B1537

What Does Code B1537 Mean?

DTC B1537 signifies an electrical fault within the “Memory 2 Switch Circuit” where the Body Control Module (BCM) or a specialized control module (such as a Driver Seat Module, DSM) detects a “Short To Battery.” As a “B” code, it indicates a problem within the vehicle’s body electrical system, specifically related to convenience features rather than the powertrain. The “Memory 2 Switch Circuit” typically refers to the input circuit associated with the second stored memory position for features like power seats, exterior mirrors, or steering column adjustments. When the control module monitors this circuit, it expects to see a specific voltage level or an open circuit state when the Memory 2 switch is not activated. A “Short To Battery” means the module is receiving a voltage signal on this circuit that is at or near the vehicle’s battery voltage (approximately 12V) at all times, regardless of the switch’s actual position. This abnormal voltage prevents the module from correctly interpreting the switch’s state, leading to a functional impairment of the associated memory feature and setting the diagnostic trouble code.

Common Symptoms

• Inoperative or intermittent functionality of the “Memory 2” preset for seats, mirrors, or steering column.
• Complete loss of all memory functions, even for other presets.
• Memory seat, mirror, or steering column moving to an incorrect or random position.
• Warning messages on the instrument cluster related to memory features or general electrical faults.
• In rare cases, a constant draw on the battery if the short involves a constantly powered circuit, though this is less common for switch input circuits.
• No perceptible symptoms other than the stored DTC, particularly if the short is intermittent or the module has fail-safe modes.

What Causes the Code B1537?

• Damaged Wiring Harness: The most frequent cause involves the wiring connected to the memory switch. A wire in the “Memory 2 Switch Circuit” may be chafed, pinched, or otherwise damaged, causing it to short directly to an adjacent constant or switched 12V power supply wire within the harness.
• Faulty Memory Switch Assembly: An internal short circuit within the memory switch itself can cause the output terminal for “Memory 2” to be continuously connected to the switch’s 12V power input, even when the switch is not pressed.
• Corrosion in Connectors: Moisture ingress or environmental factors can lead to corrosion within the wiring connectors associated with the memory switch or the control module, creating an unintended conductive path (short) to a battery voltage source.
• Improper Aftermarket Accessory Installation: Incorrectly installed aftermarket electronics (e.g., alarms, lighting, entertainment systems) that tap into the vehicle’s wiring can inadvertently cause a short to battery voltage on the memory switch circuit.
• Control Module Internal Fault: While less common for a direct “short to battery” code, an internal defect within the BCM, DSM, or other related control module could erroneously report this fault or have an internal component failure that creates an artificial short.

How to Diagnose and Troubleshoot

Diagnosing B1537 requires meticulous electrical testing and adherence to the vehicle manufacturer’s wiring diagrams.

1. Initial Scan and Data Analysis: Connect an OBD-II scanner to confirm the presence of DTC B1537. Check for any related body codes that might offer additional clues. Examine freeze frame data to understand the operating conditions when the code was set.
2. Visual Inspection:
   • Visually inspect the wiring harness leading to the memory switch (often located on the driver’s door panel or seat side) for any signs of damage such as chafing, pinching, cuts, or rodent activity.
   • Examine the electrical connectors at the memory switch and the relevant control module (BCM/DSM). Look for corrosion, bent pins, pushed-back terminals, or loose connections.
3. Wiring Diagram Analysis: Obtain the precise wiring diagram for your vehicle’s memory seat/mirror/steering system. Identify the specific wire for the “Memory 2 Switch Circuit” that reports to the control module. Note its pin assignments at both the switch and module connectors.
4. Digital Multimeter (DMM) Testing at the Switch Connector:
   • Disconnect Battery: For safety and to prevent further damage, disconnect the vehicle’s negative battery terminal.
   • Isolate the Switch: Disconnect the electrical connector from the memory switch assembly.
   • Voltage Check (Ignition ON): Reconnect the battery. With the ignition in the “RUN” position, use a DMM to measure voltage on the “Memory 2 Switch Circuit” wire (as identified by the wiring diagram) at the harness side of the disconnected switch connector. There should typically be no battery voltage present on this signal wire unless the switch is designed to provide it through an internal resistor ladder network when pressed. If you measure battery voltage, it indicates a short to battery voltage in the wiring harness itself, upstream of the switch.
   • Continuity Check (Battery Disconnected): With the battery disconnected and both the switch and control module connectors disconnected, perform a continuity test using the DMM. Test for continuity between the “Memory 2 Switch Circuit” wire (at the harness connector) and known 12V power supply wires (e.g., constant B+ or switched ignition power wires) within the same harness. Also, test for continuity to chassis ground. If continuity exists to a power wire, you have confirmed a short in the harness.
5. Memory Switch Internal Testing:
   • If the wiring harness tests clear, the fault likely lies within the memory switch itself. Remove the memory switch assembly from the vehicle.
   • Using the wiring diagram, identify the input and output terminals for the “Memory 2” function. Use the DMM to test continuity or resistance across these terminals as you activate the “Memory 2” button, following manufacturer specifications. Look for a constant short between a 12V input terminal and the “Memory 2” signal output terminal, even when the switch is in its resting state.
6. Control Module Isolation: If all other tests yield no definitive fault, and only as a last resort, disconnect the control module (BCM/DSM) to see if the short disappears on the circuit. This might indicate an internal fault within the module, though this is rare for a direct “short to battery” code.

Recommended Repairs and Solutions

Once the root cause of the B1537 code has been identified through systematic diagnosis, the following repairs can be performed:

• Repair or Replace Damaged Wiring: If the diagnostic steps indicate a short to battery in the wiring harness, carefully locate the exact point of damage. Repair the damaged section using OEM-approved wiring repair methods, including soldering, heat-shrink tubing, and appropriate gauge wire. If the damage is extensive or in a difficult-to-access area, it may be more efficient to replace the entire sub-harness. Ensure all repaired sections are properly insulated and secured to prevent future damage.
• Replace Faulty Memory Switch Assembly: If internal testing of the memory switch confirms a short or malfunction, replace the entire memory switch unit with a new OEM or equivalent aftermarket part. Ensure the new switch is properly installed and its connector is securely fastened.
• Clean or Replace Corroded Connectors/Terminals: If corrosion is found on connectors or terminals, disconnect the battery, thoroughly clean the affected areas using electrical contact cleaner and a small brush. Inspect for permanent damage to the terminals; if present, replace the affected terminals or the entire connector housing. Apply dielectric grease to prevent future corrosion.
• Address Aftermarket Wiring Issues: If aftermarket accessories are implicated, temporarily disconnect them. If the code clears, carefully inspect and repair any improperly made splices or connections. Ensure all aftermarket wiring is correctly installed, fused, and isolated from critical vehicle circuits.
• Control Module Replacement (Last Resort): Only if all other components (wiring, switch, connectors) have been thoroughly tested and ruled out, and specific diagnostic procedures point to an internal module fault, consider replacing the BCM, DSM, or relevant control module. Be aware that control module replacement often requires programming or configuration using specialized diagnostic tools, which may necessitate a visit to a dealership or a shop with advanced capabilities.
• Clear DTCs and Verify Repair: After any repair, clear all diagnostic trouble codes using an OBD-II scanner. Then, perform a functional test of the memory system (e.g., activating and deactivating memory presets) to ensure the issue is resolved and the system operates as intended. Drive the vehicle and re-scan to confirm the code does not return.