most likely the gpcm. 6.0 glow plugs rarely fail. and when they do, it'll be one and one only. anytime you have multiple GP codes, it's usually gonna be the gpcm
just test resistance of the 2 glow plugs at their corresponding pins at the gpcm connector. see if they fall within spec.
but first, make sure the gpcm connectors are both seated and latched. very common for the locking tabs on the gpcm to break and the connector back out slightly. if so, you can run a zip tie through connector to hold it to the gpcm. just need to run a washer under each gpcm stud to space it away from the bracket to make enough room for the zip tie. otherwise, you could crack the mounting ears of the gpcm when you bolt it back down
Last edited by kaya@bernhausen; 02-01-2013 at 10:24 PM.