B1622 — Wiper Rear Low Limit Input Circuit Short To Ground
**Overview of the code**
The diagnostic trouble code B1622 indicates a problem within the electrical system controlling the **rear windshield wiper**, specifically related to the **low limit input circuit**. This circuit signals to the vehicle’s Electronic Control Unit (ECU) when the wiper is at its lowest limit position. When the ECU detects an anomaly, such as a short circuit to ground, it triggers this code.
Please note that **labeling may vary** between different vehicle manufacturers, so the exact terminology or component designation could differ slightly depending on the OEM.
**Fast Facts**
- System affected: Rear wiper control circuit
- Severity: Moderate
- Main symptoms: Wiper malfunction, warning lights, or error message
- Driveability: No (mostly related to wiper function and may not affect overall vehicle operation)
—
**Manufacturer variations for trouble code B1622**
Different vehicle manufacturers often assign their own codes or labels to similar issues. For the B1622 trouble code, OEM-specific labels or descriptions may include references to rear wiper limit signals or control circuit faults. Some notable variations include:
- Honda: PWW232 (Rear Wiper Low Limit Input Circuit Short to Ground)
- Nissan: B1622 (Rear Wiper Low Input Circuit Short to Ground)
- Volkswagen/Audi: 5F0 959 861 B (related to rear wiper limit switch circuit)
- BMW: 5A3D (Rear Wiper Circuit Fault)
Remember that each manufacturer might have their precise code or description, but they all refer to issues in the same or similar circuits.
—
**What does trouble code B1622 mean?**
Trouble code B1622 indicates that the vehicle’s ECU has detected a **short circuit to ground** in the **rear wiper’s low limit input circuit**.
**In simple terms:**
– The ECU constantly monitors the **wiper limit switch** — this is a sensor or switch that tells the vehicle when the rear wiper has reached its lowest or « home » position.
– When there is a **short to ground** in this circuit, it essentially means that the electrical connection is disrupted by an unintended direct connection to the vehicle’s chassis (ground), creating a fault.
– This short can be caused by damaged wiring, corrosion, or a faulty switch.
**The typical context of this code appearing** could include a rear wiper that stops working, erratic movement, or a warning light on the dashboard indicating a problem with the wiper system.
—
**Severity and risks of trouble code B1622**
This code generally signals a **moderate fault** affecting the rear wiper operation. The primary risk lies in the **loss of rear window visibility** in adverse weather, which could impair driver vision and safety.
However, it **does not typically** influence the vehicle’s overall drivability or safety systems.
**Can the vehicle be driven?**
Yes, but the rear wiper’s functionality might be compromised. If rear visibility is a concern, repairs should be prioritized to restore proper operation.
—
**Symptoms of trouble code B1622**
When this code is present, drivers may notice some or all of the following symptoms:
– Rear wiper not operating when activated
– Inconsistent or erratic movement of the rear wiper
– Warning lights or error messages related to the wiper system on the dash display
– Audible clicking or strange noises from the wiper motor (if wiring shorts cause motor issues)
– Potential failure to pass safety inspections due to malfunctioning rear wiping function
—
**Most likely causes of trouble code B1622**
This code arises from issues within the **rear wiper’s limit switch circuit**, primarily due to electrical faults or component failure. The probable causes, listed from most to least common, include:
1. **Wiring damage or short circuit** – Frayed wires, corrosion, or poor connectors causing a direct path to ground.
2. **Faulty rear wiper limit switch** – The switch itself may be defective, stuck, or damaged.
3. **Corroded or damaged connector / plug** – Effects of moisture or dirt causing poor contact.
4. **Wiper motor or control module defect** – Less common, but possible if internal circuitry is compromised.
5. **Miswired or incorrect component installation** – Only relevant in recent repairs or modifications.
—
**How to diagnose trouble code B1622**
Diagnosis should proceed with a methodical approach to identifying the root cause safely and accurately:
1. **Visual Inspection**
– Check wiring harnesses, connectors, and the wiring around the rear wiper assembly.
