Code
B1624
Other
B — Body
Lamp Keypad Output Open Circuit
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between module and keypad lamp
- Poor or corroded connector at lamp or module
- Failed keypad lamp/LED or lamp assembly
- Blown fuse supplying the lamp circuit
- Disconnected lamp socket or mechanical damage
- Failed body control module (less common)
Symptoms
- Keypad or keypad backlight does not illuminate
- Inconsistent or intermittent keypad lamp operation
- Related body module lamp fault lamp or stored codes
- Possible loss of keypad illumination only when other lamps work
What to check
- Retrieve and record freeze frame and related lamp codes with a scan tool
- Visually inspect keypad, lamp assembly and harness for damage, corrosion or disconnected connectors
- Check fuses for the keypad/backlight circuit
- Wiggle harnesses/connectors while observing keypad operation for intermittent faults
- Measure continuity between BCM/module lamp output pin and the lamp connector (with ignition off)
- Measure voltage at the module output and at the lamp connector with ignition or lighting circuit active
Signal parameters
- Expected open-circuit fault condition: continuity interrupted between module output and lamp
- Expected voltage with output ON: approximately battery voltage (~11–13.5 V) at lamp connector (may be PWM on some vehicles)
- Expected voltage with output OFF: ~0 V at module lamp output
- Expected lamp load current: typically low (tens mA for LED, up to 0.5–2 A for incandescent bulbs) — refer to vehicle-specific specs
Diagnostic algorithm
- Connect a scan tool, confirm B1624 and note related codes; clear codes and attempt to reproduce.
- Visually inspect keypad lamp assembly, socket and wiring for damage, corroded terminals or separation; inspect fuses protecting the circuit.
- With ignition off, disconnect the keypad connector and check continuity between the module output pin and the keypad lamp terminal. If no continuity, isolate wiring and repair open section.
- Inspect and test the lamp/LED itself: measure resistance or apply known good 12 V briefly to verify operation. Replace lamp assembly if LED/bulb is open.
- With ignition on, backprobe the module output and lamp connector: verify voltage on output when lamp should be ON. If module output shows correct voltage but lamp doesn’t light, suspect lamp/connector. If output shows no voltage, suspect wiring or module.
- If wiring and lamp test good but output remains open, inspect module grounds and related power supplies; repair any poor ground or supply issues.
- After repair, clear codes and re-check operation under normal conditions to confirm the fault is resolved.
Likely causes
- Broken wire or pinched harness at door hinge or dash area
- Corroded or pushed-out connector at the keypad or BCM
- Failed LED element inside the keypad (open LED)
- Blown fuse protecting the keypad lighting circuit
Fault status
Status
Lamp Keypad Output Open Circuit — the keypad lamp output circuit is open or not providing expected continuity/load to the lamp.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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