B1694
Autolamp On Circuit Open
Body Chassis/Safety Automatic Lighting 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The automatic headlight control circuit has an open connection, meaning power can't flow through the wiring or switch. It's like trying to turn on a light with a broken wire—the switch works but electricity never reaches the bulb.

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Symptoms You May Notice
3 known symptoms for this code
Automatic headlights do not turn on when ambient light sensor triggers them
Autolamp feature completely inactive or unavailable
Dashboard warning indicator for lighting system may appear
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage and current flow in the autolamp control circuit, expecting to see proper signal continuity when the automatic lighting function is enabled. An open circuit results in no voltage return or extremely high resistance, triggering the fault code.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Autolamp Circuit Voltage 12V with load draw present 0V or open circuit detected
Circuit Resistance <5 ohms >50 ohms or infinite resistance
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness connectors
Inspect all connectors in the autolamp circuit for corrosion, loose pins, or moisture and reseat them firmly.
2
Autolamp relay
Locate the relay in the fuse box and swap it with an identical relay to test for a failed relay.
3
Autolamp wiring
Trace the complete circuit from the light switch to the headlight module and repair or replace any damaged or corroded wire sections.