Welcome to FTE Lamantler.
If you pull the other side, you will find the same problem.

 

I hate to resurrect this old thread but I am experiencing a similar GP/GPR/GPM issue. I have been living with a p0683 code for a while now. I didn't pay it too much attention since I hardly worry about the weather being cold enough to affect the truck...until last weekend when my X wouldn't start when up in the mountains in 30 degree weather/snow. I tried jumping the two posts on the GPR together and still no start. So i have been reading lots of different threads and I know my X is a CA truck and I believe I do have a GPM as well. So I am confused with what to test since the CA models seem to be quite a bit different. I bought a GP109 to test with - but in reading this thread, it seems it wont do me much good...Any suggestions?

 

The thing you tried jumping was the AIH relay and the GP109 won't do you any good. If you notice the rectangular box with 2 square plugs next to the AIH relay you tried to jump, that is your GPCM. P0683 indicates there's an issue with the GPCM, not the glow plugs.

Try unplugging one of the square connectors and see if that sets off a new set of codes. If not, the PCM is not talking to the GPCM.

 

So is there a way to test the GPCM? And I deleted the AIH...

 

Why did International shy away from the older style injector and glow plug setup where one could easily access everything w/o screwing around under the valve covers?

 

That would make life a LOT easier, which is probably why they did it .

Every time I remove a cover for any reason I always check the UVCH for any chafing. I've had them off twice (checking bolt torques and harness connection problems) and each time all the wires get a close inspection for even the slightest sign of wear. I'd rather find it in the driveway than on the side of the freeway.

 

Deleting the AIH won't really hurt you any. Most people just let the codes tell them when the GPCM is bad. I guess if you really wanted to you could play with a meter and jumper wires to be sure, but generally speaking the codes will tell you.


Changing over to the HEUI system had a lot to do with it. Get rid of the fuel injection pump and make the injectors fire off of engine oil from rails in the head and you've got to tweak a few things along the way.

 

Does any other injector lubricate via engine oil like the PSD? I assume the prolonged the life of the injectors by doing that?. I seems like the cost of the injectors increased by a factor of 5. Every time I see these posts I think I'm playing with fire not pulling my valve covers and refastening everything, checking all wires for chaffing, performing the 50 cent mod and retorquing the rockers.

 

Caterpillar developed the HEUI system for larger trucks, so yes, there are other injectors that use(d) engine oil for lubrication. I ran a fleet of Cat C-12 engines for years that use the same injector system. They never gave any trouble, even after 500,000 miles.

 

Well the only code I am pulling is P0683 - I am using a pretty generic scanner to boot.. In reading other posts in this thread, should I remove my valve covers and check all the UCVH's and re-torque the rocker arms as mentioned? Or is there a more specific code that the ECU will be throwing?