How to check the electric power steering: full instructions

A sharp increase in steering effort when turning or a complete blockage of the shaft on the move are direct symptoms of system failure EPSrequiring immediate diagnosis. If you notice that the steering wheel has become “heavy”, there are jerks or extraneous sounds, you need to urgently check the electric power steering, as ignoring the problem can lead to an emergency. Unlike hydraulics, there is no liquid that can be added, so the primary diagnosis is based on the analysis of electrical parameters and reading error codes from the memory of the control unit.

Modern systems Electric Power Steering consist of an electric motor, gearbox, torque sensors and an electronic control unit (ECU). The check begins with a visual inspection of the wiring and connectors, as oxidation of contacts or rubbed wires are the most common cause of failures. Only by making sure that external circuits are intact can we move on to deeper hardware diagnostics using a multimeter and a specialized scanner.

Primary visual diagnostics and connector inspection

The first step in deciding how to check the electric power steering is a thorough inspection of the under-hood space and steering column. Often the problem lies in the banal oxidation of contacts or violation of the insulation of wires going to the motor. Pay special attention to the connector suitable directly to the body of the electric motor, as vibrations and temperature differences can disrupt the tightness of the connection. Damaged wiring can cause short-term shutdowns of the amplifier, which the system perceives as a critical error.

It is necessary to check the condition of the fuse responsible for the supply of the chain EPS. If the fusible insert has burned out, this may indicate a short circuit in the windings of the engine or in the wire harness. Replacing the fuse without eliminating the cause will lead to its re-burning, so it is important to find the source of the circuit. Visually assess the integrity of the corrugated wires running from the steering rack to the car body.

⚠️ Attention: Before starting any work with the electric part of the steering be sure to turn off the negative battery terminal. Failure to comply with this rule may result in short circuit or damage to the electronic control unit.

Check the attachment of the electric motor to the steering mechanism. Weakening of the mount bolts can cause vibrations that are transmitted to the steering wheel and perceived by the driver as a malfunction of the amplifier. Make sure that there are no traces of overheating or melting of plastic on the motor body, which may indicate an overload of the system.

Diagnostics with scanner and reading error codes

The most accurate way to understand the cause of failure is to connect a diagnostic scanner to the connector. OBD-II. Control unit EPS Stores a history of errors that will help localize the faulty node. Modern multi-brand scanners or specialized dealer devices allow not only to read the code, but also to view parameters in real time, such as power voltage and sensor readings.

When connecting, pay attention to the following parameters:

• 🔌 Voltage of the on-board network at the time of engine start (must be at least 13.5 V).
• 📊 Torque sensor readings (should be close to zero for straight wheels).
• 🌡️ Electric motor temperature (overheating can cause system shutdown).
• ⚙️ Vehicle speed sensor status (EPS does not work without a speed signal).

A common mistake is C1515 (torque sensor failure) or C1526 (EPS engine problems). If the scanner shows a communication error with the control unit, check the integrity CAN-buses. The lack of communication often indicates a line break or a malfunction of the ECU itself.

Checking electrical parameters with a multimeter

If the scanner is not available or shows common errors, you should check the electrical circuits manually using a multimeter. The first thing to measure the voltage at the contacts of the power supply of the electric motor with the ignition on. The lack of voltage will indicate a problem in the power supply chain, possibly a relay burned or a wire broke.

Next, you should check the resistance of the engine windings and the integrity of the sensors. To do this, the motor connection chip is disconnected, and the corresponding pairs of contacts are called. The resistance of the windings must be within the norm specified in the manual for a particular model. Toyota, Volkswagen or Hyundai. A significant deviation or break indicates the need to replace the node.

It is also important to check the “mass” of the body and engine. Poor mass contact can cause a chaotic behavior of an electric booster when it is running and shutting down. Clear the contacts and make sure the mounting of the terminals is reliable.

Torque sensor verification and calibration

The central element of the system is a torque sensor, which tells the control unit with what force the driver turns the steering wheel. If this sensor is not working correctly, the amplifier may not turn on or, conversely, work with jerks. Before replacing an expensive node, try to perform a calibration (zero point) procedure.

The calibration procedure is usually performed through a diagnostic connector or a specific sequence of actions with the ignition key and steering wheel. The exact algorithm depends on the brand of the car and is prescribed in the service documentation. During calibration, the system remembers the position of the “straight wheels” and adjusts the sensor readings.

If the calibration does not help and the scanner shows discrepancies in the sensor readings when turning the steering wheel, it is likely that its replacement will be required. Sometimes the problem lies in the plume of the sensor, which can be rubbed inside the column.

Typical symptoms of an electric motor malfunction

Electric motor EPS This is an actuator that most often fails due to wear of brushes or collector. A characteristic sign of wear is the appearance of sparkling and a specific smell of burning from under the torpedo or from the engine compartment. There may also be a decrease in the maximum speed of rotation of the shaft.

Often drivers complain that the amplifier is turned off at high speeds or with prolonged steering in the extreme position. This can be a protective reaction of the system to overheating, but also a sign of degradation of the engine characteristics. In such cases, it is better to replace the engine, as repair may not be economically feasible.

⚠️ Attention: Operation of the car with faulty electric power steering is allowed only in emergency mode to the repair site. Driving without an amplifier requires much greater physical effort and increases the braking distance of the driver’s reaction.

Check the mechanical part of the gearbox as well. Wear of gears or lack of lubrication can create an additional one that the motor is unable to overcome, which will be perceived as an electrical malfunction.

The impact of on-board network voltage on EPS

The electric power system is very sensitive to voltage drops. If the battery is discharged or the generator does not produce sufficient current, the control unit can forcibly turn off the amplifier to save energy and ensure the operation of the engine. Therefore, checking the status of ACB The generator is a mandatory stage of diagnosis.

Subsidences of voltage are especially noticeable at the time of engine start-up or the inclusion of powerful consumers (headlights, stove). If the steering wheel becomes heavy at these times, the problem is most likely with the charging system. Check the tension of the generator belt and the state of the battery terminals.

Self-checking of work after repair

After repairs or replacement of nodes, you must ensure the correct operation of the system. Start the engine and pay attention to the indicator EPS on the dashboard. The light bulb should light up when the ignition is turned on and go out a few seconds after starting the engine.

Make a few full turns with the steering wheel left and right on the muted, and then on the started engine. The force must be minimal and uniform throughout the course. The absence of jerks, snacks and extraneous noises indicates a successful repair.

If all parameters are normal, the diagnosis can be considered complete. However, if the problem is recurrent, a more in-depth oscilloscope diagnosis may be required to analyze the shape of the sensors signal.