B1620 — Wiper Rear Low Limit Input Circuit Open #

Note: The code description may vary depending on the vehicle manufacturer (OEM). Here are known variations of the B1620 code label:

• Rear Wiper Low Limit Input Circuit/Open (Chrysler, Jeep, Dodge)
• Wiper Rear Low Limit Input Circuit Malfunction (Ford, Lincoln)
• Rear Wiper Park Position Circuit Open (Toyota, Lexus)

Summary of B1620 #

The B1620 trouble code indicates that the vehicle’s control module has detected an open circuit condition in the rear wiper low limit input. In simple terms, the control module (often called the Body Control Module or BCM) is no longer receiving the expected electrical signal from the switch or sensor that tells it when the rear wiper is in its “parked” or lowest position. This circuit is essential for the correct operation and resting of the rear wiper blade. When this signal is lost, the rear wiper may not operate as intended, may stop in the wrong position, or may not function at all. The code serves as a diagnostic pointer to electrical or component faults within the rear wiper system.

Frequent Symptoms for Code B1620 #

When the B1620 code is present, certain symptoms may become obvious to the driver or technician. While some vehicles might only show a warning light, others could experience more pronounced issues. Typical symptoms include:

• Rear wiper does not return to its proper resting (“park”) position
• Rear wiper stops mid-sweep or in an unusual position
• Rear wiper fails to operate when switched on
• Intermittent or erratic rear wiper behavior
• Warning light or message on the dashboard (often a general “wiper system” indicator or a body/electrical warning)

Probable Causes for Code B1620 #

The causes for a B1620 are typically related to the electrical circuit or the components involved in signaling the rear wiper’s low (parked) limit. The most common root causes, in order of likelihood, are:

1. Open or damaged wiring between the rear wiper motor/switch and the control module
2. Faulty rear wiper park limit switch or integrated sensor (often built into the wiper motor assembly)
3. Corroded or loose electrical connectors at the wiper motor, switch, or module
4. Defective rear wiper motor assembly (if the limit switch is internal)
5. Body Control Module (BCM) failure (rare)

Step-by-Step Diagnosis for B1620 #

To accurately diagnose a B1620 code, a systematic approach is essential. Here’s a step-by-step process:

1. Check for other related trouble codes (especially body or wiper system codes).
2. Verify rear wiper operation using the wiper switch. Note any abnormal behavior.
3. Inspect the wiring harness and connectors between the rear wiper motor and the BCM for obvious damage, corrosion, or disconnects.
4. Test the park/limit switch (or the sensor within the wiper motor) for continuity with a multimeter while manually moving the wiper arm.
5. Measure voltage at the rear wiper motor and at the park limit switch input with the ignition on and wiper engaged.
6. If all wiring and switch/sensor tests pass, check the BCM’s input pin for function using scan tools or back-probing.
7. Consult OEM wiring diagrams to confirm correct circuit routing.
8. If no fault is found elsewhere, consider a faulty BCM as a last resort.

Possible Repairs for Code B1620 #

Once the underlying cause is identified, repairs are typically straightforward and tied directly to the diagnostic findings:

• Repair or replace damaged wiring between the rear wiper assembly and the BCM
• Clean or reconnect corroded or loose connectors at the wiper motor or control module
• Replace the rear wiper park limit switch or rear wiper motor assembly (if the switch is internal)
• Update or reprogram the BCM software (check for technical service bulletins from the OEM)
• In rare cases, replace the Body Control Module (BCM)

Can You Drive with Code B1620? #

Limited: You can generally continue driving with a B1620 code, as it does not affect the critical operation of your vehicle. However, rear visibility during rain or snow may be compromised if the wiper does not function properly or parks in the driver’s field of view. If you rely on the rear wiper for safety, especially in adverse weather, it’s best to address the issue promptly.

Vehicles Most Commonly Affected by B1620 #

The B1620 code is most frequently encountered on vehicles where the rear wiper system is electronically controlled by the BCM. It is especially common in certain brands and models, including:

• Chrysler, Dodge, Jeep SUVs and minivans (e.g., Grand Cherokee, Town & Country, Journey)
• Ford and Lincoln SUVs (e.g., Explorer, Expedition, Navigator)
• Toyota and Lexus crossovers (e.g., RAV4, RX series)
• Some GM SUVs and hatchbacks
• Volkswagen and Audi wagons with rear wipers

Common Mistakes & Best Practices for Code B1620 #

When troubleshooting a B1620 code, certain pitfalls can slow down the repair or lead to misdiagnosis. Here’s what to avoid and best practices to follow:

• Assuming the wiper motor is faulty without checking wiring and the limit switch first
• Overlooking connector corrosion, especially in wet climates or after car washes
• Skipping a full scan for related codes (there may be more than one electrical issue)
• Neglecting to consult OEM wiring diagrams for the correct circuit path
• Always clear codes and perform a functional test after repairs

Quick FAQ for B1620 #

If you have questions about the B1620 code, you’re not alone. Here are answers to the most common queries:

• Q: Will my rear wiper start working again if I clear the code?
• A: Clearing the code alone will not restore wiper function; the underlying electrical or component issue must be repaired first.
• Q: Can a bad BCM cause other unrelated electrical problems?
• A: Yes, since the BCM manages many body functions, a failing module may trigger multiple codes or erratic behaviors across different systems.
• Q: Is this an expensive repair?
• A: Most B1620 fixes (wiring, connectors, switches) are relatively affordable. Replacing the BCM is rare and more costly, but seldom needed for this code.