Code P0380 ?? Anyone have a 98??

[Zac6.5]

I just got scan tool and ran it on my 98 since the check engine light has been on for a few months. I first had the truck checked at a shop and the mechanic said it was something to do with the glow plugs so I replaced all of them and reset it. The check engine light came back on within minutes. The scanner is showing a P0380 (Glow Plug/Heater Circuit A). The truck runs and starts great. I have just made it a mission to figure out why the check engine light is on. I have been all over the motor and the only thing I have found is one unclipped connector coming from the glow plug controller. On the drivers side wire (coming from the glow plug controller) that later splits into 4 wires (to go to each glow plug on that side) there is a wire that is spliced in with a single pin connector. I can't find anything under the hood that the connector is supposed to connect to. Does anyone have a 98 6.5?
Thanks ahead of time.
:confused:

[derekja]

Hmm, not sure where that pin goes.

That DTC was the first one (and most persistent one) when I had my ground problems, though. I actually had two issues, the first you're unlikely to have, but there was a bad splice in the harness that someone else had obviously worked on at some point and left in a bad state. The other, which you should check because it seems to be pretty common, is the engine ground at the back of the manifold on the passenger side. The glow plug controller feeds into that ground and if it's dirty then you can start getting all sorts of weird codes. I wish I'd known that before I needlessly replaced my glow plug controller!

Hope you track it down...

[Zac6.5]

Thanks, I'll check all the grounds. Hopefully the harness isn't compromised.

[Zac6.5]

Okay both my battery grounds go to the front left and right bolts on the intake manifold. They are tight and pretty clean. After about 15 min of driving the blinkers get sluggish and sparatic. Batteries are good. Flasher was replaced, with no improvement. Would the voltage regulator cause that code. Autozone says the alternator is good. Any ideas?