B1623

Lamp Keypad Output Circuit Failure

Body Chassis/Safety Lighting Control 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The vehicle's lamp keypad output circuit isn't working properly, similar to a light switch that won't send power to the bulb. This means the control module can't communicate with or power the lamp control buttons on your dashboard.

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Symptoms You May Notice

3 known symptoms for this code
Dashboard lamp control buttons unresponsive or non-functional
Interior lights won't dim or brighten when using keypad controls
Warning lights on dashboard related to lighting system
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the output voltage and current draw from the lamp keypad circuit to ensure proper communication and power delivery to the lamp control module. It checks for open circuits, shorts, and excessive resistance that would indicate a failure in the wiring or button assembly.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Output Voltage 12V nominal with proper modulation Below 10V or above 14.5V consistently
Circuit Resistance Below 10 ohms per connection Above 25 ohms indicating open or corroded circuit
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Lamp keypad connector
Disconnect and reconnect the lamp control module connector behind the dashboard, cleaning contacts with electrical contact cleaner.
2
Wiring harness
Inspect lamp keypad wiring for breaks, pinches, or corrosion; repair or replace damaged sections.
3
Lamp keypad assembly
Replace the entire keypad unit if contacts are worn or buttons are mechanically broken.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1623 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code B1623

What happens after you fix the fault

Once the fault is repaired, B1623 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.