The electronic power steering control unit was designed to help solve a constant problem that occurred with most traditional power steering systems. Under the normal, belt-driven hydraulic power steering set up, a belt was attached to a series of pulleys (one at the crankshaft and one on the power steering pump). The constant operation of this belt-driven system put a tremendous load on the engine, which resulted in loss of engine horsepower, fuel efficiency and increased vehicle emissions. Since vehicle engine efficiency and reducing emissions became the primary mission for most automotive manufacturers before the turn of the century, they solved a lot of these issues by inventing an electrically assisted power steering motor. This system removed the need for power steering fluid, power steering pumps, belts, and other components that operated this system.
In some instances, if a problem exists with this system, your electronic power steering system will automatically shut down to prevent damage from overheating. This is primarily seen when driving on steep slopes with lots of turns. In these instances, there is nothing wrong with the system and normal operation will resume once the temperature has reduced. However, if there is a problem with the power steering control unit, it may display a few common warning signs that will alert the driver that it may be necessary to replace this component. Some of these symptoms include the EPS indicator light is illuminating on the dashboard, or trouble steering the vehicle.
Part 1 of 1: Replacing the power steering control unit
- Boxed end wrench or ratchet wrench
- Penetrating oil (WD-40 or PB Blaster)
- Regular sized flat blade screwdriver
- Replacement power steering control unit
- Safety equipment (safety glasses & gloves)
- Scan tool
- Specialty tools (if required by manufacturer)
Step 1: Disconnect the vehicle's battery. Before removing any parts, locate the vehicle's battery and disconnect the positive and negative battery cables.
This step should always be the first thing you do when you work on any vehicle.
Step 2: Remove the steering column from the steering box. Before you remove the interior dashboard or covers, make sure you can remove the steering column from the steering box first.
This is often the most difficult part of the job, and you should first verify that you have the right tools and experience to complete it before you remove the other components.
To remove the steering column, you'll have to complete the following steps on most domestic and import vehicles:
Remove the engine covers and other components that block access to the steering box. This could include the engine cover, air filter housing, and other parts. Remove any electrical connections to the steering column and steering box.
Locate the steering box and steering column connection. Typically it's connected by a series of bolts (two or more) that have a bolt and nut ending securing them. Remove the bolts securing the two components together.
Place the steering column shaft aside and proceed to the driver's compartment to remove the dashboard and steering wheel.
Step 3: Remove the steering column covers. Each vehicle will have different instructions for removing the steering column covers. Typically there are two bolts on the sides and two on the top or bottom of the steering column that are hidden by plastic covers.
To remove the steering column cover, remove the plastic clips covering the bolts. Then remove the bolts that secure the housing to the steering column. Finally, remove the steering column covers and place them aside.
Step 4: Remove the steering wheel. Most vehicles will require you to remove the air bag center section from the steering wheel before you are able to remove the steering wheel.
Refer to your service manual for these exact steps.
After you've removed the air bag, you can usually remove the steering wheel from the steering column. On most vehicles, the steering wheel is attached to the column by one or five bolts.
Step 5: Remove the dashboard. All vehicles have different steps and requirements for removing the dashboard, so refer to the service manual for exact steps to follow.
Most power steering control units are only accessible when the lower dashboard covers are removed.
Step 6: Remove the bolts attaching the steering column to the vehicle. On most domestic and imports, the steering column is attached to a housing that is secured to the firewall or the vehicle's body.
Step 7: Remove the electrical harness from the power steering control unit. There are usually two electrical harnesses that are attached to the steering control unit.
Remove these harnesses and mark their locations with a piece of tape and a pen or a colored marker.
Step 8: Remove the steering column from the vehicle. Once you've removed the steering column, you'll be able to replace the power steering control unit on a work bench or other area away from the vehicle.
Step 9: Replace the power steering control unit. Using the instructions provided to you by the manufacturer in the service manual, remove the old power steering control unit from the steering column and install the new system.
Usually they are secured to the steering column with two bolts and can only be installed one way.
Step 10: Reinstall the steering column. After the new power steering control unit has been installed successfully, the rest of the project is simply putting things back together in the reverse order of removal.
Install the steering column from the driver's compartment. Secure the steering column to the firewall or housing. Attach the electrical harnesses to the power steering control unit. Reinstall the dashboard and steering wheel.
Reinstall the air bag and reattach the electrical connections to the steering wheel. Reinstall the steering column covers and reattach them to the steering box.
Reattach all the electrical connections to the steering box and steering column inside the engine compartment. Reinstall any engine covers or components you had to remove in order to gain access to the steering box.
Step 12: Test start and drive the car. Reconnect the battery and clear all error codes in the ECU with a scan tool; they need to be reset in order for the system to relay information to the ECM and work correctly.
Start the vehicle and turn the steering wheel to the left and right to verify that the steering works correctly.
Once you've completed this simple test, take the vehicle on a 10 to 15 minute road test to ensure the steering system works correctly on different road conditions.
If you've read these instructions and still don't feel 100% confident in completing this repair, please contact one of the local ASE certified mechanics from YourMechanic to complete the power steering control unit replacement for you.
This article originally appeared on YourMechanic.com as How to Replace a Power Steering Control Unit and was authored by Timothy Charlet.