What Does B1873 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground in the power feed circuit that supplies voltage to the turn signal and hazard light system. The BCM monitors this circuit and sets this code when it detects abnormally low voltage or excessive current draw, indicating the power wire is making unwanted contact with ground. This prevents proper operation of turn signals and hazard lights.
Common Causes
45%
Damaged or chafed wiring in the turn signal/hazard power feed circuit, particularly at pinch points near steering column, under dash, or in door jambs
25%
Failed multifunction switch or turn signal stalk with internal short to ground
15%
Faulty hazard light switch with internal short circuit
10%
Water intrusion or corrosion in BCM connector causing short to ground on power output pin
5%
Failed Body Control Module with internal short on output driver circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of all turn signal and hazard wiring, particularly around steering column, under dash, and at all connectors. Look for damaged insulation, pinched wires, corrosion, or evidence of water intrusion.
2
Step 2: Disconnect the multifunction switch and hazard switch connectors. Using a digital multimeter, measure resistance between the turn signal power feed wire (at BCM connector) and chassis ground. Reading should be greater than 10k ohms. If reading is low (under 100 ohms), the short is in the wiring harness between BCM and switches.
3
Step 3: With switches still disconnected, reconnect BCM and command turn signals on using scan tool active tests or bi-directional controls. Measure voltage at disconnected switch connectors. Should read battery voltage (12-14V). If voltage is present and short code does not return, suspect faulty switch.
4
Step 4: If wiring tests good, reconnect multifunction switch only and test for short. Then reconnect hazard switch and test again to isolate which component is causing the short. Use multimeter in current measurement mode (10A setting) to verify normal current draw is under 5 amps total for all turn signal bulbs.
5
Step 5: Inspect BCM connector terminals for corrosion, pushed-back pins, or signs of overheating. Check BCM mounting area for water leaks or moisture accumulation that could cause connector corrosion.
6
Step 6: After repairs, clear codes, cycle turn signals and hazard lights through all functions, and road test vehicle. Re-scan to verify code does not return and monitor BCM data stream for normal voltage readings on turn signal circuit.
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground in the power feed circuit that supplies voltage to the turn signal and hazard light system. The BCM monitors this circuit and sets this code when it detects abnormally low voltage or excessive current draw, indicating t...
The most common cause of B1873 (Turn Signal / Hazard Power Feed Circuit Short To Ground) is: Damaged or chafed wiring in the turn signal/hazard power feed circuit, particularly at pinch points near steering column, under dash, or in door jambs
Typical repair costs for B1873 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is unsafe to drive as non-functioning turn signals and hazard lights eliminate the ability to signal lane changes and warn other drivers of your presence during emergencies. Repair immediately before operating on public roads to avoid accidents and traffic violations.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1873 to identify the root cause.
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Quick Info
Category
Body
System
Exterior Lighting System / Body Control
Difficulty
Type
Manufacturer
Recommended Tools
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