The P1689 diagnostic trouble code (DTC) indicates a fault within the delivered torque circuit of a vehicle's powertrain control module (PCM). This means the PCM is receiving unexpected or incorrect data regarding the amount of torque being produced by the engine. This can lead to various drivability issues and potentially damage the engine or transmission if not addressed promptly. Accurate diagnosis and repair are crucial to restoring proper vehicle operation.
P1689 Fault Code Information
| Category | Description | Potential Causes |
|---|---|---|
| Basic Definition | Delivered Torque Circuit Fault: The PCM is receiving an implausible signal related to engine torque output. | Faulty Torque Sensor, Wiring Issues (shorts, opens, corrosion), PCM Failure, CAN Bus Communication Problems, Mismatched or Incorrect PCM Programming, Faulty Throttle Position Sensor (TPS), Faulty Mass Air Flow Sensor (MAF), Internal Engine Mechanical Problems |
| Symptoms | Noticeable issues caused by the P1689 code being triggered. | Check Engine Light (CEL) Illumination, Reduced Engine Power, Hesitation During Acceleration, Transmission Shifting Problems, Stalling, Rough Idling, Erroneous Torque Readings on Scan Tool, Limp Mode Activation |
| Diagnostic Steps | Key steps in diagnosing and repairing the P1689 code. | Verify the Code, Check for Related Codes, Inspect Wiring and Connectors, Test Torque Sensor, Test Throttle Position Sensor (TPS), Test Mass Air Flow Sensor (MAF), Scan for CAN Bus Communication Errors, Check PCM Programming, Perform Mechanical Engine Tests |
| Severity | How serious is the P1689 code? | Moderate to Severe: Can cause drivability issues and potentially lead to engine or transmission damage if left unaddressed. |
| Common Misdiagnoses | Incorrect identification of the root cause of the P1689 code. | Assuming PCM Failure Without Thorough Testing, Replacing Sensors Without Verifying Wiring Integrity, Overlooking CAN Bus Communication Issues, Ignoring Mechanical Engine Problems |
| Related Codes | Codes that may appear alongside P1689 and provide additional diagnostic clues. | P0100 (MAF Sensor Circuit Malfunction), P0121 (TPS Circuit Range/Performance), P0606 (PCM Processor Fault), U0001 (CAN Bus Communication Fault), Specific Transmission Codes Related to Incorrect Torque Input. |
| Affected Systems | Vehicle systems impacted by the P1689 code. | Engine Management System, Transmission Control System, CAN Bus Communication Network |
| Torque Sensor Types | Different methods used to measure engine torque. | Strain Gauge Based, Inductive, Capacitive, Calculated (Virtual) |
| Location of Torque Sensor | Where the torque sensor is physically located on the vehicle. | Integrated into the Transmission, Crankshaft Position Sensor, Camshaft Position Sensor, or Calculated within the PCM based on various sensor inputs. |
| CAN Bus Significance | The role of the CAN Bus in transmitting torque information. | The CAN Bus is a communication network allowing various vehicle modules to share data. The P1689 code can be triggered by a break in communication on the CAN Bus, preventing the PCM from receiving accurate torque information. |
| PCM Programming | The importance of correct PCM programming and calibration. | Incorrect or outdated PCM programming can cause misinterpretation of sensor data, leading to a P1689 code. Flashing or reprogramming the PCM with the correct software may be necessary. |
| Mechanical Engine Issues | Potential mechanical problems that can influence torque output and trigger P1689. | Low Compression, Timing Issues, Faulty Injectors, Vacuum Leaks. These problems can cause the engine to produce less torque than expected, triggering the P1689 code. |
Detailed Explanations
Basic Definition: The P1689 code indicates a discrepancy between the actual engine torque and what the PCM expects, signaling a problem in the torque delivery circuit. This circuit involves sensors and wiring that communicate engine torque information to the PCM. The PCM uses this information for various functions, including fuel injection, ignition timing, and transmission control.
Symptoms: The symptoms of a P1689 code can range from subtle to severe. The Check Engine Light (CEL) is almost always illuminated. Reduced engine power and hesitation during acceleration are common complaints. Transmission shifting problems, such as hard shifts or failure to shift, can also occur. In some cases, the engine may stall or idle roughly. Some scan tools may display erroneous torque readings. The vehicle may also enter limp mode, restricting engine speed and power to prevent further damage.
