Nissan Repair: 04 XTERRA NO START,CODE P1605, fuel level sensor, air control valve

Question
I have a customer car towed in that will not start or turn over.  none of the dash lights work, also windows are inop.  The codes stored were: p1605=ecm/tcm communication signal malf; p0505=idle air control valve; p0462= fuel level sensor circuit low; p0328=knock sensor 1 circuit high. The radi and blower and headlights work.  supplied alternate power to battery and still no start.  Mainly worried about p1605 code and what to do next.

Answer
Jon,

Either someone jumped the car and connected the battery cables backwards and blew the ECM or even an aftermarket stereo amplifier was installed and did not have a good ground that that caused a backfeed that blew the ECM and related circuits.  I ahve had a truck that a customer did this to and I ended up replacing the ECM and every light in the vehicle that was on at the time of the overload/backfeed.  Now, you could disconnect the ECM and reconnect it, battery disconnected.  Then, reconnect the power and see if you get power.  Also, look at the positive terminal for blown fuse links and related fuses.  If all checks good and you still get the ECM code you know it is in need of replacement.  Once you have a good connection to the ECM then it is a matter of re-reading the codes and replacing other items that show back up.  One last thing you should do is try a different scanner as some do not like to interface with certain vehicles.  If you have a CONSULT II or a CONSULT III you will not have this problem.  I have several different scanners and some work and some give errors.  That could be the case as well.  And, I have even had ones where the vehicles OBDII connector was damaged and pins were pushed back where it would not make good contact with the scanner.  Email me back and let me know what you find.