On my '02 Dmax the 0380 code was being set because the glow plug relay was "on" all the time. The voltage was above a certain level after the glow plug relay was commanded off and this is read as a 0380 fault. My dealer replaced the relay and the ECM because the relay was being held on at all times by the ECM as well. Hard to believe they both failed at the same time but I didn't care because the parts/labor were 100% covered by the 100,000 mile emmisions warranty. Don't pay a penny if you are under 100,000 miles.Any ideas of the first thing to check on code 0380?