My car was showing spanner light, took it in for diagnostic, had glow plugs it air dry) car still showing P0683 which means glow plug,general fault so a. 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. P1635 - Glow Device Circuit General Error Is this more than likely going to be the glow plugs? or could it actually be a wiring fault?
Glow device general error - agree, useful
What are the symptoms of a defective glow plug control module?
A diesel engine has one glow plug control module which controls the glow plugs. This means that you might not notice when a single glow plug goes bad as this only affects one cylinder in your engine. However, if two of three go bad or the control module itself malfunctions, you’ll quickly find it difficult to start the engine. In addition to watching out for the glow plug light on your dashboard, here are some common symptoms of a defective glow plug or glow plug control module:
- White exhaust smoke – a defective glow plug will cause diesel to leak into the exhaust where it burns.
- Hard to start – this could mean the engine is slow to start in warm weather or fails to start in cold weather. However, this can also be a symptom of a problem in the fuel system or battery.
- Poor engine power – after a difficult start, bad glow plugs will make it difficult for your car to run properly, due to improper combustion which reduces power and efficiency.
How can you test your glow plug control module?
First things first, is it a problem with your glow plugs or your glow plug control module?
The easiest is to check your glow plugs before testing your glow plug control module.
To test your glow plugs, simply connect a 12-volt test light to the positive battery terminal. Then disconnect the wires from each of your glow plugs and touch the probe of the test light to the terminal of the glow plug itself (not the wiring harness). If the light doesn’t light up, the glow plug is bad and should be replaced.
Easier is to use a professional glow plug tester device.
There is some discussion about whether you should only replace the glow plugs that have gone bad, or if it is best to replace them all. As one glow plug going bad could be a sign that the others will shortly follow, some experts recommend replacing them all at the same time while others suggest keeping a close eye on the remaining glow plugs.
If your glow plugs are all working correctly, move onto your glow plug control module. Start by checking the battery voltage to the glow plug control module, a voltage drop of over a half volt (or more) means your control module should be replaced.
How to choose the right glow plug control module?
As glow plugs and glow plugs control modules don’t come in a one-size-fits-all format, it is important to select the correct type for your car and the type of fuel that you use. Additionally, using premium components is recommended, as a low-quality part can cause expensive consequences for your engine. For example, a swollen glow plug constructed from sub-par materials would either be impossible to remove later or the tip would break off in the cylinder, causing damage to the cylinder, valve and head.
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.
Replace defective wiring rather than trying to handle it individually in the wiring harnesses.
Need help with a P0683 code?
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Error Code P0380: DTC Glow Plug/Heater Circuit “A” Malfunction
Error Code P0380 is defined as Glow Plug/Heater Circuit “A” Malfunction. Meaning, there’s a problem with the glow plug heater circuit of the vehicle, causing the vehicle to have difficulty in starting and exhausting smoke.
This code is a generic trouble code, meaning it applies to all vehicles made since 1996 up to present. Specifications on the definition, troubleshooting and repair of course, vary from one make and/or model to another.
For GM vehicles for example, the description is slightly different, which says: Glow Plug Performance Conditions.
This code is commonly found on Chevrolet, GMC, Volkswagen and Ford diesel-equipped vehicles. But they can be possibly found in other makes as well, such as Citroen, Saab, etc.
The Glow Plug works when starting a cold diesel engine. The PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) uses the coolant temperature when the ignition is switched on to determine the cold diesel engine. The Glow Plug then heats up (glowing) for a short period of time to increase the temperature of the cylinder and allow the diesel fuel to ignite more easily. If there is open in the circuit or in the glow plug, then the code P0380 is set.
Basically, the code refers to the fault in the glow plug/heater circuit “A”. Another Error Code which is very similar to this code is the P0382, which refers to circuit “B”. For vehicles with multiple codes, the best way to fix them is by the order they appear.
To reduce engine noise and smoke, some diesel engines operate the glow plugs for a period of time after the engine is running.
As with other error codes, the most common symptom of Error Code P0380 is the activation of the Check Engine light. Other symptoms include:
- Hard starting, especially on cold weather
- Glow plug/Wait To Start indicator remains illuminated longer than usual (may be on solid)
- Excessively noisy during start-up
- White smoke coming out from the exhaust
There are many things that can cause or trigger this error code, some of the most common causes include:
- Defective glow plug or relay
- Defective glow plug timer
- Defective glow plug module
- Open fuse
- Blown fuse in the circuit
- Corroded connectors, open wiring, or other faulty wiring or electrical connector issues
How to Check
As with other trouble codes, technicians diagnose this trouble code using the standard OBD-II trouble code scanner. They take note of the vehicle’s freeze frame data and use that information about the code.
