I randomly started throwing a couple codes that have been causing my "check engine" light to come on ... came on on my way into work this morning) . I know that the P0683 code is the Glow Plug Ctrl Module to PCM Comm Circuit (from my code reader), but I am not sure what to do next ... I have the dealer service DVD from 2002 that I will look at this weekend, just looking for some experienced tech guys to point me in the correct direction for risk and diagnosis. Thanks for the help!!!!

 

Well, if your GPCM is functioning ok, I'd check the wires and connection to make sure you're getting good continuity.

If your wiring harness and plug looks ok, you might need a new GPCM.

Stewart

 

has not thrown the code again ... I wonder if it could be due to my remote start ... I also had a security code thrown ... and the truck would not start with the remote ... I will keep an eye on it ...

 

From what I found out 95% of P0683 codes is the GPCM. I had the same issue. Swapped it and its gone. You can run the truck for a while with that code - especially since summer is coming. I did for about a year till I found a good deal on eBay. Napa wanted ~$200 for it! I was patient and got one off eBay for about $70 NIB. Partsguyed has it for $124.
www.partsguyed.com

 

Thank you for this post. Our F350 just threw a P0683 code. Current prices for the GPCM (California smog) modules in 2017 are ~$109

 

I had the same error code on my 2000 7.3, replaced the GPCM and that cleared the code.

 

Our 7.3L passed smog fine in 2012 & 2014, now having issues after a P0683 Code and GPCM replacement.

The rules changed allowing zero "monitor" discrepancies (Diesel Powered 1998 to 2006) after 2015,and read elsewhere 7.3L Drive Cycle Routine to reset the monitors.

"On May 4, 2015, BAR implemented OBD readiness monitor requirements on both the BAR-97 and BAR-OIS inspection systems.
A vehicle will not pass a smog check if it is:

Gas Powered: 1996 to 1999 with more than one incomplete monitor
Gas Powered and Hybrid: 2000 and newer with more than the evaporative system monitor incomplete
Diesel Powered: 1998 to 2006 with any monitor incomplete, or 2007 and newer with more than two monitors incomplete


On the TDS forum I found the following 2010 posting but not sure if it's relevant the new 2015 tests.

"1996-04 7.3L DIESEL

Description

Primary function of drive cycle procedure is to clear DTC P1000 and to satisfy specifications for SAE J1979. Each OBD-II monitor must run during drive cycle. If drive cycle has been completed and DTC P1000 is not cleared, repeat entire drive cycle. If a particular step is interrupted, repeat drive mode. If drive cycle is interrupted with a key-off, only drive modes that were incomplete must be run.

Performing Drive Cycle

1. Turn ignition on, but do not crank engine until WAIT TO START indicator turns off, or 10 seconds has passed (whichever is greater).

2. Start engine. Allow engine to idle with transmission in Park or Neutral for 40 seconds.

3. The following conditions must be followed to run certain OBD-II monitors that require engine to be under a load. On A/T models, select OVERDRIVE CANCEL to perform test in 3rd gear. On all models, turn on accessories (headlights, A/C compressor, blower fan, etc.). DO NOT use hazards or PTO. Select an uphill or level road. DO NOT select a downhill road. Driving downhill will unload engine and defeat test.

4. Accelerate steadily to 3rd gear (A/T) or 4th gear (M/T) and keep engine speed at 1500 RPM for 3 seconds. Accelerate steadily from 35 MPH to 65 MPH in about 15 seconds (A/T) or 11 seconds minimum (M/T). Repeat this procedure 3 times while maintaining conditions set in step 3) . Before proceeding, turn all accessories off and disengage OVERDRIVE CANCEL. On A/T models, go to next step. On M/T models, go to step 6.

5. On A/T models, drive vehicle in 4th gear continuously for one minute. Accelerate steadily from a full stop to 4th gear and then return to a full stop. Repeat this procedure 10 times, then go to next step.

6. Before continuing, use NGS tester and select EOT PID from PID/DATA MONITOR & RECORD menu. Ensure EOT PID value is more than 140°F (60°C). Allow engine to idle for 20 seconds in Park or Neutral. Turn ignition off. Start engine and allow engine to idle for 40 seconds in Park or Neutral. Repeat QUICK TEST in appropriate SELF-DIAGNOSTICS article. Drive cycle is complete.

7. If DTC P1000 is present after performing drive cycle, repeat step 4 maintaining a minimum MFDES PID value of 37 milligrams/stroke with engine speed at more than 1500 RPM for 11 seconds. Also, maintain a minimum MFDES of 37 milligrams/stroke with engine speed at more than 2300 RPM for at least 6 seconds. Repeat step 6. MFDES PID value must remain less than 12 milligrams/stroke for 11 seconds.

 

Got the 2002 F350 to pass California smog yesterday after replacing GPCM and running below ridiculous monitor reset regimen, to sell the vehicle to a grateful California buyer.

We believe the state (CA) is running these solid and desirable 7.3L diesels out of the state because they don't have diesel particulate traps and SCR DEF systems (The rules changed in 2015 allowing zero "monitor" discrepancies (7.3L Diesel Powered 1998 to 2006)).

Glad we made the decision to leave that state. This is sad.