B1400

Step 1: Perform visual inspection of driver door wiring harness, particularly where it flexes between door and body pillar. Look for chafed, pinched, or damaged insulation that could cause short to battery voltage. Check for signs of previous repairs or aftermarket installations.

Step 2: Disconnect the one-touch window relay and use a digital multimeter to measure voltage at the relay control terminal from the BCM. Key on, engine off - should read 0 volts or system voltage only when window button is activated. If battery voltage is present continuously, trace wiring back toward BCM for short.

Step 3: Test the relay itself by checking resistance between control coil terminals (should be 50-200 ohms typically) and verify no continuity exists between control circuit and power circuit terminals. Replace relay if internal short is detected.

Step 4: Disconnect driver window switch and measure voltage at the relay control wire terminal in the switch connector. If battery voltage disappears, switch assembly is faulty. If voltage remains, fault is in wiring between switch and relay.

Step 5: Inspect BCM connector terminals for corrosion, water intrusion, or bent pins that may cause adjacent circuits to cross-connect. Clean and repair connector as needed.

Step 6: After repairs, clear codes, cycle window function through full up/down operations including one-touch feature, and verify code does not return. Test in both key-on and retained accessory power modes.