The passenger side mirror's vertical adjustment switch is sending a constant "battery power" signal to the ECU instead of the expected variable signal, like a stuck light switch that won't turn off. This electrical short prevents the mirror from responding to adjustment commands.
The ECU monitors the voltage signal from the passenger mirror vertical switch circuit, which should vary between ground and battery voltage as the switch is activated. When shorted to battery, the voltage remains constantly high instead of toggling, preventing the ECU from detecting legitimate switch commands.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Switch voltage signal | 0V to 12V (variable with switch actuation) | Constantly at battery voltage (12V+) |
| Circuit resistance | Variable (100-10k ohms depending on position) | Near 0 ohms (short condition) |