B1818 – Wiper Rear Motor Up Relay Coil Circuit Failure

The ODBII code B1818 indicates a failure in the rear wiper motor up relay coil circuit, which may involve issues such as an open circuit, short circuit, or a malfunctioning relay affecting the operation of the rear wiper.

The severity of ODBII code B1818 is generally considered moderate.

Common Causes For: B1817 Wiper Rear Motor Down Relay Coil Circuit Short To Ground

• Faulty rear wiper motor
• Damaged wiring or connectors
• Failed relay
• Short circuit in the circuit
• Open circuit in the circuit
• Corroded terminals
• Faulty switch or control module
• Grounding issues

Common misdiagnosis for B1818 Wiper Rear Motor Up Relay Coil Circuit Failure

• Faulty rear wiper motor
• Bad wiper switch
• Wiring issues or shorts in the circuit
• Defective relay
• Poor ground connection
• Malfunctioning body control module (BCM)
• Incorrectly diagnosed front wiper issues

Common Troubleshooting Steps

The OBD-II code B1818 indicates a problem with the rear wiper motor up relay coil circuit. This code typically points to an issue with the electrical components related to the rear wiper system. Here are some common troubleshooting steps to diagnose and potentially resolve the issue:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information regarding the rear wiper system and wiring diagrams.
• Visual Inspection:
• Inspect the wiring and connectors associated with the rear wiper motor and relay for any signs of damage, corrosion, or loose connections.
• Check the condition of the rear wiper motor itself.
• Test the Relay:
• Locate the rear wiper relay in the fuse box or relay panel.
• Swap the relay with a similar one (if available) to see if the problem persists.
• Use a multimeter to test the relay for continuity and proper operation.
• Check Fuses:
• Inspect the fuses related to the rear wiper system. Replace any blown fuses and check if the issue is resolved.
• Test the Wiper Motor:
• Disconnect the rear wiper motor and test it directly by applying power to see if it operates.
• If the motor does not work when powered directly, it may need to be replaced.
• Check for Ground Issues:
• Ensure that the rear wiper motor has a good ground connection. A poor ground can cause circuit failures.
• Inspect the Control Switch:
• Check the rear wiper switch on the dashboard for proper operation. A faulty switch can send incorrect signals to the relay.
• Scan for Additional Codes:
• Use an OBD-II scanner to check for any additional trouble codes that may provide more context to the issue.
• Check for Short Circuits:
• Inspect the wiring for any signs of short circuits or open circuits that could affect the relay coil circuit.
• Consult a Professional:
• If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician for further diagnosis. By following these steps, you should be able to identify the cause of the B1818 code and take appropriate action to resolve the issue.