B1819 — Wiper Rear Motor Up Relay Coil Circuit Open #

Note: The description for DTC B1819 may vary depending on the manufacturer. Always refer to the OEM (Original Equipment Manufacturer) documentation for the most accurate terminology.

• Ford: Rear Wiper Motor Up Relay Circuit Open
• Toyota: Rear Wiper Motor Relay (UP) Circuit Open
• Honda: Rear Wiper Motor Up Relay Coil Open Circuit

Summary of DTC B1819 #

The B1819 trouble code is linked to the electrical circuit controlling the rear wiper motor’s “up” relay. This relay is responsible for moving the rear wiper blade into its resting (parked) position when not in use. When the vehicle’s control module detects an open or interrupted circuit in the relay coil, it sets this code. An open circuit means the electrical path is broken, preventing current flow. While this issue rarely causes immediate safety risks, it can affect rear visibility in wet or dusty conditions. The code typically points to a wiring problem, relay failure, or an issue with the wiper motor assembly itself.

Frequent Symptoms for the B1819 Code #

Drivers or technicians may notice several signs when the B1819 code is present. While some symptoms are subtle, others can impact your day-to-day driving experience—especially in adverse weather. Here’s what to look out for:

• Rear wiper does not return to its parked position after use.
• Rear wiper remains stuck mid-sweep or at an unusual angle.
• Rear wiper is nonfunctional when activated.
• Intermittent or inconsistent rear wiper operation.
• Warning light or message on dashboard (in some vehicles).

Probable Causes for B1819 (Most to Least Common) #

An open circuit in the rear wiper up relay coil may stem from several root causes. Understanding these helps you prioritize diagnosis and repair, saving time and unnecessary part replacements. Here’s what most commonly triggers DTC B1819:

1. Faulty rear wiper relay (internal coil failure or burned contacts).
2. Broken, corroded, or disconnected wiring in the relay control circuit.
3. Defective rear wiper motor assembly (especially if the relay is integrated).
4. Damaged or loose relay socket/connector.
5. Faulty control module (Body Control Module or equivalent, rare).

Step-by-Step Diagnostic Process for B1819 #

Diagnosing an open relay coil circuit is a methodical process. By following these steps, you can isolate the issue efficiently—whether you’re a DIYer or a professional technician. Here’s a recommended workflow:

• Verify the code using a scan tool and clear any stored codes. Test the wiper function to confirm symptoms.
• Inspect the rear wiper relay—locate it using the OEM wiring diagram. Remove and test the relay for continuity across the coil terminals with a multimeter.
• Check the wiring and connectors from the relay to the rear wiper motor and control module. Look for corrosion, broken wires, or loose connections.
• Test for power and ground at the relay socket while operating the rear wiper switch.
• Bench-test the rear wiper motor if accessible, ensuring it moves through all cycles.
• Substitute a known-good relay to rule out relay failure.
• If wiring and relay are good, consider control module testing or seek professional help.

Possible Repairs for the B1819 Code #

After pinpointing the cause, repairs should directly address the faulty component or connection. Here’s what you might need to do, depending on your findings:

• Replace the rear wiper relay if testing shows an open coil or internal failure.
• Repair or replace damaged wiring or connectors in the relay circuit.
• Clean or tighten relay sockets and connector pins if signs of corrosion or looseness are found.
• Replace the rear wiper motor assembly if internal issues are confirmed (especially if relay is integrated).
• In rare cases, reprogram or replace the control module (after all other causes have been ruled out).

Can You Drive with Code B1819? #

Yes, but with limitations. While B1819 does not directly affect engine performance or major safety systems, driving with a nonfunctional rear wiper can compromise rear visibility—especially in rain, snow, or dusty conditions. If your local weather is fair, short-term driving is possible, but prompt repair is recommended to restore full rearward vision and maintain safety.

Vehicles Most Commonly Affected by B1819 #

This code is seen across various makes and models, especially those with rear wipers controlled by relay-based circuits. Vehicles from the following brands and platforms are most frequently reported with B1819:

• Ford: Focus, Escape, Explorer, Edge
• Toyota: RAV4, Highlander, Sienna
• Honda: CR-V, Odyssey, Pilot
• Mazda: CX-5, CX-9
• Hyundai/Kia: Santa Fe, Sorento

Common Mistakes & Best Practices for B1819 Diagnosis #

Even experienced technicians occasionally misdiagnose this code. Avoid these pitfalls and follow best practices for an efficient, accurate repair:

• Replacing the wiper motor or relay without testing the circuit—always verify with a multimeter first.
• Overlooking corroded connectors in the rear hatch (common in older or wet-climate vehicles).
• Ignoring intermittent issues—wiggle-test wiring and connectors to catch hidden breaks.
• Skipping OEM wiring diagrams—circuit layouts vary significantly by make/model.

Express FAQ — B1819 #

Q: Will clearing the code make my rear wiper work again?
A: Clearing the code will not restore function if the underlying fault remains. The circuit must be repaired for normal operation.

Q: Is this a DIY-friendly repair?
A: Checking the relay and connectors can often be done at home with basic tools. However, if the problem is within the wiring harness or control module, professional diagnosis is recommended.