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GM electric power steering

How does GM electric power steering work?

GM’s Electric Power Steering System offers many advantages over the traditional hydraulic power steering systems. Here’s a list of the advantages:

• Better fuel economy because the engine doesn’t have to drive a power steering pump the entire time the engine is running.

• Less engine noise and vibration transmitted to the passenger compartment due to the lack of a power steering pump and belt.

• Removing the power steering pump and drive belt leaves more room under the hood

• Better safety. No more power steering fluid leaks

How does GM’s Electric Power Steering System Work?

The steering wheel is connected to a torsion bar. The

electric power steeering

Electric power steering upper portion

torsion bar is then connected to a shaft with a gear on it. This gear connects to the steering rack. The shaft is assisted with an electric motor. A sensitive torque sensor measures the amount of torque applied to the torsion bar. The sensor also senses which direction the steering wheel is turned.

The torque and direction information is fed into a power steering control module.  The module then applies power and ground to the electric motor that drives the gear on the lower shaft. The electric motor helps the shaft to rotate

The module also monitors vehicle speed so it can give more assist at low speeds for maneuverability and less assist at freeway speeds, for improved road feel and control. The module can send a request for the warning light if it detects a problem with a sensor input or motor circuit.

The power steering control module is programmed to the car’s options such as tire size, engine size, and suspension. This allows for the proper ‘steering feel’ for each application.

Power steering electric steering motor

The power steering motor is a heavy duty component that can draw up to 65 amps. It switches direction by reversing polarity. GM uses different types of power steering assist motors: 12-volt motors with 3-phase motors and 42-volt motors for hybrids.

electric power steering

Electric power steering gear/rack/motor

Steering sensors

Some designs use steering wheel position and torque sensors, while others use torque sensors with motor rotational sensors. However, they all work the same.

electric power steering

Steering angle/torque sensor

Fail safe mechanical connection to the steering gear

GM’s Electric Power Steering System Work is not totally fly-by-wire. In case of a failure, a mechanical connection from the steering wheel to the steering rack allows manual steering, just like conventional power steering. GM’s

If the power steering message appears, start your diagnostics by reading the trouble code.

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Posted on by Rick Muscoplat


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