohms, repair the SCI Transmit circuit for a short to ground. If the resistance is above 5 ohms, replace the Transmission Control Module. See TRANSMISSION CONTROL MODULE under REMOVAL & INSTALLATION.
Turn the ignition off. Disconnect the DRB from the DLC. Disconnect the PCM harness connectors. Disconnect the TCM harness connector (if equipped). Turn the ignition on. Measure the voltage of the SCI Transmit circuit at the DLC connector (cavity No. 7). If the voltage is above 1 volt, repair the SCI Transmit circuit for a short to voltage. If the voltage is below 1 volt, go to the next step.
Turn the ignition off. Disconnect the DRB from the DLC. Disconnect the PCM harness connectors. Turn the ignition on. Measure the voltage of the SCI Receive circuit at the DLC connector (cavity No. 6). If the voltage is above 1 volt, repair the SCI Receive circuit for a short to voltage. If the voltage is below 1 volt, go to the next step.
Turn the ignition off. Disconnect the DRB from the DLC. Disconnect the PCM harness connectors. Measure the resistance between the SCI Transmit circuit and the SCI Receive circuit at the PCM connector. See Figure and Figure . If the resistance is below 5 ohms, repair the short between the SCI Transmit and the SCI Receive circuits. If the resistance is above 5 ohms, go to the next step.
Turn the ignition off. Disconnect the PCM C2 harness connector. See Figure. Disconnect the DRB from the DLC. Measure the resistance between ground and the SCI Receive circuit. If the resistance is below 5 ohms, repair the SCI Receive circuit for a short to ground. If the resistance is above 5 ohms, go to the next step.
Turn the ignition off. Disconnect the PCM C2 harness connector. See Figure. Disconnect the DRB from the DLC. Measure the resistance of the SCI Receive circuit between the PCM C2 connector and the DLC. If the resistance is below 5 ohms, go to the next step. If the resistance is above 5 ohms, repair the SCI Receive circuit for an open.
Turn the ignition off. Disconnect the PCM C2 harness connector. Disconnect the DRB from the DLC. Measure the resistance of the SCI Transmit circuit between the PCM C2 connector and the DLC. See Figure. If the resistance is below 5 ohms, go to the next step. If the resistance is above 5 ohms, repair the SCI Transmit circuit for an open.
If there are no possible causes remaining, replace and program the Powertrain Control Module. See POWERTRAIN CONTROL MODULE under REMOVAL & INSTALLATION.