P0677 - OBD Trouble Code

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The immediate signs of problem indicating OBD Error Code P0677 can the Check Engine Light On, increase in the fuel consumption, smoke from the tailpipe, reduced heat level indications, and engine stalling and not starting.

OBD-II Code Hard or no start in cold weather is defined as a Cylinder 7 Glow Plug Circuit/Open.

OBD P0677 code is a standard OBD-II trouble code that detects an issue with the glow plug circuit in cylinder 7. Each cylinder in a diesel engine has a glow plug, which is used to heat the engine and help ignition. The glow plugs are controlled by the powertrain control module (PCM), and when the PCM detects a voltage reading from the cylinder 7 glow plug circuit that deviates from the manufacturer’s specifications by more than 10 percent, the P0677 code will be triggered.

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.

What causes this problem with the Cylinder 7 Glow Plug Circuit?

• Faulty glow plug relays
• Faulty glow plug timer or module
• Defective glow plugs in cylinder 7, or possibly in another cylinder
• Defective electrical components in the glow plug circuit, including wires, connectors, and fuses
• Starter relay or glow plug relay failure
• PCM failure that might require reprogramming

1. Glow Plug - If the glow plug is faulty, it will affect the ignition problem and thus must be replaced immediately. Buy new glow plug now!
2. Glow Plug Connector - Inspect for faulty glow plug connector and replace them now, if found so. Buy new connector now!
3. Glow Plug Relay - Faulty relay will cause the ignition system to not function properly and thus might need immediate replacement. Buy new glow plug relay now!
4. Starter Relay - Faulty starter relay will lead to delayed engine starts and thus might need replacement. Repair or replace faulty component as required.
5. Engine Wiring Connector - Check for faults in relation to the wiring connector and thus replace it now!
6. Engine Control Module - OBD Error Code P0677 can be indicated by engine stalling or not starting, and check engine lights being on which can also be due to faulty ECMs. It’s better to get the faulty electricals replaced as soon as possible.
7. Powertrain Control Module - P0677 error code also relates to problems with the powertrain that is not able to generate response in time causing distorted engine timing. Find all the Powertrain related parts with us.
8. Diagnostic Tool - Detect the OBD error code by using professional diagnostic tools. Buy them from us now!

For us our customers are everything, and that’s why we will help you to diagnose P0677 code by mentioning some important symptoms below:

Common Symptoms

• Check Engine Light Illumination (or Service Engine Soon Warning Light)
• Lack/Loss of Power and acceleration
• Engine may be harder to start
• Engine hesitation and stalling

After you know the symptoms of your vehicle’s problem, it becomes easy to detect it and get started with solving it. So, next on our list is few common steps to correct this issue with your vehicle.

• Glow plug in cylinder 7 replacement
• Electrical components, wiring and connectors replacement
• Replacement of the glow plug timer or relay

To do all this, you will need few high-quality auto parts such as Glow Plug Relay, Glow Plug Timer, Electrical Component, Glow Plug Circuit, PCM, Engine, Starter Relay and so on. From where will you get them? From your local store? Well, why go there when you can order quality parts with us while sitting in the comfort of your home. So, just browse through our website and order your needed parts today.

This code is related to P0671, P0672, P0673, P0674, P0675, P0676, P0678, and P0679.

Here are some steps which you should follow in order to diagnose this fault code:

• Make use of a digital volt ohm meter (DVOM) for the complete test. Continue through the tests until the problem is confirmed. You will also need a basic OBD code scanner to reset the computer and erase the code.
• Check the glow plug by disconnecting the wire connector on the plug. Place the DVOM on ohms and place the red lead on the glow plug terminal and the black lead on a good ground. The range is .5 to 2.0 ohms (verify the measurement for your application by referring to a factory service manual). If it is out of range replace the glow plug.
• Check the resistance in glow plug wire to the glow plug relay buss bar on the valve cover. Notice the relay (looks like a starter relay) has a large gauge wire leading to a buss bar where all the glow plug wires are attached.
• Test the wire to the number one glow plug by placing the red lead on the buss bar number one wire and the black lead to the glow plug side. Again, .5 to 2.0 ohms with 2 ohms being the highest resistance. If it’s higher replaced the wire lead to the glow plug from the buss bar. Notice also that these leads from the buss bar to plugs are fusible links. Reconnect the wires.
• Check the same wires for looseness, cracks or missing insulation. Connect the code scanner to the OBD port under the dash and turn the key to the "on" position with the engine off. Clear the codes.
• Also check for faulty PCM and repair or reprogram it as required as it might be the reason for wrong codes getting stored in system.

Common Mistakes When Diagnosing the P0677 Code

The most frequently made error when diagnosing this code comes from failing to correctly follow the OBD-II trouble code diagnosis protocol. It’s important for mechanics to follow the protocol step by step, as this guarantees an efficient and thorough diagnosis. Timers and relays are regularly repaired erroneously, when the error is actually a defective glow plug, or faulty fuses, wires, or connectors.