B1313

Step 1: Locate the battery saver relay in the fuse/relay box (typically under hood or dash). Visually inspect the relay and its socket for signs of burning, corrosion, or damage. Remove relay and inspect socket terminals for corrosion or spread terminals.

Step 2: Using a digital multimeter, measure resistance across the relay coil terminals (typically pins 85 and 86). Normal reading should be 50-120 ohms. Reading of infinite resistance indicates open coil; zero resistance indicates short.

Step 3: Check relay control circuit fuse(s) in the power distribution center. If blown, investigate for short circuits before replacing. With relay removed and ignition on, measure voltage at relay socket control terminal from BCM (typically 12V present when BCM commands relay off).

Step 4: Inspect wiring harness between relay socket and BCM for chafing, pinching, or damage. Check connector at BCM for corrosion, backed-out pins, or moisture intrusion. Wiggle test harness while monitoring circuit continuity.

Step 5: If all wiring, fuses, and relay test good, suspect BCM internal relay driver failure. Verify BCM ground circuits are intact with less than 0.5 ohms resistance to chassis ground.

Step 6: After repairs, clear codes, cycle ignition off for 5 minutes, then restart vehicle. Monitor for code recurrence and verify all accessory loads operate normally after vehicle sits with ignition off.