Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Scan Tool Data Definitions: Outputs
Backup Lamps: The scan tool displays the commanded state of the BCM which directly supplies battery positive voltage to the backup lamps. The scan tool displays On when the BCM activates the backup lamps upon receiving a backup lamp request signal from the powertrain control module (PCM).
Daytime Running Lamps: The scan tool displays the commanded state of the DRL. The scan tool displays On when the BCM signals the turn/hazard flasher module to illuminate the DRL.
Headlamps On Indicator: The scan tool displays the commanded state of the BCM which directly supplies battery positive voltage to the headlamps on indicator. The scan tool displays On when the BCM activates the headlamps on indicator upon receiving a headlamp request signal from the headlamp switch.
High Beams: The scan tool displays the commanded state of the high beam relay. The scan tool displays On when the BCM allows the high beam relay to go to ground activating the high beam headlamps.
Inadvertent Power: The scan tool displays the state of the inadvertent power battery rundown protection feature of the BCM. The scan tool displays Off when all inadvertent power circuits are functioning normally.
Low Beam Output: The scan tool displays the commanded state of the low beam relay. The scan tool displays On when the BCM allows the low beam relay to go to ground activating the high beam headlamps.
Park Lamp Relay: The scan tool displays the commanded state of the park lamp relay. The scan tool displays On when the BCM allows the park lamp relay to go to ground to activate the park lamps.
RAP Relay: The scan tool displays the commanded state of the retained accessory power (RAP) relay. The scan tool displays On when the BCM allows the relay to go to ground.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.