B1245 — Wiper Rear Motor Run Relay Circuit Short to Battery #

Note: The wording for DTC B1245 may differ depending on the vehicle manufacturer. Always refer to your OEM repair manual for the exact description as applied to your vehicle.

• Rear Wiper Motor Run Relay Circuit Shorted to Battery (Ford, Lincoln, Mercury)
• Rear Wiper Relay Circuit High (Toyota, Lexus)
• Wiper Rear Motor Relay Circuit Short to Battery (GM/Chevrolet/Buick/Opel)

Summary for DTC B1245 #

DTC B1245 indicates that the vehicle’s onboard diagnostic system has detected an electrical short to battery voltage in the rear wiper motor run relay circuit. The relay is an electronic switch that allows the body control module (BCM) or other control units to manage power to the rear wiper motor. A “short to battery” occurs when a circuit wire unintentionally connects to battery voltage, causing unexpected operation or system faults. This condition can compromise rear wiper function, potentially leading to safety concerns in poor weather. Prompt diagnosis and repair are recommended to restore proper operation and avoid possible damage to related electrical components.

Common Symptoms for Code B1245 #

When B1245 is present, you may notice unusual behavior from the rear wiper system. The rear wiper might operate unpredictably, not respond to the switch, or refuse to turn off. Sometimes, there are no obvious symptoms other than the warning light or trouble code stored in the system memory.

• Rear wiper runs continuously, even when switched off
• Rear wiper does not activate at all
• Intermittent rear wiper operation
• Rear wiper responds slowly or erratically to controls
• Warning light or message on dashboard (e.g., “Check Rear Wiper System”)
• Possible battery drain if wiper stays on with ignition off

Most Likely Causes for B1245 #

Several issues can trigger a B1245 code, but some are more common than others. Typically, the root cause involves electrical faults within the rear wiper circuit, especially those that allow battery voltage to leak where it shouldn’t. Here’s what technicians usually find, ranked by frequency:

1. Damaged or shorted wiring harness for the rear wiper motor or relay
2. Faulty rear wiper relay (sticking internally or shorted contacts)
3. Corroded or water-intruded relay/fuse box (especially in hatch/trunk area)
4. Rear wiper motor failure (internal short)
5. Control module fault (rare, but possible if the module’s output circuit is damaged)
6. Incorrect installation or aftermarket wiring modifications

Step-by-Step Diagnostic Guide for B1245 #

Diagnosing B1245 requires a careful, methodical approach to avoid missing hidden wiring faults or replacing expensive components unnecessarily. Always begin by checking the basics before diving deeper:

• Consult the vehicle’s wiring diagram for the rear wiper circuit (OEM manual recommended)
• Visually inspect the wiring harness and connectors at the rear wiper motor and relay for damage, corrosion, or pinched wires
• Check the rear wiper relay for correct operation; swap with a known-good relay if possible
• Using a digital multimeter, test for battery voltage at the relay control and load circuits with the wiper off; voltage should not be present on the output when the system is off
• Disconnect the rear wiper motor and check for short-to-power or continuity between power and ground circuits
• Inspect the relay/fuse box for signs of water intrusion or corrosion, especially in vehicles with rear hatch leaks
• If all external circuits are good, consider testing the body control module (BCM) output and related grounds, following OEM procedures

Possible Repairs for B1245 #

The right repair for B1245 depends on your diagnostic findings. Always address the root cause rather than simply clearing the code. Common solutions include:

• Repair or replace damaged wiring or connectors in the rear wiper circuit
• Replace a faulty rear wiper relay with an OEM-approved part
• Clean or replace the relay/fuse box if corrosion or water damage is found
• Replace the rear wiper motor if it’s found to be internally shorted
• Correct any improper installations or aftermarket wiring modifications
• In rare cases, replace the body control module (BCM) if it’s confirmed defective

Is It Safe to Drive With a B1245 Code? #

Yes, but with limitations. While a B1245 code usually won’t cause immediate drivability issues or engine damage, it can compromise rear visibility in bad weather. If the rear wiper runs continuously, it could also wear out prematurely or drain the battery if left unchecked. For safety and peace of mind, have the issue inspected and repaired as soon as possible, especially if you rely on your rear wiper in rainy or snowy conditions.

Vehicles Most Commonly Affected by B1245 #

While B1245 can appear on many makes and models equipped with rear wipers, it’s most often reported on vehicles where the rear wiper relay and wiring are exposed to moisture or mechanical stress, such as hatchbacks, SUVs, and wagons. Here are some typical examples:

• Ford Escape, Ford Explorer, Ford Edge
• Toyota RAV4, Toyota Highlander
• Chevrolet Equinox, GMC Terrain
• Honda CR-V, Honda Pilot
• Nissan Rogue, Nissan Murano
• Subaru Outback, Subaru Forester
• Hyundai Santa Fe, Kia Sorento

Common Mistakes & Best Practices for B1245 #

Technicians and DIYers sometimes overlook key steps or make assumptions when troubleshooting B1245. To improve your odds of a first-time fix, keep these in mind:

• Don’t replace the wiper motor or relay without first checking wiring for shorts or corrosion.
• Always use OEM wiring diagrams and relay locations—wiring color codes and layouts vary between automakers and model years.
• Look for water leaks or evidence of moisture, especially in tailgates or trunk areas.
• Clear the code after repairs and verify rear wiper operation in all modes before returning the vehicle to service.
• Document your diagnosis and repairs for future reference.

Quick FAQ for DTC B1245 #

Q: Can I just pull the fuse to stop the rear wiper?
A: Pulling the fuse will disable the rear wiper, but it’s only a temporary solution. The underlying electrical fault may affect other circuits or cause further problems. It’s best to properly diagnose and repair the issue.

Q: Will B1245 turn off my check engine light?
A: Typically, B1245 is a body control code and may trigger a warning message or light related to the body system, not the main check engine light. However, some vehicles group all warning lights together, so it may still illuminate the dashboard. Always check your owner’s manual for details.