B1338
Door Ajar RR Circuit Short To Ground
Body Chassis/Safety Door sensors 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The rear right door ajar sensor circuit is shorted to ground, meaning the electrical signal wire is touching the metal chassis instead of properly communicating the door position. It's like a light switch stuck in the 'on' position because the wire got pinched.

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Symptoms You May Notice
3 known symptoms for this code
Door ajar warning light stays illuminated on dashboard
Interior dome light remains on continuously
Vehicle may not lock doors or triggers false alarm warnings
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the voltage signal from the rear right door ajar switch, expecting a high voltage when the door is closed and low voltage when open. A short to ground forces the signal to zero volts constantly, causing the ECU to think the door is always in an abnormal state.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Door Ajar Switch Signal Voltage High (4.5-5.5V) when closed, Low (0.5V) when open Continuous 0V (shorted to ground)
Circuit Resistance 500-1000 ohms normal, infinite when open Less than 50 ohms (direct short)
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Door ajar switch connector
Inspect the RR door jamb switch connector for corrosion, moisture, or loose pins and reseat or clean the connection.
2
Door ajar switch wiring harness
Check the wiring between the door and frame for pinches, cuts, or abrasion where insulation is compromised.
3
Door ajar switch assembly
Replace the rear right door jamb switch if corrosion or internal failure is confirmed.