What does it mean?
OBD II fault code B2325 is a manufacturer specific code that is defined by Ford, Lincoln, Mazda, Mercury, and Nissan as “Mirror Driver Vertical Feedback Potentiometer Circuit Open” and on these applications, code B2325 is set when the PCM (Powertrain Control Module) or, Body Control Module, detects an open circuit in an electronically controlled side view mirrors’ feedback loop.
NOTE: In this definition, “Vertical feedback” refers to the circuit that controls the movement of the mirror around the vertical (side-to-side) axis, and “Potentiometer” refers to the device in the mirror that provides the controller with information on the mirrors’ position relative to a base setting.
In practical terms, the adjustment and control of side view mirrors is accomplished by small electric motors that can tilt a mirror either from side to side (vertical axis), or up and down, (horizontal axis), or both at the same time, depending on the application. On many, if not most, applications, the amount of movement is programmable, meaning that one or both mirrors can be programmed to move only within a range set by the programmer.
To enable programming, each drive motor is connected to a potentiometer, which is a type of variable resistor that passes a variable voltage, depending where in its rotation the moving part of the potentiometer (aka, the wiper) stops on a resistive winding or strip. Refer to the image below. If the wiper is stopped halfway along the resistive strip, the potentiometer will theoretically pass only 50% of the voltage that entered it.
Therefore, by moving the wiper to different positions on the resistive strip, the exiting voltage can be adjusted to serve as a sort of baseline reference voltage a controller can use to move a mirror between an upper and lower voltage limit. Thus, when a mirror is being programmed, the controller will remember both the upper and lower limits of the voltage generated by the potentiometer during the programming procedure.
However, during the mirror’s movement, the current that is allowed to pass through the potentiometer also serves as a form of feedback, and the controller will cut power to the actuator when either the previously programmed upper or lower voltage limit is reached. In practice, when this feedback voltage is interrupted or absent, the controller cannot control the mirror and code B2325 will be set, which depending on the application, may, or may not trigger a warning light.
The image below shows detail of the mechanics of an electronically adjustable/controlled side view mirror. Note the two drive motors and the potentiometer that is geared to each. Note that each motor controls adjustment of the mirror around one axis. Be aware that while the example shown here is somewhat typical, the actual arrangement and appearance of the various components in an adjustable mirror can differ greatly between applications.
Symptoms
- The driver mirror does not move side to side when a memory position is recalled.
- The mirror overtravels or stops early because the controller cannot see when to cut power to the actuator.
- Mirror position cannot be stored, so programming a new memory setting fails.
- Automatic tilt in reverse does not work on the driver mirror.
- Depending on the vehicle, a warning lamp or message may not appear at all, and the driver notices only the lost function.
Likely causes
- Broken conductor in the driver door harness where it passes through the rubber boot into the body, the most common failure point on this circuit.
- Mirror connector unlatched, or a terminal pushed back after mirror glass, door trim or speaker work.
- Corroded pins in the mirror connector after water entered the housing.
- Worn out resistive track so the wiper loses contact at some point in its rotation and the feedback voltage disappears.
- Missing reference voltage or sensor ground supplied by the controller.
- Internal break in the actuator wiring after the mirror glass was pushed by hand or by a car wash brush.
- Failed controller output that supplies the potentiometer reference.
How to fix it
- Read the codes and check whether both the driver mirror axes or only the vertical one are affected.
- Watch the vertical feedback value in live data while running the mirror slowly across its full side to side travel.
- A value that vanishes at a particular point separates a worn potentiometer track from a wire that is broken all the time.
- Measure reference voltage, signal and ground at the mirror connector; if the reference is missing, work back toward the controller.
- Check continuity of the feedback wire end to end while flexing the harness in the door boot, where conductors typically break.
- Repair the broken wires with sealed crimped joints rather than tape splices, and replace corroded terminals.
- Replace the mirror actuator assembly only when the harness and reference are proven good, then relearn the mirror memory positions.