Power Steering Control Circuit High Voltage
The P0637 code indicates that the Power Steering Control Module (PSCM) has detected a voltage signal from the power steering control circuit that is higher than the manufacturer's specified range. This can be caused by a faulty PSCM, a short to voltage in the wiring or connector, or a malfunctioning power steering system component. The high voltage condition may affect the power steering assist, leading to increased steering effort or erratic steering behavior.
1. Most Common Causes
- Short circuit to battery voltage (B+) in the EPS control signal circuit
- Damaged, corroded, or pushed-back terminals in the EPS module connector
- Internally faulty electric power steering (EPS) module
- CAN bus wiring shorted to battery voltage
- PCM/ECU with internal control driver failure (rare)
2. Symptoms You Will Notice
- Steering wheel feels heavy or difficult to turn
- Power steering warning light illuminated on dashboard
- Intermittent or complete loss of power steering assist
- Steering wheel may vibrate or feel unstable
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for any related codes.
Step 2: Visually inspect the power steering control module and wiring harness for damage, corrosion, or loose connections.
Step 3: Test the voltage at the PSCM connector using a multimeter; compare with manufacturer specifications.
Step 4: If voltage is high, isolate the circuit by disconnecting components to locate the short to voltage.
Step 5: Replace the PSCM or repair wiring as necessary, then clear the code and test drive.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it may cause sudden loss of power steering assist, increasing the risk of an accident. Have the vehicle inspected immediately.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and minor repairs like cleaning connections, but could be higher if the PSCM needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.