They search for any additional codes present, as this code can be accompanied by other glow plug trouble codes.
Then, the technician will reset the trouble codes and restart the vehicle to see if the codes come back. If the codes DO NOT come back, that means the problem is intermittent, and the glow plug heater circuit is still working properly.
If the code comes back however, the technicians will then proceed to check the connectors, wire and fuses around the glow plug heater circuit. Any open wires, loose wires, damaged or corroded connectors, and blown fuses must be replaced.
After the replacement, the trouble codes must be once again reset and the vehicle must be restarted to see whether the problem is resolved or not. If the problem is still not resolved, then the technician will proceed on removing the glow plug A from its area and test it, along with the relay. If deemed defective, then it must be replaced. All remaining trouble codes present must be addressed accordingly as well.
How to Fix
Repairs for this error code are pretty simple and straightforward, some of the most common fixes are:
- Replacement of the faulty glow plug or glow plug relay
- Replacement of p=glow plug timer or glow plug module
- Repair or replacement of faulty or damaged connectors, wirings and fuses
This code is unlikely to cause the vehicle un-operational, but it can definitely make the engine run poorly.
Also, while blown fuses in the glow plug heater circuit is usually associated with the error code P0380, it can also be a result of a deeper issue. Blown fuses should be replaced as soon as possible. However, you should not always assume that it is the only cause of the trouble code.
Fault P0380 / P0670 Glow plugs
P0380: Glow plug/Heater, circuit A - malfunction (2.0 HDi engine)
This fault code does not light a lamp on the dashboard. It indicates a problem in the preheating circuit. This generic fault code does not specify the exact cause of the problem. The probable cause is a malfunction of the glow plugs themselves. They operate on a simple principle. They are comprised of a heating resistance which, when powered, will heat up the combustion chamber during the first seconds of engine operation to facilitate ignition (Pre-heating) and accelerate temperature rise in it (Post-heating).
They can be tested one by one, without necessarily removing them (Fig 2-1). Remove the connector or power wires and test them using a multimeter set to ohmmeter. They usually have a resistance of the order of 0.7 Ohm. Most multimeters are not accurate enough to measure this type of resistance. The display will show a resistance of 1 or 2 Ohm. This is enough to tell if the plug is working. Malfunctioning plugs have cut internal resistance (Fig 2-2 infinite resistance).
Go to the OBD2
P0670: Glow plug control module - malfunction (DCi engine)
Dci engines by Renault/Nissan will show a different fault code. Like for the P0380 fault code, the cause of the problem is not clear. The procedure is the same. First test the glow plugs. If they are in good condition, the second more likely hypothesis is a problem in the relay control unit which powers the plugs during pre/post heating. Using a multimeter set to voltmeter, test the voltage across the plug terminals during preheating.
P0683 - OBD Trouble Code
When a diesel engine is cold, the extremely high air temperature produced as the piston rises and compresses the air is quickly lost through heat transfer to the cold cylinder head. The solution comes in the form of a pencil shaped preheater known as a "glow plug." The glow plug is installed in the cylinder head very close to the point that initializes combustion, or the "hot spot."
This could be in the main chamber or pre-chamber. When the engine management computer senses the engine is cold through the use of its oil and transmission sensors, it makes the decision to assist the engine in starting with the use of the glow plugs.
OBD II fault code P0683 is a generic code that is defined as “Glow Plug Control Module to PCM Communication Circuit”, and is set when the PCM (Powertrain Control Module) detects a communication failure between itself and the glow plug control module. Note that this code applies only to applications with compression ignition (diesel) engines.
What causes this problem with the Glow Plug Control Module to PCM Communication Circuit?
Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors in the glow plug control system
- Low battery voltage(s)
- Use of often-substandard aftermarket glow plug control modules
- One or more defective glow plugs
- Blown fuses and/or fusible links in the glow plug control system
- Defective engine coolant and/or other associated engine sensors
- Glow Plug Solenoid failure
- Failed GPCM
- Defective or corrupted glow plug control driver(s) in the PCM
- Failed or failing PCM