– Look for signs of damage, corrosion, fraying, or melted insulation.
2. **Examine the Wiper Limit Switch**
– Access the switch (or sensor) and inspect it for proper positioning or damage.
– Check for physical faults that could cause switching issues.
3. **Test the Wiring Continuity**
– Use a multimeter to verify continuity between the ECU connector and the switch.
– Check for shorts to ground by measuring resistance to vehicle chassis.
4. **Live Data Monitoring**
– Connect a diagnostic scanner capable of viewing live sensor data.
– Observe the signals when operating the rear wiper to verify correct input readings.
5. **Inspect Connectors and Grounds**
– Ensure that all connectors are clean, secure, and correctly seated.
– Verify grounding points for the circuit are intact and free of corrosion.
6. **Check the Wiper Motor and Control Module (if applicable)**
– Test the motor’s operation and the control module outputs if accessible and necessary.
—
**Possible repairs for trouble code B1622**
Based on the diagnostic findings, repairs may include:
– **Repair or replace damaged wiring or connectors**
*This is a basic task, often DIY-friendly but may require professional tools for some connectors.*
– **Replace the defective rear wiper limit switch**
*A straightforward replacement usually performed by a technician with proper parts.*
– **Clean or re-secure connections**
*Ensuring that all plugs and sockets are firmly attached and free of corrosion.*
– **Repair or replace the wiper motor or control module**
*More complex and generally requiring a professional technician.*
– **Address any ground connectivity issues**
*Ensuring all grounding points are solid and free of rust or dirt.*
Each repair should be tailored to the exact cause identified during troubleshooting, and safety precautions must be followed during electrical repairs.
—
**Vehicles commonly associated with trouble code B1622 in Europe**
While the exact incidence can vary, the **rear wiper circuitry fault code B1622** is more prevalent in certain vehicle makes and models. Typical vehicles include:
– **Volkswagen Group models** (e.g., Golf, Passat, Tiguan) with rear wipers controlled via a dedicated switch and sensor system.
– **Audi models** sharing similar electrical architectures.
– **Skoda** vehicles employing similar wiring diagrams.
– **SEAT** vehicles with rear wipers that include limit switch detection.
**Note:** It’s essential to refer to specific repair data for each model, as wiring and control systems can differ significantly.
—
**Frequent mistakes & best practices**
Common pitfalls during diagnosis and repair include:
– **Replacing components without confirming the root cause**, leading to unnecessary expenses.
– **Overlooking wiring or connector issues**—many problems originate from simple wiring faults.
– **Using incorrect or damaged test equipment**, which can provide misleading readings.
– **Not securing grounding points properly**, which can cause persistent electrical faults.
– **Ignoring manufacturer-specific procedures**, risking misdiagnosis or damage.
**Best practices:**
– Always perform thorough visual inspections before testing.
– Follow multi-step diagnostic procedures to avoid jumping to conclusions.
– Use the correct service information and wiring diagrams.
– Test components in the vehicle’s circuit rather than replacing parts blindly.
—
**FAQ — trouble code B1622**
**Can this code disappear on its own?**
Unlikely. This code signifies an electrical fault that needs correction. It may clear temporarily if the fault is intermittent, but persistent issues will cause it to return.
**Can I keep driving?**
Yes, but with caution. The rear wiper might not function correctly, or warning lights might remain active. If rear visibility is critical, prioritize repairs.
**Why does the code return after clearing?**
The underlying fault persists, such as damaged wiring, a faulty switch, or a short circuit. Simply resetting the code won’t solve the problem unless the root cause is addressed.
—
This comprehensive guide aims to help both DIY enthusiasts and professional technicians understand the nature, causes, and remedies associated with trouble code B1622. Proper diagnosis and corrective action will ensure restored functionality and safe vehicle operation.