What Does B1386 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground in the oil level warning lamp circuit. The BCM continuously monitors the lamp circuit for proper resistance and voltage, and has determined that the circuit voltage is being pulled to ground when it should not be. This prevents the oil level warning lamp from functioning correctly and may cause it to illuminate continuously or behave erratically.
Common Causes
45%
Damaged or chafed wiring harness between BCM and oil level lamp causing short to ground
30%
Failed instrument cluster with internal short in oil level lamp circuit
15%
Faulty BCM with internal short on lamp driver circuit
10%
Corroded or damaged connector terminals at BCM or instrument cluster causing intermittent ground
Diagnostic Steps
1
Step 1: Perform visual inspection of instrument cluster and BCM connectors for corrosion, bent pins, or moisture intrusion. Disconnect both connectors and inspect terminals for damage.
2
Step 2: Using a digital multimeter, measure resistance between the oil level lamp circuit wire at the BCM connector (harness side) and known good ground. Reading should be infinite (open circuit); low resistance confirms short to ground in harness or cluster.
3
Step 3: Disconnect instrument cluster connector and retest resistance from BCM side lamp circuit to ground. If resistance is now infinite, the short is internal to the instrument cluster. If still low resistance, short is in the wiring harness.
4
Step 4: Inspect wiring harness routing between BCM and instrument cluster, paying special attention to areas where harness contacts metal body panels, passes through grommets, or near moving components. Look for damaged insulation or pinched wires.
5
Step 5: If harness tests good, reconnect harness and use BCM scan tool functions to command oil level lamp on/off while monitoring voltage at the lamp circuit. Inability to control lamp with good wiring indicates faulty BCM or instrument cluster.
6
Step 6: Repair identified fault (replace damaged harness section, repair connector, or replace instrument cluster/BCM as needed), clear codes, and verify oil level lamp operates correctly through BCM actuator tests.
Estimated Repair Cost
$100 - $650
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground in the oil level warning lamp circuit. The BCM continuously monitors the lamp circuit for proper resistance and voltage, and has determined that the circuit voltage is being pulled to ground when it should not be. This ...
The most common cause of B1386 (Oil Level Lamp Circuit Short To Ground) is: Damaged or chafed wiring harness between BCM and oil level lamp causing short to ground
Typical repair costs for B1386 range from $100 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects the warning lamp circuit, not actual oil level monitoring. However, repair promptly as you will not receive oil level warnings if the actual oil level becomes low, which could lead to engine damage if oil levels are not manually checked regularly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1386 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Instrument Cluster
Difficulty
Type
Manufacturer
Recommended Tools
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