B2249 – Right rear window motor circuit open (BYD)

B2249 means the right rear window may not move at all, or it may work only sometimes. You will usually notice the window switch does nothing and the window stays stuck. This is a manufacturer-specific BYD body code, and it can vary by platform. According to BYD factory diagnostic data, this code indicates an open circuit in the right rear window motor circuit. In plain terms, the control module tried to run the window motor but “lost” the electrical path. The code points you to a circuit problem first. It does not confirm a bad motor until you prove the wiring and control outputs.

B2249 Quick Answer

B2249 on a BYD typically means the right rear window motor circuit has an open. The right rear power window will often be inoperative until you restore the circuit path.

What Does B2249 Mean?

Official definition: “Right rear window motor circuit open.” In practice, the BYD body system cannot drive or confirm current flow through the right rear window motor circuit, so the window may stop responding or become intermittent.

What the module detects and why it matters: The body control system monitors the motor drive circuit when it commands the window up or down. It expects to see a valid electrical load and a plausible circuit response. When the circuit goes open, the module sees no effective load or an implausible feedback condition and stores B2249. That matters because the root cause can be anywhere in the motor feed, motor ground, door-jamb harness, connector pins, or the module’s output stage. You must confirm the open with circuit testing before replacing parts.

Theory of Operation

On BYD vehicles, the body electrical system controls the power windows through a switch network and a control module output stage. When you press the right rear switch, the module commands the window motor in one direction. It does that by applying power and ground across the motor using reversible polarity control.

B2249 sets when that commanded motor circuit cannot carry current. A broken wire, loose connector, or damaged terminal can open the circuit. A seized regulator can also trigger an “open-like” condition if a protection strategy shuts down the output. Your job is to prove whether the open sits in the wiring, the motor, or the control output.

Symptoms

These symptoms match an open circuit in the right rear window motor circuit.

• Inoperative window: Right rear window does not move up or down.
• Intermittent operation: Window works only when the door is moved or slammed.
• No motor sound: You hear no motor noise when you press the switch.
• Switch abnormality: Right rear switch feels normal but produces no response.
• Driver control issue: Master switch cannot control the right rear window.
• Auto function loss: One-touch or anti-pinch behavior may disable for that window.
• Stored body DTC: Scan tool shows B2249 in the body system history or current list.

Common Causes

• Open in the motor power feed: A break in the feed wire prevents current from reaching the right rear window motor, so the control module sees an open circuit during command.
• Open in the motor ground path: A damaged ground wire or loose ground point stops motor current flow, which makes the circuit look “open” even if the motor itself is good.
• High-resistance connector at the right rear door: Corrosion, spread terminals, or poor pin fit at the door harness connector reduces current enough that the module flags an open-type fault.
• Broken wires in the door jamb flex boot: Repeated door movement commonly fractures conductors inside the rubber boot, which creates an intermittent or hard open to the motor circuit.
• Faulty right rear window motor internal open: An open armature, thermal protector, or internal brush failure stops current flow and mimics a harness open when the module commands movement.
• Window regulator binding or stalled motor load leading to protective shutdown: A jammed regulator can force the driver circuit to shut down, and the module may log an open-type failure when it cannot drive the circuit.
• Switch module or master switch signal fault: A failed switch contact or internal switch electronics can block the command path, so the motor never receives drive and the module interprets the motor circuit as open.
• Output driver fault in the body/window control module: A failed internal driver transistor or relay path can prevent power or ground from being applied to the motor circuit during actuation.

Diagnosis Steps

Use a scan tool that can access BYD body functions, command the right rear window, and display window-related inputs. You also need a DVOM, a fused test light, and back-probing tools. Plan on voltage-drop testing with the motor commanded. A wiring diagram for the Atto 3 platform helps identify the motor feed and return paths.

