Technical Description of OBD-II Trouble Code
Code for Controlling Power Steering
What does that signify?
This is a generic diagnostic trouble code (DTC) for the power steering control circuit. It is applicable to many OBD-II vehicles manufactured from 1996 onwards, including Saturn, Renault, Dodge, Ford, Nissan, Mercedes, and others. The exact repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
OBD-II trouble codes P0635, P0636, and P0637 are associated with the power steering control circuit.
When the Power Control Module (PCM) detects improper signals within the power steering control circuit, code P0635 is set and the check engine light is illuminated.
The power steering control circuit is responsible for providing the appropriate voltage to various power steering components. The PCM monitors voltage signals from the power steering controller, sensors, and switches. These components ensure the proper fluid pressure within the power steering system, which is crucial for preventing damage to power steering components. The power steering control circuit allows the power steering system to adapt to different driving conditions and prevent stiff or erratic steering. This circuit alerts the PCM to possible issues that require immediate attention.
An electric power steering motor:
What is the severity of this DTC?
The severity of this code can vary greatly. It can range from just an illuminated check engine light on a vehicle that operates normally to a stiff or erratic steering issue. Steering problems can become a safety concern if not addressed promptly.
What are some of the symptoms of the code?
Symptoms of a P0635 trouble code may include:
What are some of the common causes of the code?
Causes for this P0635 code may include:
What are some P0635 troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins (TSB’s) for the specific vehicle by year, model, and power plant. This can save a lot of time in the long run by providing guidance in the right direction.
The second step is to check the power steering fluid level and inspect for possible leaks that could affect the pressure supplied to the power steering controller and associated components. Proper fluid pressure is crucial for the functioning of this circuit. Then, locate all the components within this circuit and visually inspect the associated wiring for any obvious defects such as scraping, rubbing, bare wires, or burn spots. Next, check the connectors for security, corrosion, and damaged pins. This process should include the power steering controller, associated sensors, switches, and the PCM. The condition of the Controller Area Network (CAN) is important in this troubleshooting process, as a damaged wiring harness makes it difficult to pinpoint defective components.
Advanced Steps
The advanced steps are specific to each vehicle and require specialized equipment for accurate performance. These procedures involve using a digital multimeter and referencing the specific technical information for the vehicle. The voltage requirements will vary based on the specific year and model of the vehicle.
Voltage Checks
Specific troubleshooting guidelines must be referenced to determine the required voltage ranges within the power steering control circuit. Depending on the configuration, several power steering components are involved. Power steering controllers, pressure switches, and position sensors require different voltages to function properly based on the specific vehicle.
If this process identifies the absence of a power source or ground, continuity testing may be required to check the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power removed from the circuit, and the normal readings for wiring and connections should be 0 ohms of resistance. Resistance or no continuity indicates faulty wiring that is open or shorted and must be repaired or replaced.
What are some common repairs for this code?
Note: Code P0635 can often interfere with proper communication of a control module, leading to the triggering of other trouble codes. CAN issues can be difficult to pinpoint, resulting in misdiagnosis in some cases.
We always recommend seeking professional service to resolve this issue. However, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to function. If you are interested in this option, please upload your ECU file to our portal.
