F-350 in sig. Ok, I've been putting up with this code and a couple GP codes forever. Changed GP's back in december (injectors and UVC harnesses at same time) and was bummed to continue getting codes. It finally got to where truck was hard to start so I replaced GP controller yesterday and damn code came up again!! Just P0683 this time. Truck starts fine cold now though...

I did notice one of the pins on controller harness looked like it had been hot, slightly melted around pin. Could this be the problem??

 

Are you clearing them each time?

 

Here's what the book says

QB11 CHECK FOR DTC P0683
DTC P0683 is set when the PCM detects an open or short to ground or power diagnostic line.
Possible causes:
open diagnostic line
diagnostic line shorted to ground or power
faulty PCM circuit
faulty GPCM circuit


It sounds like you're on the right track with the melted part around the pin.

 

Thanks. I guess I need to find out what the suspect pin does. Hopefully? it has just gotten hot and 'moved' a little and no longer makes good contact?? Maybe I can tweak that pin a little and make better conection... I'll try to get a picture of it.

I also need to find out why my signature info keeps disappearing!? This will be 3rd time loading one up. Any Ideas?

Truck is an '01 F350 DRW 4x4 7.3 - sold as cab chassis truck (same frame as 450/550) I think the stupid, I mean 'smart', fancy glow plug controller is a California thing. I would have been FINE with a simple solenoid relay instead. Do people really just change one GP when this fancy thing tells'em one is bad? Or am I the only moron who procrastinates until a few die before replacing them ALL. I can't see tearing down to that point and only doin' one!! Hell, I changed UVC harnesses 'cause I don't have time to do stuff like that 'later'.

Oh, I bought a Scangauge II partly because of SES induced by GP codes. I wanted to be able to tell if something else was causing codes and I got tired of using friends' scan tools and/or having auto parts scan it. Yes, I generally clear the code when it comes up. At first it was like once a month, but had progressed to every other day recently - so I FINALLY got a GP controller, CERTAIN my SES problems would stop!

 

I think you have to have 26 posts before the signature line is enabled, so you need to think of a few more things to say. I believe the restrict posting pictures until the 26th post also.

We are talking about a truck equipped with a glow plug control module (as in CA emissions) and not the glow plug relay right?

 

Yes, I have the $120 controller (at powerstrokeshop.com) - not the MUCH cheaper (and probably more reliable ) GP relay.

I was coming back to this thread after using SEARCH and FAQ to answer the sig question myself. Thanks for being SO FAST that ya beat me to it!

Yes, after 25 posts sig line is enabled! - just a few more... hehehe, I've never really paid attention to my post count before! I read WAAAAAY more than I post.

I guess I was confused about sig thing 'cause I was able to load it and it was there for first several posts!

 

I also noticed I got a rep! Cool, I've been wondering how that worked... I guess a bit more searchin' is in order!

 

You'll start to feel more comfortable here as you hang around more. Remember there wouldn't be anything to read if no one posted something.

Chip in when you know an answer, and don't be shy about asking questions when you don't understand something. This is one of the friendliest places around, and no one will treat you bad for asking what might sound like a simple question.

There's also lots of good information here so remember to bookmark the things you think might be useful in the future. Here's a picture that you might want to have a look at for your GPCM.

 

The scale up in the upper right hand corner of the box, click on that and you will be able to add to the rep of the poster. You can also give them a negative rep. Rep points are worth nothing, they just mean that someone liked what you had to say, or something like that.
Also, if you become a supporter the sig line and pic posting is enabled right away.

 

So looking at the old GP controller, I see it is Pin # 3 above on both plugs that appears to have gotten HOT. The plastic is a bit melted at base of pin. The harness side was similar. Looks like 12v supply(s)...

It was hard to start again this AM - P0683 and (2) P0000, same as before. Took 2 tries, if it doesn't start right up I just cycle the GP's again. Must've been a little warmer yesterday AM.

I guess a FUSE check may be in order next!

 

Here's a little bit better diagram. It does appear pin 3 is the power lead that has an inline fusible link. You should be able to check voltage at pin 3 to ground and see if you have voltage present. I'm not familiar with the GPCM, but I imagine the power should be hot at pin 3 with the key off. I believe the PCM will control the gound circuit to complete the current and energize the glow plugs. You should be able to verify this with a volt meter. Just remember to check the circuit with the key off. The GPCM sends a 115v 10 amp current to energize the glow plugs and you don't want to be holding any metal prongs poking around at things with that current.

 

Thanks Chris.

I finally finished the Excursion project (for now), so its time to revisit this problem. If I don't plug in for a couple hours - truck barely starts (after a few cycles of GP's...) And thats at 50+ degs!!

Where are the fusible links?

If several GP's had failed, would that cause these fuses to blow?

 

The GPCM is supposed to set a code for each bad glow plug so you don't have to try and find them yourself. You could unplug the 9 pin connector, or the connector at the GPCM, and OHM the glow plug wires. You should see a resistance between 0.6 and 2 ohms for good glop plugs. If you unplug the flat 9 pin connector at the valve covers, the glow plug wires will be the outside 2 left pins, and the outside 2 right pins. Place the other probe from the meter on the center pin to get your readings.

I'll have to look for the fusible links, but I don't think a couple of glow plugs would burn them out. I don't think the links are between the GPCM and the glow plugs.

 

Let me clarify what I've done. I began getting GP codes last summer. I think it ended up being a couple on each head. It was summer and I was planning to swap injectors soon, so I put it off. At Christmas I replaced GP's, injectors (LOVE the Swamp's singles, btw!), UVC harnesses and a few other things. Truck would NOT start cold before GP's. After GP's, etc it worked great, although I got a P0683 every once in a while. Did a bunch of reading and learned many had to replace the GP controller to get rid of the code. Well, truck still started fine, so I didn't bother. The ScanGauge II makes it easy to check/clear codes so I knew I had no other codes (or SES lite would make me nuts!).

Truck slowly got hard to start cold again - So, I replaced GP controller. Now it is hard to start AGAIN.

 

Maybe something as simple as weak batteries. Have them load tested before you spend too much time on it.