B1536

What Does Code B1536 Mean?

DTC B1536, “Memory 2 Switch Circuit Open,” indicates a detected electrical anomaly within the circuit associated with the second memory preset switch, typically found in a vehicle’s power seat memory system. This code is classified as a Body (B) code, meaning it pertains to the body electrical systems rather than the powertrain, chassis, or network. The Body Control Module (BCM) or a dedicated Driver Seat Module (DSM) is responsible for monitoring the electrical integrity of these circuits. When the control module detects an absence of expected voltage, resistance, or continuity across the “Memory 2” switch circuit—interpreting this as an open circuit condition—it sets DTC B1536. This signifies a break or interruption in the electrical path, preventing the module from properly reading the switch’s input signal, which is critical for saving or recalling a specific driver’s preferred seat, mirror, and potentially steering column positions for the second memory slot.

Common Symptoms

• Inability to save or recall the “Memory 2” preset for the driver’s seat.
• The “Memory 2” button or switch is unresponsive when pressed.
• Intermittent functionality of the seat memory system, particularly affecting the second preset.
• Other related memory functions (e.g., mirrors, steering column) might also be affected if their control signals are multiplexed through the same switch circuit or module.
• A “Check System” or specific body electrical warning indicator may illuminate on the instrument cluster, depending on the vehicle’s specific warning hierarchy.

What Causes the Code B1536?

• Faulty Memory 2 Switch: The most direct cause, where the internal contacts of the switch itself have failed, corroded, or are mechanically broken, creating an open circuit within the switch.
• Open Circuit in Wiring Harness: A physical break, fray, or compromise in the electrical wiring connecting the Memory 2 switch to the Body Control Module (BCM) or Driver Seat Module (DSM). This is common in areas subjected to frequent movement, such as under the seat or within the door panel.
• Corroded or Loose Electrical Connectors: Inadequate electrical contact at the connector terminals for the Memory 2 switch or at the module itself due to corrosion, improper seating, or physical damage.
• Damaged Wiring from External Factors: Accidental damage to the wiring harness from objects under the seat, spills, or previous service activities.
• Faulty Driver Seat Module (DSM) or Body Control Module (BCM): While less common for a specific “open circuit” fault, an internal defect within the control module responsible for monitoring the switch input could incorrectly interpret the circuit status or fail to provide proper reference voltage.

How to Diagnose and Troubleshoot

A systematic diagnostic approach is crucial for resolving B1536. Begin by utilizing an advanced diagnostic scanner capable of reading B-codes and accessing specific Body Control Module (BCM) or Driver Seat Module (DSM) data PIDs.

1. Retrieve & Document DTCs: Use the scanner to confirm B1536 is present. Check for any associated or pending codes that might provide further insight into the affected system. Record all freeze-frame data.
2. Visual Inspection:
   • Inspect the Memory 2 switch itself for any obvious physical damage, loose components, or obstructions.
   • Carefully examine the wiring harness leading to the switch and under the seat for signs of chafing, pinching, cuts, or corrosion. Pay close attention to areas where wiring passes through seat frames or hinges.
   • Check the electrical connectors at the Memory 2 switch and the relevant control module (BCM/DSM) for security, corrosion, or bent/pushed-out pins.
3. Consult Wiring Diagrams: Obtain the vehicle-specific wiring diagram for the driver’s seat memory system. Identify the power, ground, and signal wires for the Memory 2 switch. This is essential for accurate multimeter testing.
4. Electrical Circuit Testing with a Digital Multimeter (DMM):
   • Disconnect Battery/Relevant Fuse: For safety, disconnect the vehicle’s negative battery terminal or remove the fuse protecting the seat memory circuit before performing continuity checks.
   • Switch Continuity Test: Disconnect the electrical connector from the Memory 2 switch. Using the DMM in continuity or resistance mode, test across the terminals of the switch. Actuate the switch to confirm it opens and closes the circuit correctly and displays expected resistance values (e.g., near 0 ohms closed, infinite open).
   • Harness Continuity Test (Open Circuit): With the switch disconnected and the battery still disconnected, use the DMM to check for continuity of the wiring harness from the switch connector back to the corresponding pins on the BCM/DSM connector. An “open circuit” will register as infinite resistance (OL). This test will pinpoint any breaks in the wiring.
   • Voltage Supply Test: Reconnect the battery. With the switch connector still disconnected (or back-probed carefully), verify proper voltage supply (typically 12V or a specific reference voltage from the module) to the switch’s power input terminal and a good ground connection at the ground terminal (if applicable) using the DMM.
   • Signal Wire Voltage Test: If the switch sends a variable voltage signal, observe the signal wire voltage at the module’s connector while actuating the switch (if possible by back-probing safely).
5. Wiggle Test: With the system powered and live data monitored (if the scanner offers switch status PIDs), gently wiggle the wiring harness and connectors while observing for intermittent changes in switch status or voltage readings.

Recommended Repairs and Solutions

Once the root cause of the B1536 code has been identified through thorough diagnosis, implement the following repairs:

1. Replace Faulty Memory 2 Switch: If the DMM tests confirm the Memory 2 switch itself is internally defective and not making proper contact, replace it with an OEM or equivalent quality aftermarket part. Ensure the new switch functions correctly after installation.
2. Repair or Replace Damaged Wiring: If an open circuit is located within the wiring harness, the damaged section must be professionally repaired. Use appropriate automotive-grade wire, solder connections, and insulate with heat-shrink tubing for a durable, weather-resistant repair. Avoid relying solely on crimp connectors in critical circuits. For extensive or severely damaged sections, it may be more efficient to replace the entire sub-harness.
3. Clean and Secure Electrical Connectors: If corrosion is present on connector terminals, clean them thoroughly using an electrical contact cleaner and a small brush. Ensure all connectors are fully seated and latched, and that no pins are bent or pushed out. Apply a small amount of dielectric grease to prevent future corrosion.
4. Replace Driver Seat Module (DSM) or Body Control Module (BCM): This should be considered a last resort. If all wiring, switch, and power/ground circuits test perfectly, and the module is proven to be faulty through specific diagnostic tests (e.g., internal component failure detected via bidirectional control or further diagnostic steps suggested by the manufacturer), then the module may require replacement. Be aware that module replacement often necessitates reprogramming or coding to the vehicle’s specifications using specialized diagnostic tools.
5. Clear DTCs and Verify Repair: After any repair, clear the stored DTCs using the OBD-II scanner. Then, extensively test the Memory 2 function by saving new positions and recalling them multiple times to ensure the fault does not return. Operate the vehicle for a drive cycle to confirm the system’s long-term stability.