Diagnostic Steps: Diagnosing a P1689 code requires a systematic approach. Start by verifying the code with a scan tool. Check for related codes, as they can provide valuable clues. Inspect wiring and connectors for damage, corrosion, or loose connections. Test the torque sensor (if applicable) to ensure it's functioning correctly. Test the Throttle Position Sensor (TPS) and Mass Air Flow (MAF) sensor, as their readings are used to calculate torque. Scan for CAN Bus communication errors to rule out network problems. Check PCM programming to ensure it's up-to-date and correct for the vehicle. Finally, perform mechanical engine tests if other tests don't reveal the problem.
Severity: The severity of a P1689 code is considered moderate to severe. While the vehicle may still be drivable, the underlying issue can lead to further engine or transmission damage if left unaddressed. The reduced power and shifting problems can also compromise safety. Prompt diagnosis and repair are recommended.
Common Misdiagnoses: A common mistake is assuming PCM failure without thorough testing. Replacing sensors without verifying wiring integrity is another frequent error. Overlooking CAN Bus communication issues can also lead to misdiagnosis. Finally, ignoring mechanical engine problems that affect torque output can prevent proper diagnosis.
Related Codes: Several codes can appear alongside P1689. P0100 (MAF Sensor Circuit Malfunction), P0121 (TPS Circuit Range/Performance), and P0606 (PCM Processor Fault) are common examples. U0001 (CAN Bus Communication Fault) indicates a network problem. Specific transmission codes related to incorrect torque input can also be present.
Affected Systems: The P1689 code primarily affects the Engine Management System and the Transmission Control System. It can also impact the CAN Bus communication network, which is essential for communication between various vehicle modules.
Torque Sensor Types: Engine torque can be measured in various ways. Strain gauge-based sensors use strain gauges to measure the deformation of a component under load. Inductive sensors measure changes in inductance caused by torque. Capacitive sensors measure changes in capacitance. Some systems use a calculated (virtual) torque sensor, which estimates torque based on other sensor inputs, such as engine speed, throttle position, and manifold pressure.
Location of Torque Sensor: The location of the torque sensor varies depending on the vehicle. It may be integrated into the transmission, part of the crankshaft position sensor, part of the camshaft position sensor, or calculated within the PCM based on various sensor inputs.
CAN Bus Significance: The CAN Bus is a critical component of modern vehicle communication. It allows different modules, including the PCM, transmission control module (TCM), and anti-lock braking system (ABS), to share data. The P1689 code can be triggered by a break in communication on the CAN Bus, preventing the PCM from receiving accurate torque information from other modules. This can be caused by wiring problems, faulty modules, or network interference.
PCM Programming: Correct PCM programming is essential for proper vehicle operation. Incorrect or outdated PCM programming can cause misinterpretation of sensor data, leading to a P1689 code. Flashing or reprogramming the PCM with the correct software may be necessary to resolve the issue. This is typically done by a qualified technician using specialized equipment.
Mechanical Engine Issues: Mechanical engine problems can significantly affect torque output and trigger a P1689 code. Low compression, timing issues, faulty injectors, and vacuum leaks can all cause the engine to produce less torque than expected. These problems should be ruled out before focusing on electrical or electronic components.
Frequently Asked Questions
What does the P1689 code mean? The P1689 code signifies a fault in the delivered torque circuit, indicating the PCM is receiving incorrect or unexpected data about engine torque.
What are the common symptoms of a P1689 code? Common symptoms include a Check Engine Light, reduced engine power, hesitation during acceleration, and transmission shifting problems.
Can a faulty sensor cause a P1689 code? Yes, a faulty torque sensor, TPS, or MAF sensor can all contribute to a P1689 code.
Is the P1689 code a serious problem? Yes, it is considered a moderate to severe problem that can lead to engine or transmission damage if not addressed.
How is a P1689 code diagnosed? Diagnosis involves checking for related codes, inspecting wiring, testing sensors, and scanning for CAN Bus communication errors.
Can PCM programming cause a P1689 code? Yes, incorrect or outdated PCM programming can lead to misinterpretation of sensor data and trigger a P1689 code.
Conclusion
The P1689 "Delivered Torque Circuit Fault" code indicates a problem with the communication or measurement of engine torque within a vehicle's system. A thorough diagnostic process, including checking wiring, testing sensors, and verifying PCM programming, is crucial for accurate identification and resolution of the underlying issue to restore proper engine and transmission performance.