If your vehicle’s diagnostic system has triggered code B1380, it means the onboard computer has detected a malfunction in the rear wiper motor circuit. This body code affects the electrical system controlling your rear windshield wiper and can prevent it from operating properly. While not a critical safety issue in most cases, a non-functioning rear wiper can reduce visibility and should be diagnosed and repaired promptly.
What Does Code B1380 Mean?
Code B1380 is a body diagnostic trouble code that specifically targets the rear wiper motor circuit. The “B” prefix indicates this is a body system code (as opposed to powertrain or chassis codes). When this code is set, the vehicle’s control module has detected an electrical fault in the circuit responsible for operating the rear windshield wiper motor.
The rear wiper motor circuit includes several components: the wiper motor itself, the control switch, the relay, wiring harnesses, connectors, and the body control module (BCM) that manages the system. A malfunction code means the BCM has detected abnormal voltage, resistance, or signal patterns that indicate a problem somewhere in this circuit.
Common Symptoms
- Rear wiper won’t operate: The most obvious symptom—the rear wiper blade doesn’t move when activated
- Intermittent rear wiper operation: The wiper works occasionally or inconsistently
- Rear wiper stuck in one position: The blade remains in the parked or mid-sweep position
- Slow rear wiper movement: The wiper operates but moves slower than normal
- Check Engine Light or warning message: Dashboard illuminates with the diagnostic trouble code
- Rear wiper runs continuously: The wiper won’t stop once activated
- Burning smell near rear hatch: Indicates electrical short or motor overheating
- No response to wiper controls: The switch doesn’t activate the rear wiper at all
Possible Causes
Listed from most to least common:
- Faulty rear wiper motor (Most Common): The motor itself has failed electrically or mechanically, preventing proper operation or causing excessive current draw
- Corroded or loose electrical connectors: Oxidation or poor connections at the motor connector, relay, or switch reduce electrical flow
- Damaged wiring harness: Broken, frayed, or pinched wires in the rear wiper circuit create open or short circuits
- Faulty wiper relay: The relay that controls power to the motor has failed and won’t switch properly
- Defective wiper control switch: The dashboard switch used to activate the rear wiper is malfunctioning
- Body Control Module (BCM) fault: The computer controlling the wiper circuit has developed an internal fault
- Blown fuse: The dedicated fuse for the rear wiper circuit has opened
- Water intrusion: Moisture has entered the motor housing or electrical connectors, causing corrosion or short circuits
- Mechanical jam: The wiper blade or linkage is stuck, causing the motor to stall and trigger a current overload fault
Diagnostic Steps
Step 1: Verify the Code and Symptoms
Use an OBD-II scanner to confirm code B1380 is present. Note whether the rear wiper is completely non-functional, intermittent, or operating abnormally. Check if any other codes are also set, as multiple codes can indicate a broader electrical issue.
Step 2: Inspect the Rear Wiper Motor and Connectors
Locate the rear wiper motor (typically mounted inside or near the rear hatch). Visually inspect the motor connector for corrosion, moisture, or loose pins. Gently wiggle the connector while an assistant activates the rear wiper to see if operation improves (indicating a loose connection). Look for any obvious water damage or green oxidation on the connector terminals.
Step 3: Check the Wiper Blade and Linkage
Manually move the rear wiper blade to ensure it’s not mechanically stuck or jammed. A stuck blade can cause the motor to stall and draw excessive current, triggering the fault code. Ensure the blade moves freely without resistance.
Step 4: Test the Wiper Control Switch
Activate the rear wiper control from the dashboard. Listen for a clicking sound from the relay (usually located in the fuse box). If you hear the relay click but the wiper doesn’t move, the motor is likely faulty. If you hear nothing, the switch or relay may be the problem.
Step 5: Check the Fuse
Locate the rear wiper fuse in the vehicle’s fuse box (consult your owner’s manual for the location and amperage). Remove the fuse and inspect it for a broken filament. If the fuse is blown, replace it with one of the correct amperage. If it blows again immediately, there’s likely a short circuit in the wiring.
Step 6: Perform Voltage Testing
Using a multimeter, test for voltage at the rear wiper motor connector when the wiper switch is activated. You should see battery voltage (typically 12V) at the motor. If no voltage is present, the problem is in the switch, relay, or wiring. If voltage is present but the motor doesn’t operate, the motor itself is faulty.
Step 7: Inspect Wiring Harness
Trace the wiring from the motor to the fuse box and control switch. Look for any visible damage, pinched wires, or areas where the harness may have rubbed through insulation. Pay special attention to areas near the hatch hinge where movement can damage wires over time.
Step 8: Test the Relay
If equipped with a separate relay, remove it from the fuse box and test it with a multimeter or swap it with an identical relay from another circuit (if available) to see if the wiper operates. A faulty relay will prevent power from reaching the motor.
Repair Cost Estimates
DIY Repair Costs:
- Rear wiper motor replacement: $30–$150 (part only)
- Wiper relay: $10–$30
- Electrical connectors/terminals: $5–$20
- Fuse: $1–$5
Professional Repair Costs:
- Rear wiper motor replacement: $150–$400 (including labor)
- Wiper relay replacement: $75–$200
- Wiring repair/harness replacement: $200–$600
- Control switch replacement: $100–$300
- BCM reprogramming/replacement: $400–$1,200
- Full diagnostic service: $75–$150
Costs vary significantly based on vehicle make, model, and year. Luxury or imported vehicles typically cost more for parts and labor.
Can I Still Drive?
Safety Assessment: Low to Moderate Severity
A non-functioning rear wiper is generally not a critical safety issue that prevents you from driving. However, visibility through the rear window is important for safe operation, especially in wet weather, rain, or snow. Driving without a functional rear wiper in poor visibility conditions increases the risk of accidents.
Recommendations:
- Short trips in clear weather: Safe to drive temporarily if visibility is good
- Avoid heavy rain or snow: Do not drive in wet conditions without a working rear wiper
- Schedule repair soon: Repair within a few days to avoid being caught in poor weather
- Check local regulations: Some jurisdictions require functional rear wipers; driving without one may result in a citation
Frequently Asked Questions
Q: Can a bad rear wiper motor cause other codes?
A: Yes. A severely faulty motor that draws excessive current can trigger additional electrical codes or even affect the body control module. If the motor is shorted, it may also blow the dedicated fuse repeatedly, potentially affecting other circuits sharing that fuse.
Q: Is code B1380 the same on all vehicles?
A: Code B1380 is standardized across most manufacturers for rear wiper motor circuit malfunctions. However, the specific components, wiring configuration, and diagnostic procedures may vary between vehicle makes and models. Always consult your vehicle’s service manual for model-specific information.
Q: Can I clear this code myself without fixing the problem?
A: You can clear the code with a scanner, but it will return within a few drive cycles if the underlying problem isn’t repaired. Clearing the code without fixing the issue is not recommended, as it masks a real electrical problem that could worsen or cause other issues.
Q: How do I know if it’s the motor or the wiring?
A: Voltage testing is the key diagnostic step. If voltage reaches the motor connector when the wiper switch is activated, but the motor doesn’t operate, the motor is faulty. If no voltage is present at the connector, the problem is in the wiring, switch, relay, or fuse. A professional technician with a multimeter can determine this quickly.