1. Confirm DTC B2249 in the body system and record freeze frame data. Focus on battery voltage, ignition state, and any window command status at the time the DTC set. Save the report, then check for related window or door module codes that may steer the path.
2. Inspect the obvious circuit path before meter work. Check the right rear window operation from both the rear switch and the driver master switch. Then inspect the right rear door jamb boot, door harness routing, and any signs of prior door repair or pinched wiring.
3. Check fuses and power distribution for the power window system. Verify the correct fuses feed the window system and that they seat tightly. Confirm fuse power on both sides with ignition in the same state shown in freeze frame.
4. Verify the controlling module power and ground under load. Perform voltage-drop testing on the module ground while commanding a window function. Keep ground drop under 0.1V with the circuit operating, because a weak ground can create false open-circuit conclusions.
5. Use the scan tool to run an output test or active command for the right rear window motor. Watch for any parameter that shows command direction, switch request, or motor drive status. Note the difference between freeze frame (when the DTC set) and a scan-tool snapshot you trigger during repeated commands to catch an intermittent open.
6. At the right rear window motor connector, check for drive voltage while commanding UP and DOWN. Do not rely on continuity alone. The module typically reverses polarity to change direction, so you should see the drive swap between the two motor pins when you reverse the command.
7. Load-test the motor feed and ground circuits. Use a fused test light or a suitable load tool between the suspected feed and ground while commanding the motor. A circuit can show battery voltage with no load and still fail under load due to corrosion or a fractured conductor.
8. Perform pinpoint voltage-drop tests across each suspect connection during a commanded window move. Measure across the door connector terminals, across splice points, and across any ground fastener. A big drop across one connection identifies high resistance that can set an open-type DTC on BYD systems.
9. If voltage and ground look correct at the motor connector during command, test the motor and regulator mechanically. Disconnect the motor from the regulator if service information allows, and verify the regulator moves freely. A binding regulator can stall the motor and change module behavior.
10. If the motor does not run and the circuit tests good, confirm motor integrity. Check motor resistance for an obvious open and then bench-test the motor with a fused power source if you can do it safely. If the motor runs on the bench but not in the vehicle, return to connector pin fit and driver output testing.
11. After repairs, clear DTCs and rerun the same output test that originally failed. Cycle ignition and recheck for immediate reset, because hard open faults monitored by the CCM often return at key-on. Confirm normal operation from both switches and verify no pending or stored body DTCs return.

Professional tip: If B2249 switches between pending and stored, treat it as an intermittent open. Flex the door harness at the jamb while commanding the motor and recording a scan-tool snapshot. A fractured conductor often fails only in one door position, and a static continuity check can miss it.

Possible Fixes

• Repair the open or high-resistance section of the right rear window motor power or ground circuit, then confirm with a loaded voltage-drop test.
• Clean, tighten, or replace terminals at the right rear door connector or motor connector after verifying poor pin fit or corrosion.
• Repair broken wiring inside the door jamb boot and add proper strain relief to prevent repeat conductor fatigue.
• Correct a binding window regulator or guide issue that stalls the motor and disrupts normal driver operation.
• Replace the right rear window motor only after the circuit proves capable of carrying load and the motor fails bench testing.
• Replace or repair the responsible BYD body/window control module output stage only after you verify power, ground, commands, and wiring integrity.

Can I Still Drive With B2249?

Yes, you can still drive your BYD with DTC B2249 in most cases. This code targets the right rear window motor circuit, not the high-voltage drive system. Expect the right rear window to stop working, work intermittently, or reverse unexpectedly. Do not keep cycling the switch if the window stalls. That habit can overheat the motor or stress the door wiring. Keep that window closed in bad weather and when parked. If the window sits partially open, address the fault soon. Water entry into the door can create additional electrical issues.

How Serious Is This Code?

B2249 usually rates as low severity for drivability. It does not change steering, braking, or propulsion on a BYD Atto 3. Treat it as more serious when the window will not close, the glass drops by itself, or you hear repeated clicking in the door. Those signs point to an active electrical problem. An “open circuit” fault often comes from a broken wire in the door jamb or a loose connector. Either condition can worsen with door use. A persistent open can also trigger body control logic to disable the window for protection until the next key cycle.

Common Misdiagnoses

Technicians often replace the right rear window motor first. That wastes money when the circuit opens in the door harness or connector. Another common miss involves testing with no load. A corroded terminal can pass a meter check, yet fail under motor current. Some shops also blame the window switch without proving the module can drive the motor outputs. Avoid these mistakes by commanding the window with a scan tool, if supported, and by doing voltage-drop tests while the motor should run. Always inspect the door jamb boot area closely. BYD door harness flex points fail more often than the motor itself.

Most Likely Fix

The most frequent confirmed repair direction for BYD B2249 involves restoring continuity in the right rear window motor feed/return circuit. Focus on the right rear door harness at the hinge area and the motor connector inside the door. Repair a broken conductor, reseat a backed-out terminal, or correct corrosion and poor pin tension. After repairs, verify the fix by operating the window repeatedly with the door open and closed. Confirm the DTC does not reset. The exact enable criteria for this body DTC can vary by BYD platform, so use service information to confirm the final verification routine.

Repair Costs

Repair cost depends on whether the confirmed root cause is a sensor, wiring, connector issue, or control module problem. Verify the fault electrically before replacing parts.

Last updated: March 30, 2026