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
All Door Unlock Relay: Display value will be On/Off. This output displays the state of the door unlock relay. It is normally Off, and pulses to On when activated. Unlocks all doors on vehicles without RFA. Unlocks passenger doors on vehicles with RFA.
Battery Voltage: The scan tool displays volts. The state of the battery voltage supplied to the body control module.
Door Lock Relay: Display value will be On/Off. This output displays the state of the door lock relay. It is normally Off, and pulses to On when activated.
Door Lock Switch: Display value will range from 0-4 volts. Normal values are 1.7V/3.4V/0.0V 10%. 1.7V=Unlock, 3.4V=Idle, 0.0V=Lock. These values are approximate and will increase or decrease depending on battery voltage.
Door Lock Switch: Display value will be Unlock/Idle/Lock. This input displays the state of the door lock switch. It is normally idle, and changes to Unlock or Lock corresponding to the voltage read by the BCM.
Driver Door Ajar Sw.: Display value will be On/Off.
On is displayed when the driver door is open, Off when closed.
Driver Door Unlock Relay: Display value will be On/Off. This output displays the state of the driver door unlock relay. It is normally Off, and pulses to On when activated. Not applicable to vehicles without RFA.
Last 4 Dig of GM Part No.: The scan tool displays the last 4 digits of the GM part number of the body control module that is currently in the vehicle.
Passenger Door Ajar Sw.: Display value will be On/Off. On is displayed when at least one passenger door is open, Off when all passenger doors are closed.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.