What Does B1371 Mean?
This code indicates the Body Control Module (BCM) has detected a fault in the illuminated entry relay circuit, which controls interior courtesy lighting when doors are opened or the vehicle is unlocked. The BCM monitors the relay coil circuit for opens, shorts, or excessive resistance that prevent proper relay operation. This affects the convenience lighting system that illuminates the cabin for entry/exit.
Common Causes
35%
Faulty illuminated entry relay with internal coil failure or damaged contacts
30%
Corroded or loose relay socket connections in the fuse/relay box
20%
Damaged wiring or broken conductors between BCM and illuminated entry relay
15%
Failed BCM relay driver circuit or internal short within BCM module
Diagnostic Steps
1
Step 1: Locate the illuminated entry relay in the fuse/relay panel and perform a visual inspection for corrosion, burnt terminals, or physical damage to relay and socket. Remove relay and inspect socket pins for discoloration or looseness.
2
Step 2: Using a multimeter, test the relay coil resistance (typically 70-90 ohms between coil terminals) and contact continuity. Check for proper relay operation by applying 12V to coil terminals while monitoring contact closure with ohmmeter.
3
Step 3: With relay removed and ignition on, use multimeter to verify BCM is providing proper ground signal to relay control circuit when entry lighting should activate (door open or unlock command). Backprobe BCM connector if necessary to verify output signal.
4
Step 4: Inspect wiring harness between BCM and relay socket for chafing, cuts, or pinched wires. Perform continuity test on relay control circuit from BCM connector to relay socket, checking for opens or shorts to ground/power.
5
Step 5: If all wiring and relay test good, suspect BCM internal relay driver failure. Verify all BCM grounds are clean and tight. Replace BCM if internal driver circuit is confirmed failed.
6
Step 6: After repairs, clear codes and perform functional test by cycling door locks and opening doors to verify proper illuminated entry operation. Monitor for code recurrence.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a fault in the illuminated entry relay circuit, which controls interior courtesy lighting when doors are opened or the vehicle is unlocked. The BCM monitors the relay coil circuit for opens, shorts, or excessive resistance that prevent p...
The most common cause of B1371 (Illuminated Entry Relay Circuit Failure) is: Faulty illuminated entry relay with internal coil failure or damaged contacts
Typical repair costs for B1371 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is safe to drive as it only affects convenience lighting for vehicle entry. No immediate safety concern exists, though reduced cabin illumination at night may be a minor inconvenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1371 to identify the root cause.
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Quick Info
Category
Body
System
Body/Interior Lighting Control System
Difficulty
Type
Manufacturer
Recommended Tools
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