Transitioning into electronic power steering service can come with several challenges for your business and service team. Perhaps the biggest change you'll need to undergo is the radical shift in the diagnosis and repair processes today's EPS systems demand. You and your team will need to learn to address and entirely new field of electronic failures that require a different approach than you would use to repair the mechanical, hydraulic issues you might be used to.
Thankfully, you can begin to study these failure modes now in order to prepare your service team to diagnose and repair them. In this post, we'll discuss the most common EPS electronic column system failures and touch on how your process will need to change in order to address them.
Main Types of EPS Electronic Failure Modes
There are three main types of electronic system failures that you're likely to see when inspecting and repairing today's EPS systems: motor, electronic board, and torque sensor issues. Here's a quick rundown of the types of failures associated with each of these service categories. These failure modes are related to the electronic column drive system with a mounted electric motor and manual rack and pinion.
Today's electronic power steering systems may fail due to issues with the mounted electric motor. In particular, excessive heat on the motor is likely to cause the failure modes. Infiltration of the system environment by water, dirt, or other contaminants will also likely lead to EPS failure. Additionally, in brush style systems only, carbon contamination may lead to steering failure. In general, brush style is more prone to failure than brushless.
Electronic Board and Circuitry
Another area of concern is the electronic board and circuitry. The EPS board processes the electrical signals passing through the system and is a hub of communication between sensors and circuits in the system. In particular, failure modes to be on the lookout for include heat and power cycling over time (mosfets, relays, capacitors, resistors). These are more of an issue when located near the engine and exhaust components. Infiltration of the system by water, dirt, or other contaminants can also cause EPS failures. However, the microprocessors typically do not fail and shouldn't be a main concern during diagnosis and repair.
Finally, another common failure type is related to the torque sensor. A torque sensor failure is actually the most common failure on column assist, and a contacting style torque sensor has a much higher failure rate than non-contacting sensors. On contacting sensors, the metallic contact points tend to wear over time.
Diagnosing and Servicing Electronic Steering Failures
EPS service is fundamentally different than hydraulic steering service due to the nature of its electronic design. Instead of repairing and replacing mechanical components, EPS service deals with electronic calibration and programming in addition to some component work. Due to this design, electronic failures cannot always being diagnosed upon a physical inspection of the system the way that older hydraulic steering issues could. In order to service these types of EPS failure modes on late model vehicles, your shop will need to implement a new service process for dealing with electronics, including: