P0637
UniversalThe Power Steering Control Module (PSCM) has detected a voltage reading in the power steering control circuit that is higher than the specified normal operating range.
High SeverityThis code indicates an electrical issue where the Power Steering Control Module (PSCM) circuit is receiving an abnormally high voltage signal. This can lead to a loss of power steering assist, making the steering feel very heavy and difficult to turn, especially at low speeds.
⚠️ Before You Begin (Safety First)
Always wear appropriate personal protective equipment (PPE) when working on your vehicle. Before performing any electrical diagnostics or repairs, disconnect the battery's negative terminal to prevent accidental shocks or damage to electronic components. Be aware that loss of power steering assist can make driving dangerous and should be addressed immediately.
Common Symptoms
- Increased steering effort (heavy steering)
- Illumination of the power steering warning light
- Steering may feel intermittent or erratic
- Difficulty maneuvering at low speeds
- No power steering assist
Common Causes
- Open circuit or short to voltage in the power steering control circuit wiring
- Faulty Power Steering Control Module (PSCM)
- Corroded or loose electrical connectors at the PSCM or power steering motor
- Damaged power steering motor or sensor
- Internal fault within the electric power steering (EPS) rack or column assembly
- Issues with the vehicle's electrical system supplying power to the PSCM
Frequently reported on: Ford Escape (2008-2012), Chevrolet Malibu (2004-2012), Pontiac G6 (2005-2010), Toyota RAV4 (2006-2012), Nissan Versa (2007-2012)
Diagnostic Steps
- Inspect all visible wiring and connectors related to the power steering system for signs of damage, corrosion, or looseness. Pay close attention to connections at the PSCM and the power steering motor.
- Check relevant fuses for the power steering system in both the under-hood and cabin fuse boxes and replace if any are blown.
- If accessible and with appropriate wiring diagrams, use a multimeter to test for proper voltage and continuity at the power steering control circuit.
- Clear the code using an OBD-II scanner and test drive the vehicle in a safe area to see if the code returns or if symptoms persist.
- Ensure the vehicle's battery is fully charged and its terminals are clean and secure, as low voltage can sometimes trigger electrical codes.
👨🔧 When to Call a Professional
If you lack experience with advanced electrical system diagnosis or if basic checks do not identify the issue, it is highly recommended to consult a certified automotive technician. Steering system issues can severely impact vehicle safety.
Commonly Asked Questions
What specifically does the P0637 code indicate?
The P0637 code signifies that the Power Steering Control Module (PSCM) is detecting a voltage in its control circuit that is higher than the manufacturer's specified operating range, often pointing to an electrical fault.
Is it safe to drive with a P0637 code and no power steering?
It is not recommended to drive with a P0637 code if you are experiencing a loss of power steering assist. The steering will be significantly harder to turn, especially at low speeds, which severely impacts control and safety, particularly in emergency situations.
Could a P0637 code be caused by something simple like a fuse?
Yes, a blown fuse in the power steering circuit can sometimes lead to this code by disrupting the normal voltage flow, or a short circuit can cause a high voltage reading. It's a good starting point for diagnosis.
What is the typical cost to repair a P0637 code?
Repair costs for a P0637 code can vary significantly. A simple wiring repair might be inexpensive, but if the Power Steering Control Module or the entire electric power steering unit needs replacement, costs could range from several hundred to over a thousand dollars, including labor.
Beyond visual inspection, how can I further diagnose a P0637 code myself?
Advanced diagnosis often requires a multimeter and the vehicle's specific wiring diagrams to test voltage, resistance, and continuity in the power steering control circuit. This helps pinpoint whether the issue is with wiring, connectors, or the module itself. If uncomfortable, professional help is advised.