Driver Power Window One Touch Window Relay Circuit Failure
The car's electrical relay that controls the driver's one-touch power window feature isn't working properly. Think of it like a light switch that's stuck or broken—the signal gets sent but the window won't respond.
The Body Control Module (BCM) monitors the relay circuit voltage and current draw when the one-touch command is activated. It detects opens, shorts, or excessive resistance in the relay coil or switch circuit by checking if expected voltage levels and current flow are present.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Relay coil voltage | 12V supply when activated | Below 10V or no voltage detected |
| Relay contact resistance | Less than 0.5 ohms when closed | Greater than 2 ohms or open circuit |
Code B1398 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, B1398 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.