What Does B1875 Mean?
This code indicates the Body Control Module (BCM) has detected an abnormal signal or lack of communication from the turn signal and hazard switch assembly. The BCM monitors the switch circuit for proper voltage levels and continuity, and this fault means the expected signal patterns are not being received when the switch is operated. This affects the vehicle's ability to properly activate turn signals and hazard flashers through the body control system.
Common Causes
45%
Faulty turn signal/hazard switch assembly with internal electrical failure or worn contacts
30%
Open circuit, short to ground, or damaged wiring in the switch signal harness between switch and BCM
15%
Corroded or loose electrical connector at the turn signal switch or BCM connector pins
10%
Failed Body Control Module with internal circuit board damage affecting switch input processing
Diagnostic Steps
1
Step 1: Perform a visual inspection of the turn signal/hazard switch assembly for obvious damage, loose mounting, or signs of moisture intrusion. Check all associated connectors for corrosion, pushed-back pins, or damage.
2
Step 2: Using a digital multimeter, backprobe the turn signal switch connector while operating the switch through all positions. Verify voltage changes between 0V and battery voltage (typically 12V) at the signal wire as specified in vehicle wiring diagrams.
3
Step 3: Disconnect the turn signal switch connector and check for continuity and proper resistance values through the switch in each position (left, right, hazard) according to manufacturer specifications. Compare readings to known-good values.
4
Step 4: Inspect wiring harness from switch to BCM for chafing, pinching, or damage. Use multimeter to test continuity of each wire from switch connector to BCM connector with both ends disconnected. Resistance should be less than 1 ohm.
5
Step 5: Check BCM connector for corrosion and proper pin tension. With BCM connector disconnected and ignition off, measure resistance between BCM switch input pins and ground to check for shorts (should be open circuit/infinite resistance).
6
Step 6: If all wiring and connections test good, perform functional test with known-good turn signal switch assembly or clear codes and monitor live data while actuating the switch. If code returns with good switch, BCM replacement may be required.
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an abnormal signal or lack of communication from the turn signal and hazard switch assembly. The BCM monitors the switch circuit for proper voltage levels and continuity, and this fault means the expected signal patterns are not being re...
The most common cause of B1875 (Turn Signal / Hazard Switch Signal Circuit Failure) is: Faulty turn signal/hazard switch assembly with internal electrical failure or worn contacts
Typical repair costs for B1875 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is drivable but turn signals and hazard lights may not function properly, significantly reducing safety when changing lanes or signaling other drivers. Repair should be completed promptly to maintain legal compliance and prevent accidents due to inability to signal intentions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1875 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Lighting System
Difficulty
Type
Manufacturer
Recommended Tools
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