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Home / DTC / P0637 — Power Steering Control Circuit High

P0637 — Power Steering Control Circuit High

Detailed page for trouble code P0637.

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22,491specific
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Code

P0637

Generic P — Powertrain

Power Steering Control Circuit High

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or shorted wiring in power steering control circuit (short to battery/ignition feed)
  • Corroded, loose or contaminated connector(s) at the EPS/control module/steering motor
  • Faulty power steering control module or motor driver
  • Blown or incorrect fuse or a faulty relay supplying the EPS control circuit
  • High battery/charging system voltage or poor ground connection
  • Aftermarket accessories tied into the steering power circuit

Symptoms

  • EPS/PS warning lamp or general vehicle warning lamp illuminated
  • Reduced, variable or lost power steering assist (heavy steering)
  • Intermittent assist or torque steer feel
  • Diagnostic trouble codes stored related to EPS or communications
  • Possible limp-home mode (limited assist)
  • Noise from steering column/gear when motor tries to operate

What to check

  • Retrieve freeze frame and all stored DTCs with a capable scan tool; note conditions when DTC set (key on, engine running, steering angle)
  • Visually inspect EPS module, motor, connectors and wiring harness for damage, melting, corrosion, pin push-out, water ingress or rodent damage
  • Check fuses and relays for the EPS circuit and any upstream power feeds
  • Measure battery voltage and charging system voltage with engine running and key on; verify within normal range (approx. 11–15 V)
  • Inspect and test ground points for the EPS/module for tightness and corrosion
  • Check for other module communication (U-codes) that may indicate network issues

Signal parameters

  • Battery/primary supply: ~11–15 V (key on/engine running)
  • Control/logic reference: typical 0–5 V range for low-voltage signals (varies by make)
  • PWM or drive duty: 0–100% depending on commanded assist (scan tool live data required)
  • Motor current draw: can range from ~1 A (idle) up to tens of amps under load — use a clamp meter or manufacturer data
  • Ground resistance at module:

Diagnostic algorithm

  1. Connect a diagnostic scan tool and confirm P0637; record freeze frame and related codes. Clear codes and attempt to reproduce.
  2. Visually inspect connectors and wiring at the EPS control module, steering motor, fuse box and battery for damaged insulation, exposed conductors, corrosion or signs of shorting. Repair as needed.
  3. Check fuses and relays in the EPS supply circuit. Replace any blown fuses and retest.
  4. With key ON (engine off unless instructed otherwise by manufacturer), back-probe the power and control pins at the EPS module connector. Compare measured voltages to expected values and look for a constantly high voltage on a control pin (indicating short to battery).
  5. Verify battery and charging system voltages. If charging voltage is excessively high (>15 V), diagnose charging system before EPS repair.
  6. Test module grounds: disconnect battery, clean and tighten ground connections, then measure resistance between EPS ground and chassis/battery negative (
  7. If a specific control/feedback circuit is high, isolate by disconnecting the EPS motor or a suspect connector and observe if the high signal clears — use caution and follow vehicle-specific safety steps when disconnecting live components.
  8. If wiring checks out, perform module bench or module-level diagnostics per manufacturer procedure (some modules require reprogramming or specialist test rigs).
  9. If module is confirmed faulty after wiring and power/ground checks, replace EPS control module or steering motor assembly with OEM part and program/configure as required.
  10. After repairs, clear codes and road-test to confirm the fault does not return. Re-scan for any related codes and verify normal assist operation.

Likely causes

  • Corroded or loose connector at EPS motor or module
  • Short to battery voltage on the EPS control/sensor circuit
  • Faulty EPS control module or motor driver
  • Weak/poor ground connection to EPS module

Fault status

⚠️ Status
Power Steering Control Circuit High — EPS control circuit voltage or signal above expected range detected. Verify wiring, power, ground and module before replacement.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

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Code

P0637

LAND ROVER P — Powertrain

Control Circuit of the power steering - high circuit

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or shorted wiring in power steering control circuit (short to battery/ignition feed)
  • Corroded, loose or contaminated connector(s) at the EPS/control module/steering motor
  • Faulty power steering control module or motor driver
  • Blown or incorrect fuse or a faulty relay supplying the EPS control circuit
  • High battery/charging system voltage or poor ground connection
  • Aftermarket accessories tied into the steering power circuit

Symptoms

  • EPS/PS warning lamp or general vehicle warning lamp illuminated
  • Reduced, variable or lost power steering assist (heavy steering)
  • Intermittent assist or torque steer feel
  • Diagnostic trouble codes stored related to EPS or communications
  • Possible limp-home mode (limited assist)
  • Noise from steering column/gear when motor tries to operate

What to check

  • Retrieve freeze frame and all stored DTCs with a capable scan tool; note conditions when DTC set (key on, engine running, steering angle)
  • Visually inspect EPS module, motor, connectors and wiring harness for damage, melting, corrosion, pin push-out, water ingress or rodent damage
  • Check fuses and relays for the EPS circuit and any upstream power feeds
  • Measure battery voltage and charging system voltage with engine running and key on; verify within normal range (approx. 11–15 V)
  • Inspect and test ground points for the EPS/module for tightness and corrosion
  • Check for other module communication (U-codes) that may indicate network issues

Signal parameters

  • Battery/primary supply: ~11–15 V (key on/engine running)
  • Control/logic reference: typical 0–5 V range for low-voltage signals (varies by make)
  • PWM or drive duty: 0–100% depending on commanded assist (scan tool live data required)
  • Motor current draw: can range from ~1 A (idle) up to tens of amps under load — use a clamp meter or manufacturer data
  • Ground resistance at module:

Diagnostic algorithm

  1. Connect a diagnostic scan tool and confirm P0637; record freeze frame and related codes. Clear codes and attempt to reproduce.
  2. Visually inspect connectors and wiring at the EPS control module, steering motor, fuse box and battery for damaged insulation, exposed conductors, corrosion or signs of shorting. Repair as needed.
  3. Check fuses and relays in the EPS supply circuit. Replace any blown fuses and retest.
  4. With key ON (engine off unless instructed otherwise by manufacturer), back-probe the power and control pins at the EPS module connector. Compare measured voltages to expected values and look for a constantly high voltage on a control pin (indicating short to battery).
  5. Verify battery and charging system voltages. If charging voltage is excessively high (>15 V), diagnose charging system before EPS repair.
  6. Test module grounds: disconnect battery, clean and tighten ground connections, then measure resistance between EPS ground and chassis/battery negative (
  7. If a specific control/feedback circuit is high, isolate by disconnecting the EPS motor or a suspect connector and observe if the high signal clears — use caution and follow vehicle-specific safety steps when disconnecting live components.
  8. If wiring checks out, perform module bench or module-level diagnostics per manufacturer procedure (some modules require reprogramming or specialist test rigs).
  9. If module is confirmed faulty after wiring and power/ground checks, replace EPS control module or steering motor assembly with OEM part and program/configure as required.
  10. After repairs, clear codes and road-test to confirm the fault does not return. Re-scan for any related codes and verify normal assist operation.

Likely causes

  • Corroded or loose connector at EPS motor or module
  • Short to battery voltage on the EPS control/sensor circuit
  • Faulty EPS control module or motor driver
  • Weak/poor ground connection to EPS module

Fault status

⚠️ Status
Power Steering Control Circuit High — EPS control circuit voltage or signal above expected range detected. Verify wiring, power, ground and module before replacement.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

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