What does it mean?
B1624 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Lamp Keypad Output Open Circuit .
Symptoms
- The keypad does not light when touched or when the door handle is used at night, although the code entry itself still works
- Keypad backlighting works intermittently and cuts out as the door is moved
- No illumination on approach, making the keypad hard to use in the dark
- The code returns after every door cycle
- The rest of the door lighting and functions work normally
Likely causes
- Failed illumination LED or lamp inside the door mounted entry keypad
- Open wire between the module and the keypad, usually in the door hinge boot
- Corroded keypad connector after water has entered the door
- Keypad assembly failed internally
- Missing or corroded ground return for the keypad lamp
- Module output driver open internally
- Connector terminal backed out after door trim or speaker work
How to fix it
- Command the keypad lamp with the scan tool output test and watch the keypad, which shows immediately whether the module is trying to drive it
- Back-probe the output at the module and check for the expected voltage when the lamp is commanded
- Check continuity from the module pin to the keypad connector, flexing the hinge boot loom while measuring
- Inspect the keypad connector for water and corrosion behind the door trim, a common problem on this circuit
- Check the ground side of the keypad lamp with a voltage drop test
- Apply a fused supply and ground directly to the keypad lamp to prove the assembly before condemning it
- Replace the keypad assembly if it fails the direct supply test, and leave the module for last