B1316

What Does Code B1316 Mean?

DTC B1316 indicates that the vehicle’s Powertrain Control Module (PCM), Body Control Module (BCM), or Generic Electronic Module (GEM), depending on the specific vehicle architecture, has detected a short to ground in the control circuit for the battery saver relay coil. The battery saver system is an integral part of modern vehicle electrical systems, designed to prevent parasitic battery drain by automatically de-energizing non-essential electrical accessories (such as the radio, interior lights, power windows, and accessory power outlets) after a predetermined time period or when the ignition is switched off and a door is opened. The control module supplies voltage or a ground signal to energize the relay coil, thereby closing its internal contacts to supply power to the accessories. When the module detects a continuous low resistance path to ground on the coil control circuit where it should expect a higher voltage or resistance state (e.g., when the relay is commanded off or when a pull-up voltage is present), it registers this fault. This implies that the module is unable to effectively control the activation or deactivation of the battery saver relay, potentially leading to persistent accessory power or an inability to power accessories when needed.

Common Symptoms

• Constant Battery Drain: Non-essential accessories (radio, interior lights, power windows, accessory outlets) may remain powered indefinitely after the ignition is turned off, leading to a discharged or dead battery, especially if the vehicle is parked for extended periods.
• Inoperable Accessories: Conversely, in some scenarios, the short to ground may prevent the battery saver relay from activating at all, resulting in the inability to power certain accessories even when the ignition is on.
• Warning Lights: While less common for this specific code, a general electrical system or battery warning light may illuminate on the instrument cluster if the continuous drain affects overall system voltage.
• Module Parasitic Draw: Advanced diagnostic tools may reveal an unexpectedly high parasitic current draw when the vehicle is in its “sleep” state.

What Causes the Code B1316?

• Damaged Wiring Harness: The most prevalent cause is physical damage to the wiring harness connected to the battery saver relay coil, resulting in the control wire making unintended contact with the vehicle’s chassis or another ground point. This damage can occur due to chafing, pinching, impact, or exposure to excessive heat.
• Faulty Battery Saver Relay: An internal short circuit within the relay coil itself, or between its internal terminals and the relay’s metallic housing (if applicable), can present as a short to ground on the control circuit.
• Corrosion or Water Intrusion: Corrosion within the relay socket, the associated harness connector, or the fuse/relay box can create unintended conductive paths to ground, particularly in environments exposed to moisture or road salts. Water intrusion can also bridge terminals directly.
• Faulty Control Module (PCM/BCM/GEM): In rare instances, an internal failure within the control module (e.g., a shorted driver transistor or output stage) responsible for commanding the battery saver relay can cause the output circuit to be continuously grounded or to present a shorted condition.

How to Diagnose and Troubleshoot

Diagnosis of B1316 requires a systematic approach, combining visual inspection with precise electrical testing using a digital multimeter (DMM) and a professional OBD-II scanner.

1. Initial Visual Inspection:
   • Begin by visually inspecting the battery saver relay, its wiring harness, and the associated fuse/relay box. Look for any obvious signs of damage such as chafed wires, melted insulation, corrosion on connectors, or evidence of water intrusion.
   • Trace the visible length of the wiring from the relay back towards the control module, paying close attention to areas where the harness passes through metal panels or near moving parts.
2. OBD-II Scanner Review:
   • Connect a professional scan tool and retrieve all stored DTCs, including any pending or historical codes, as these may offer additional context.
   • Note any freeze frame data associated with B1316, as this provides system parameters at the time the fault was detected.
   • If the scanner allows, attempt to command the battery saver relay ON and OFF to observe any changes in PID data or to facilitate further testing.
3. Digital Multimeter (DMM) Testing – Circuit Integrity:
   • Disconnect Battery: For safety and to prevent further damage, disconnect the negative battery terminal before performing resistance or continuity tests.
   • Isolate Relay: Remove the battery saver relay from its socket. Refer to the vehicle’s wiring diagram to identify the specific pins for the relay coil control circuit (typically pins 85 and 86).
   • Test for Short to Ground (Wiring Side):
     • With the relay removed and the control module harness disconnected (if testing the full wire run), set the DMM to the resistance (Ohms) setting.
     • Place one DMM lead on the suspected control wire pin at the relay socket and the other lead to a known good chassis ground. A reading of less than 5 Ohms indicates a direct short to ground in the wiring harness.
     • If multiple wires comprise the coil control circuit, test each wire for continuity to ground.
   • Test Relay Coil Itself:
     • Measure the resistance across the relay coil terminals (typically 85 and 86) of the removed relay. Compare this reading to the manufacturer’s specification (usually between 60-120 Ohms). An extremely low resistance (near 0 Ohms) suggests an internal short within the relay coil. An open circuit (OL or infinite resistance) indicates a broken coil.
     • Apply 12V from an external power source across the relay coil terminals to verify it clicks and changes state. Then, use the DMM to check for continuity across the switch terminals (typically 30 and 87/87a) to confirm proper switching action.
   • Check Control Module Output:
     • If the wiring and relay test good, the issue might lie with the control module. Reconnect the battery and ensure the control module is powered.
     • With the relay still removed and the ignition in the appropriate position (or commanded via scan tool), use the DMM to measure voltage on the control wire at the relay socket relative to ground. Observe if the module’s output correctly switches between battery voltage and near 0V (or provides a switched ground) as per the system’s design. If the circuit remains continuously grounded when it should not be, and the wiring tested good, this points to a potential internal module fault.

Recommended Repairs and Solutions

Once the root cause of B1316 has been accurately identified through diagnosis, the following repairs are typically recommended:

• Repair or Replace Damaged Wiring: If the wiring harness is found to be shorted to ground, the damaged section must be repaired. This involves carefully cutting out the compromised wire, splicing in a new section of wire of the correct gauge, and sealing the connections with solder and heat-shrink tubing to ensure a durable and weatherproof repair. If the damage is extensive or involves multiple wires, replacing the entire affected harness section may be more practical. Ensure proper routing to prevent future chafing.
• Replace Faulty Battery Saver Relay: If the battery saver relay itself exhibits an internal short, open coil, or excessive resistance, it must be replaced with a new, OEM-specified relay. Always confirm the new relay’s part number and specifications match the original.
• Clean and Repair Corroded Connectors: For instances of corrosion or water intrusion, thoroughly clean the affected relay socket and harness connector terminals using a specialized electrical contact cleaner and a small brush. If terminals are severely corroded, bent, or damaged, they should be replaced using appropriate terminal repair kits. After cleaning/repair, apply dielectric grease to the connections to prevent future moisture intrusion and corrosion.
• Replace Control Module (PCM/BCM/GEM): Replacement of the control module should only be considered as a last resort after all other possibilities (wiring, relay, connectors) have been exhaustively ruled out. If an internal module fault is confirmed (e.g., a shorted driver circuit for the relay), the module will need to be replaced. Be aware that control module replacement often requires programming or “flashing” the new module to the vehicle’s specific VIN and options, which typically requires specialized dealer-level diagnostic equipment.
• Post-Repair Verification: After completing any repair, clear the DTCs with the scan tool. Perform a functional test of the battery saver system by turning off the ignition, removing the key, and waiting for the specified time (or opening/closing a door as per system design) to ensure accessories power down correctly. Verify that all previously affected accessories now function as intended. Consider performing a parasitic draw test with an amp clamp after the vehicle has entered its sleep mode to confirm the absence of excessive current drain.