All drivers that own and operate cars, trucks, and SUVs in the United States are taught at an early age to use side windows and move their heads to ensure they have clearance to change lanes. Before starting their vehicles, they are also taught to fasten their seatbelts and make sure their side and center mirrors are properly adjusted to allow them safe operation of the vehicle. On most vehicles, the adjustment of side mirrors is completed thanks to an electronic mirror control switch.
The mirror control switch is typically located on the driver's side door or on the left-hand side of the dashboard. It's comprised of a series of selector and adjustment switches. The selector switch permits the driver to choose the driver or passenger side mirror that needs to be adjusted. Once they choose an option, the driver utilizes either a knob or directional switch to adjust the mirror up, down, or side-to-side for the perfect alignment. There is also a control switch on the passenger side, which is commonly referred to as the slave switch.
Mirror control switches control both power and an electrical ground to each of the mirror motors that allow them to move. Under normal conditions, when the driver selects one of the mirrors and pushes the mirror switch up, a set of electrical contacts inside the switch connect power and ground to the up/down mirror motor to move that mirror up. In the down position, the mirror switch reverses the electrical polarity to the motor and the mirror goes down. The same action occurs directionally when the driver chooses to move the mirror to the left or right.
When the switch fails or is showing signs of failure, it will display a few warning signs or symptoms that should alert the driver that the mirror control switch needs to be fixed or replaced by a certified mechanic. Noted below are a few of the warning signs that a faulty mirror control switch exists inside a vehicle.
1. Mirrors adjust up and down but not left to right
In some cases the mirrors will adjust from top to bottom, but when the driver tries to adjust them sideways, the mirror does not move. This is commonly caused by either an electrical malfunction inside the switch or an issue between the switch and the electrical relay that sends a signal to the motor that operates the mirror. If you recognize this symptom, it's a good idea to contact a local ASE-certified mechanic who can inspect the switch for damage. In most cases, the mechanic will replace the switch as it's commonly the component that is causing this symptom.
2. Mirrors adjust side to side but not up and down
These two symptoms of inconsistent operation of the electric mirror are similar in nature but can have different root causes. The mirror switch has several sets of electrical contacts inside them where corrosion can build up, causing a faulty circuit inside the switch. In many situations, these symptoms are the result of wire or connection issues external to the switch. A thorough inspection of broken mirror switches of the mirror system is necessary to find out why your mirrors are not working as designed.
3. Mirrors do not adjust at all
Believe it or not most of the time this symptom is caused by a human error. The mirror control switch has a neutral setting that disables the switch in case it is bumped by the drivers arm on accident. Many vehicle owners simply forget to check the switch to see if it's set in this position. If the mirror control switch is not in the neutral or lockout position and your mirrors do not adjust at all, then the switch could have an open circuit internal to the switch. This means that no power can flow through the switch to the mirror motors. Switches are not repairable items; they are replaced by ASE certified mechanics only.
4. Mirrors adjust from the master (driver) switch but not the slave (passenger) switch
There are several possible causes of this symptom. The mirror lockout switch could be in the neutral position, the slave switch could be faulty, there could be no power to the slave switch, or the circuits between the two switches could have a problem.
If you recognize any of the above warning signs, make sure to contact one of our local ASE certified mechanics so they can arrive to your home or office and complete a detailed diagnostic check to determine if the mirror control switch needs to be replaced and complete the service quickly and affordably.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Mirror Control Switch and was authored by Timothy Charlet.