To diagnose issues with the 3.0L engine ignition system, begin by removing the ignition coil cover and detaching the electrical connectors from all six ignition coils. With the ignition switch in the ON position, measure the voltage at the black/yellow wire for each connector; if voltage is present, proceed, but if not, repair the open circuit between the ignition coil and fuse No. 11 in the left side under-dash fuse panel. Next, turn the ignition switch OFF and check for continuity between the black wire and ground; if ground is present, continue, otherwise repair the open circuit between the ignition coil and the body ground. Detach the 31-pin connector from the Powertrain Control Module (PCM), ensuring the locking tab is on top, and check the specified wires for continuity to ground; if continuity is absent, proceed, but if present, repair the short in the wire between the PCM and the ignition coil. Reconnect the PCM multi-plug connector, and with the ignition switch in the start position, check for voltage at the multi-plug connector for each ignition coil; if the measured voltage is 0.5 volts, replace the ignition coil, but if no voltage is measured, repair the open circuit between the PCM and the ignition coil. For removal and installation, disconnect the negative battery cable, unfasten the retainers to remove the ignition coil covers, take off the multi-plug wiring harness from the ignition coil, unfasten the ignition coil mounting bolts, and then remove the ignition coil, installing in the reverse order of removal.