Memory 2 Switch Circuit Short To Ground
The vehicle's seat belt pretensioner or memory seat switch is electrically shorted to ground, like a wire touching metal when it shouldn't. The ECU detected abnormally low voltage instead of the expected signal from this switch circuit.
The ECU monitors the Memory 2 Switch circuit voltage, expecting a high signal when the switch is open and low when closed. When a short to ground occurs, the voltage drops to 0V continuously, indicating a wiring fault or internal switch failure. The ECU cannot distinguish normal switch operation from a direct short.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Circuit Voltage | Above 2.5V (open), below 1V (closed) | Sustained 0V or below 0.5V when expecting high signal |
| Resistance to Ground | Above 10 kΩ when open | Below 100 Ω indicating short path to ground |
Code B1538 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B1538 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.