Technical Description of OBD-II Trouble Code
Performance Issue with Internal Control Module Ignition Coil Control
What is the meaning of this?
This generic powertrain diagnostic trouble code (DTC) is commonly found in many OBD-II vehicles, including those from Ford, Chevrolet, Toyota, Jeep, etc.
When a code P06D1 is stored, it indicates that the powertrain control module (PCM) has detected an internal processor performance error in the ignition coil control system. Other controllers may also detect this internal PCM performance error and store a P06D1 code.
Internal control module monitoring processors are responsible for various self-test duties and overall accountability of the control module. The PCM and other related controllers constantly monitor the input and output signals of the ignition coil control system. The transmission control module (TCM), traction control module (TCSM), and other controllers also interact with the ignition coil control system.
In OBD-II equipped automobiles, the ignition systems use high intensity sparks generated by battery voltage and tightly wound induction coils. The PCM controls the timing of the ignition spark (coil) using input signals from the crankshaft position (CKP) and camshaft position (CMP) sensors. In the coil-over-plug, distributor-less ignition system, each cylinder has its own ignition coil. Each coil is connected to the spark plug with a short plug wire or silicon boot.
A constant supply of battery voltage and a ground pulse from the PCM create the high-intensity spark required to ignite the spark plug of each cylinder.
Other ignition systems use coil packs that operate in a similar manner, except multiple spark plugs are fired from a single coil pack with multiple towers. In this type of system, multiple cylinders are fired in sequential order. This system typically uses longer high tension spark plug leads to transfer the high-intensity spark from the coil pack towers to each spark plug at the appropriate time.
With the ignition switch on, the coils/coil pack receive a constant supply of battery voltage. The ignition coil releases a high-intensity spark when it receives a ground pulse from the PCM.
Whenever the ignition is on and the PCM is energized, self-tests for the ignition coil control system are initiated. In addition to running internal controller self-tests, the controller area network (CAN) also compares signals from each individual module to ensure proper functioning of each controller. These tests are performed simultaneously.
If the PCM detects an internal discrepancy in the ignition coil control system processor, a code P06D1 will be stored and a malfunction indicator lamp (MIL) may illuminate.
Example photo of a PCM:
What is the severity of this DTC?
Codes related to internal control module processors should be considered severe. A stored code P06D1 could result in various drivability concerns.
What are some of the symptoms of the code?
Symptoms of a P06D1 trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P06D1 troubleshooting steps?
Diagnosing a code P06D1 can be challenging, even for experienced technicians. Reprogramming may also be necessary. Without the proper reprogramming equipment, it is impossible to replace a defective controller and complete a successful repair.
If there are ECM/PCM power supply codes present, they should be addressed before attempting to diagnose a P06D1.
Before declaring any controller defective, several preliminary tests can be performed. These tests require a diagnostic scanner, a digital volt/ohmmeter (DVOM), and reliable vehicle information.
Connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data. Record this information in case the code is intermittent. After recording the information, clear the codes and test drive the vehicle until the code is reset or the PCM enters readiness mode. If the PCM enters readiness mode, the code is intermittent and will be more difficult to diagnose. The condition that caused the P06D1 to be stored may need to worsen before a diagnosis can be made. If the code is reset, continue with the following preliminary tests.
When diagnosing a P06D1, information is crucial. Search for technical service bulletins (TSB) that match the stored code, vehicle (year, make, model, and engine), and exhibited symptoms. The right TSB may provide diagnostic information that can greatly assist in the diagnosis.
Use the vehicle information source to obtain connector face views, connector pin-out charts, component locators, wiring diagrams, and diagnostic flow charts related to the code and vehicle in question.
Use the DVOM to test controller power supply fuses and relays. Test and replace blown fuses as necessary. Fuses should be tested with the circuit loaded.
If all fuses and relays appear to be functioning properly, visually inspect the controller-related wiring and harnesses. Also check chassis and engine ground junctions. Use the vehicle information source to find ground locations for related circuits. Use the DVOM to test ground integrity.
Visually inspect system controllers for signs of water, heat, or collision damage. Any damaged controller, especially from water damage, should be considered defective.
If the controller power and ground circuits are intact, suspect a defective controller or a controller programming error. Controller replacement will require reprogramming. In some cases, reprogrammed controllers can be purchased through aftermarket sources. Other vehicles/controllers will require on-board reprogramming that can only be done through a dealership or other qualified source.
