P0635

Code

LAND ROVER P — Powertrain

Power Steering Control Circuit

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 20 EN: 36 RU: 16

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Page language: EN

Causes

Blown fuse or tripped relay for power steering/steering module supply
Poor battery or low system voltage
Damaged, corroded or disconnected connector(s) at the power steering/control module or motor
Open or shorted wiring (to ground or battery) in the power steering control circuit
Faulty power steering control module (steering ECU) or EPS motor/driver assembly
Internal motor driver failure or excessive motor current draw

Symptoms

EPS warning lamp or generic power steering warning on dash
Reduced or no power assist — steering heavy at low speeds
Intermittent loss of assist or assist cutting out during driving
Possible steering system limp/backup mode with limited assist
Related fault/information messages on the instrument cluster
Diagnostic trouble code P0635 stored in memory

What to check

Read and record freeze frame and stored codes with OEM-capable scan tool; check for related codes (modules, CAN bus)
Check battery voltage and charging system; ensure battery is fully charged and connections are clean/tight
Inspect fuses and relays for the steering module and motor (replace if blown)
Visually inspect connectors and wiring at the steering control module, EPS motor and junction points for corrosion, bent pins, damaged insulation or water ingress
Wiggle harness and connectors while watching live data and fault status for intermittent behavior
Check for other modules reporting communication errors (CAN bus)

Signal parameters

Primary supply voltage to steering control module: battery voltage (nominal ~12–14.5 V)
Reference logic supply (if present): typically 5 V reference for sensors/ECU inputs
Control signal to EPS motor: PWM output with variable duty cycle (0–100%) — duty varies with requested assist
Motor current: varies by assist demand; high/locked rotor will show abnormal high current
Circuit continuity: low resistance between module ground and chassis ground; no short to battery on control lines
Connector pin voltages and signal states should match OEM wiring diagram specifications (consult manufacturer data)

Diagnostic algorithm

Retrieve all codes and freeze-frame data; note any related network/communication codes.
Verify battery state-of-charge and charging system health; ensure stable supply voltage during testing.
Inspect fuses/relays and visually check connectors, seals and harness routing to EPS module and motor for damage or corrosion.
Back-probe power and ground at the steering control module; confirm battery voltage and good ground under load and with steering assist commanded.
With ignition on, monitor steering module live data (supply voltage, internal faults, PWM duty, motor current). Perform a wiggle test on harness while watching for code reappearance.
Perform continuity and resistance checks on suspect wiring between module and motor; check for short to ground or to battery on control lines.
If wiring and connectors are good, measure motor coil resistance and insulation as specified by the manufacturer; compare with service data.
If motor shows correct resistance and wiring is good but fault persists, consider steering control module or motor driver failure. Verify need for module replacement with OEM diagnostics and check for required programming/calibration.
After repairs, clear codes, perform health checks and road-test to confirm proper assist and that code does not return.
If intermittent or CAN-related, inspect vehicle network grounds and other modules for communication issues; address other stored U-codes as required.

Likely causes

Corroded or loose connector at the steering control module or electric power steering motor
Open/short in the harness caused by rubbing, pinch or previous repair
Blown fuse supplying the steering module or motor
Battery/charging system low voltage during diagnosis
Failed steering control module or motor driver unit

Fault status

⚠️ Status

Power Steering Control Circuit fault detected — check EPS module, wiring, fuses and motor for open/short or abnormal signals.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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