B1333
Decklid Ajar Rear Door Circuit Short To Battery
Body Chassis/Safety Door/Latch Control 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The decklid (trunk) ajar sensor circuit is shorted directly to the battery voltage, making the ECU think the trunk is always sending a high signal. This is like a light switch stuck in the ON position, continuously sending full power instead of switching between states.

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Symptoms You May Notice
3 known symptoms for this code
Decklid ajar warning light stays on continuously
Trunk/liftgate won't lock or unlock properly
Dashboard message displays trunk open when it's actually closed
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the decklid ajar switch circuit voltage, expecting it to toggle between ground (closed) and battery voltage (open). A short to battery means the voltage remains constantly high, indicating an open circuit fault. The ECU detects this abnormal high-voltage condition that never transitions low.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Decklid Switch Voltage 0V (closed) to 12V (open) with transitions Constant 12V+ with no state change
Circuit Resistance High impedance when open, near 0Ω when closed Direct battery connection bypassing switch
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Decklid ajar switch connector
Inspect and reseat the connector at the trunk latch; corrosion or loose pins can cause false shorts.
2
Decklid ajar switch wiring harness
Check for pinched, abraded, or damaged wires between the trunk latch and body that may be shorted to battery positive.
3
Decklid ajar switch assembly
Replace the switch if wiring checks out; internal switch failure can cause permanent high voltage output.