A steering position sensor (also called a steering angle sensor) may not be the most exciting part of a car, but along with brakes and the suspension system, it’s an important part as far as safety goes. It’s a donut-shaped sensor located in the steering column under the dash in GM vehicle.
The Purpose of the Steering Position Sensor
The steering position sensor is an important part of the StabiliTrack Electronic Stability Assist system, which is a sophisticated GM-designed system to improve vehicle stability and steering feel. The system includes a 'steering wheel position sensor,' which has one important function:
- The steering position sensor monitors the angle of the steering input in degrees, and reports that information to the ECU (the main computer in the vehicle)
- The ECU then activates or deactivates something called the Electronic Variable Orifice (EVO), which basically controls the flow of fluid in the power steering system, effecting the amount of 'boost' you get from the steering system.
The intent of this entire system is to provide more boosted steering at slow speeds, and less boost at higher speeds.
The sensor plays a big part in ensuring predictable steering, and if it wears out that can lead to some serious problems, potentially even loss of control over steering.
Symptoms of a Failing Steering Position Sensor
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Because of the safety concerns around a failing steering position sensor, it's a good idea to catch this problem early. You can detect a failing steering position sensor by watching for these common symptoms:
- Steering that changes from over-boosted to under-boosted during the same turn.
- Steering that is over-boosted all the time.
- The traction control light coming on.
Testing for Steering Position Sensor Failure
If you suspect a problem with your vehicle's steering position sensor, there's a simple 5-minute test you can do to diagnose it. All you need is an ohmmeter. Here's how you go about it:
- Go underneath the dash and locate the steering column.
- Next to the column is a wiring connector wrapped in foam tape. Grab a nonmetallic tool and scrape off enough foam tape so that you can access the connector.
- Use a small flathead screwdriver or pick to remove a plastic retaining pin from the connector. Then unplug the connector.
- Connect an ohmmeter to the orange and blue leads of the sensor. (NOTE: Wire color may be different on your vehicle, so be sure to check your shop manual or 'google' it. Just know that no harm will be done if you measure the wrong leads.)
- Have a friend turn the wheel back and forth. Watch the ohmmeter and if the value exceeds 12,000 ohms, or shows an open circuit, then it’s time to replace the sensor. If the value stays under 12,000 ohms, then the sensor likely still works well.
NOTE: These steps may vary slightly depending on your GM year model.
How to Fix a Failing Steering Position Sensor
If your ohmmeter reads over 12,000 ohms, you might be wondering how to fix this issue. One option is to simply replace the steering position sensor (part no. 26064468). It is a simple process that involves only one bolt and a new sensor.
Another Option - Bypass the EVO
Both the steering position sensor and the EVO solenoid valve in certain GM power steering systems are prone to failure. GM addressed the issue by introducing a kit designed to replace the EVO solenoid valve with a bypass pipe. When installed, the bypass pipe simply bypasses the EVO solenoid valve. This means a steering position sensor will no longer be necessary, and you don't need to replace it.
Bypassing the EVO might be a good solution for your vehicle if you're having chronic issues with the steering wheel position sensor or EVO in your vehicle. However, there are a couple of things to know about bypassing the EVO:
- The boost in the steering system will now be constant at all speeds. As compared to prior system, the driver will feel slightly firmer steering at low speeds and slightly lighter steering at high speeds.
- The engine computer may register a 'check engine' light from time to time as a result of this bypass. Nothing will be broken, but the computer may be confused and register a false alarm. This can be annoying, since you really don't want to check your ECU for codes every time you see that light.
Still, a bypass kit is basically a permanent fix for EVO and/or steering wheel position sensor problems.
GM offers an official bypass kit (part no. 19168825), and like all OEM GM parts you can rest assured it will fit properly and work as intended.