B1336

What Does Code B1336 Mean?

DTC B1336 signifies an “Open Circuit” condition within the electrical monitoring system for the rear right (RR) door ajar switch. This diagnostic trouble code is typically registered by the Body Control Module (BCM), or an equivalent integrated body computer such as a Smart Junction Box (SJB) or General Module, rather than the Powertrain Control Module (PCM/ECM). The BCM continuously monitors the state of all door ajar switches to determine if a door is open or closed. A door ajar switch typically functions by completing or breaking a low-current electrical circuit when the door is opened or closed, sending a specific voltage signal (e.g., ground or battery voltage) to the BCM. An “Open Circuit” indication means the BCM is not detecting the expected electrical continuity or voltage signal from the rear right door ajar switch circuit when it should, suggesting a complete interruption of the electrical path. This could be interpreted by the BCM as the door always being open, or more fundamentally, that the circuit itself is non-functional, preventing any accurate status reporting.

Common Symptoms

• The rear right door ajar warning light on the instrument cluster remains illuminated, even when the door is securely closed.
• Interior dome lights or courtesy lights fail to extinguish after the rear right door is closed and all other doors are secured.
• A continuous or intermittent audible chime or warning sound indicating an open door, despite the rear right door being fully latched.
• The vehicle’s security system may malfunction, potentially failing to arm, setting off false alarms, or preventing remote locking due to the perceived open door.
• In some vehicle models, specific power functions related to the rear right door (e.g., window operation, child safety locks) may be inhibited if the BCM interprets the door as perpetually open.

What Causes the Code B1336?

• Faulty Rear Right Door Ajar Switch: The most common cause is a defective door ajar switch itself. The switch, often integrated into the door latch assembly, may be mechanically stuck in an “open” position, have internal electrical contacts that are corroded or worn out, or suffer from complete electrical failure.
• Damaged Wiring Harness: A break, fray, or compromise in the electrical wiring leading to or from the rear right door ajar switch. This damage frequently occurs in the flexible wiring conduit that passes between the door frame and the door pillar, where wires are subjected to repeated bending and stress.
• Corrosion or Loose Electrical Connectors: Oxidation, rust, or poor pin tension at the electrical connectors for the rear right door ajar switch, the main body-to-door harness connector, or even at the BCM connector, can lead to high resistance or an intermittent/permanent open circuit condition.
• Malfunctioning Body Control Module (BCM): While less frequent, an internal failure within the BCM that impairs its ability to accurately read the input signal from the rear right door ajar switch can trigger this code. This should typically be diagnosed as a last resort after ruling out external circuit issues.

How to Diagnose and Troubleshoot

Diagnosis of B1336 requires a systematic approach, often leveraging a Digital Multimeter (DMM) and an advanced OBD-II scanner:

1. Visual Inspection:
   • Begin with a thorough visual inspection of the rear right door jamb area. Look for any obvious physical damage to the door ajar switch (often part of the door latch mechanism), as well as the flexible wiring conduit connecting the door to the vehicle body.
   • Carefully inspect the wiring within the conduit for signs of pinching, cuts, abrasions, or frays. These are common points of failure due to repeated opening and closing of the door.
   • Check for evidence of water intrusion, excessive dirt, or corrosion around the door latch assembly and any visible electrical connectors.
2. OBD-II Scanner Live Data Analysis:
   • Connect an OBD-II scanner capable of accessing BCM/chassis codes and live data streams.
   • Navigate to the live data parameters related to “Door Ajar Status” or similar inputs. Specifically monitor the “Rear Right Door” status.
   • Manually open and close the rear right door while observing the live data. If the status remains perpetually “Open,” “Unknown,” or does not change, it strongly indicates a circuit or switch problem.
3. Digital Multimeter (DMM) Testing:
   • Switch Continuity Test: Locate and disconnect the electrical connector for the rear right door ajar switch. Using a DMM set to continuity (audible beep) or resistance (Ohms), test the switch directly. Operate the door latch mechanism manually to simulate the door being opened and closed. A functional switch should show a clear change in state (e.g., continuity when closed, open circuit when open, or vice-versa, depending on the switch design). An “Open Circuit” code suggests the switch may always show an open circuit regardless of its mechanical position, or it fails to close when it should.
   • Wiring Integrity Check: With the door ajar switch disconnected and, if necessary, the corresponding BCM connector disconnected (always refer to the vehicle’s specific wiring diagrams for pinouts and BCM location), use the DMM to check for continuity of the wires from the door switch connector back to the BCM connector. Also, check each wire for a short to ground or a short to power. A high resistance reading or a complete open circuit on one of the wires confirms a wiring fault. The flexible boot area is a common culprit.
   • Voltage and Ground Supply: With the ignition ON (and switch disconnected), check the door ajar switch connector for appropriate reference voltage (typically 5V or 12V) and a good ground connection, as specified in the vehicle’s wiring diagram. An absence of expected voltage or ground indicates a wiring issue originating from the BCM or an internal BCM fault.

Recommended Repairs and Solutions

Based on diagnostic findings, the following repairs are typically recommended:

• Replace Faulty Door Ajar Switch: If DMM testing unequivocally confirms the door ajar switch is internally defective, stuck, or not changing states, replacement is necessary. In many modern vehicles, the door ajar switch is an integral part of the door latch assembly, meaning the entire latch mechanism will need to be replaced. Ensure the replacement part is specific to the vehicle’s make, model, and year.
• Repair or Replace Damaged Wiring: If the diagnostic steps identify a broken, frayed, or compromised wire within the harness, perform a professional repair. This involves stripping back insulation, soldering new wire sections using proper techniques, and protecting the repair with heat-shrink tubing. For extensive damage, especially within the door jamb conduit, it may be more practical and reliable to replace the entire damaged section of the wiring harness or the complete door harness assembly.
• Clean Corroded Connectors: If corrosion is found on any electrical connectors, disconnect them carefully. Use a specialized electrical contact cleaner and a small, non-abrasive brush to thoroughly clean all terminal pins. After ensuring the connectors are dry, apply a thin layer of dielectric grease to prevent future corrosion and improve electrical conductivity before reassembling.
• Body Control Module (BCM) Replacement: Only consider replacing the BCM as a last resort, after thoroughly verifying the integrity and functionality of the door ajar switch and all associated wiring. BCM failures are relatively uncommon for this specific code. BCM replacement often requires specialized programming or coding to the vehicle’s immobilizer and other systems using a factory-level scan tool, which can be an involved and costly procedure. Always consult vehicle-specific service information for BCM replacement and programming procedures.