Window Relay Circuit Failure
Window power relay circuit is malfunctioning.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The window relay that controls the power to your windows isn't working right, possibly due to a bad relay or a wiring issue.
What the computer is actually seeing
The body control module (BCM) expects to see a specific voltage signal when the window switch is activated. If it doesn't see the expected voltage or sees a short circuit, it triggers the B1644 code.
What a healthy reading looks like
When the window switch is pressed, the BCM should see 12V on the control signal for the window relay. If there's a fault, the voltage may drop to 0V or fluctuate inconsistent with expected behavior.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors from the BCM to the window relay for damage or corrosion. - Is there visible damage?
- 22. Check the window relay for proper operation by testing it with a multimeter using the relay test function. - Is the relay functioning?
- 33. Measure the voltage at the window switch while pressing it. You should see 12V. - Are you getting the correct voltage?
- 44. If not, trace the wiring back to the BCM and check for shorts or breaks. - Are there any shorts or breaks in the wires?
- 55. If all above checks out, replace the window switch and retest the system.
Common causes
- Faulty window relay
- Wiring issues or shorts
- Dirty or corroded connector pins
- Faulty window switch
- Dead battery or poor ground connection
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, driving is safe but you won't have functional windows until repaired.
Will this problem come back after fixing?
If the underlying cause is not addressed, like a wiring short, it may return.
Why do I see this with a door lock issue?
Both systems may share similar circuitry, affecting each other.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →