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P0683 Glow Plug Control Module to PCM Communication Circuit

Check Engine Light

P0683 code definition

The P0683 code indicates that a diesel powered engine has an issue with the glow plug module communication circuit, which has been detected by the powertrain control module or another control module associated with the PCM.

What the P0683 code means

P0683 is a generic code for glow plug module encountering a communication circuit error, and can be detected by the PCM or the control modules for the transmission, ABS, instrument panel, body, turbo, anti-theft, cruise control, climate control, proximity alert, or traction control modules.

What causes the P0683 code?

Typically, this code is caused by:

  • Defective glow plug control module
  • Flaw in electrical connection
  • Wiring or connectors in the CAN bus harness that are open, shorted or corroded
  • A faulty driver in the PCM
  • Loose control module grounding strap or broken grounding wire
  • Defective CAN bus circuits

What are the symptoms of the P0683 code?

Usually, a P0683 code is preceded by the check engine light, though it can take up to eight cycles before it illuminates. The driver may complain of stalling, poor acceleration, white smoke from the exhaust, and a marked decrease in the vehicle's fuel efficiency.

How does a mechanic diagnose the P0683 code?

Diagnosing the P0683 has to begin with the CAN and the use of a Tech II or Authohex may be required for faster and more accurate diagnosis within this complex cluster of wires and harnesses. The memory within the PCM should be saved before beginning to eliminate the need to reprogram after repairs are done.

Using a CAN scanner will show the mechanic the pin values and how the control modules are operating without jeopardizing any of the individual units. The scanner will look at circuitry issues that occur while the vehicle is running. One-by-one tests of each circuit are not possible as there are thousands to test and any one could destroy a module if tested improperly.

The mechanic will also have to look for defective or disconnected system grounds as well as double checking that any transmission or engine grounding cables and wires are secure. All of the control module circuits must be tested for continuity with the battery ground. The mechanic will visually examine the electrical connections, looking specifically for corrosion or lose connections that increase circuit resistance, leading to code storage.

It is helpful to use the CAN bus system wiring diagram or pin out value chart for the vehicle, testing continuity between the individual controller connectors with a digital ohm meter and repairing shorted or open circuits as needed.

Common mistakes when diagnosing the P0683 code

Always diagnose codes in the order they have been stored to avoid unsuccessful repairs. Freeze frame data indicates the order that codes were stored, and only after preceding codes are addressed should you move on to the P0683 code.

How serious is the P0683 code?

The P0683 code is one that has a lot of room for misdiagnosis because everything from fuel injector codes and transmission codes to engine misfires and almost any other drivability code can be accompanied by this communication code. Proper diagnosis is important for eliminating the actual cause.

What repairs can fix the P0683 code?

The most common repairs for a P0683 code are:

  • Verifying the code with a scanner and a digital volt/ohm meter, however, an Autohex or Tech II may be necessary for the enormous amount of wiring to test for this repair. A CAN scanner really is the ideal solution here.
  • Inspect all wiring and connections, replacing or repairing anything that is corroded, damaged, shorted, open or disconnected, including fuses and components. Retesting after any repairs is necessary.
  • Once you have run a second scan, look at the control module ground circuits and test them for continuity with the battery ground, and be sure no system grounds are disconnected or defective.
  • Examine the CAN bus system diagram and pin out value chart and test controller connectors. What are the values from the manufacturer? Compare and then repair any circuits.

Additional comments for consideration regarding the P0683 code

Replace defective wiring rather than trying to handle it individually in the wiring harnesses.

Need help with a P0683 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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