E34 is ignitioncircuit malfunction
P04 is ECM Communication error
F04 is ECM Communication malfunction
First thing i would check is that all the relays are seated good in their sockets pull them and push them back in tightly. Would also check the connector(s) going to the ECM to make sure they are tight,pull them also and plug it back in and make sure the latch is tight. Also check the alternator belt and load test the battery to make sure its ok