What Does B1570 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground condition in the high-beam headlamp circuit. When the high-beam switch is activated, the BCM monitors circuit resistance and current flow, and has identified an abnormally low resistance path to ground, causing excessive current draw. This prevents proper high-beam operation and may blow fuses or damage the BCM output driver.
Common Causes
45%
Damaged, chafed, or pinched wiring in the high-beam circuit creating a direct ground path, typically in areas where wiring harness flexes or passes through metal body panels
30%
Failed high-beam headlamp bulb with internal short to ground or corroded bulb socket allowing ground contact
15%
Water intrusion or corrosion in headlamp housing causing short circuit between power and ground circuits
10%
Faulty headlamp relay or BCM high-beam output driver with internal short to ground
Diagnostic Steps
1
Step 1: Perform visual inspection of both high-beam headlamp bulbs, sockets, and connectors for signs of water intrusion, corrosion, melted terminals, or physical damage. Remove bulbs and inspect for blackened or shorted filaments
2
Step 2: Disconnect both high-beam bulb connectors and measure resistance from the high-beam power wire (at BCM side of connector) to chassis ground using a digital multimeter. Reading should be greater than 10k ohms; less than 100 ohms confirms short to ground
3
Step 3: If short persists with bulbs disconnected, disconnect headlamp relay (if equipped) and BCM connector for high-beam circuit. Measure resistance from BCM high-beam output pin to ground. If reading is now normal (high resistance), fault is between BCM and bulb connector; if still shorted, fault is in BCM
4
Step 4: Visually trace and physically manipulate high-beam wiring harness from BCM to headlamps, checking for chafed insulation, pinch points at body panels, and damaged wire ties. Pay special attention to areas near engine bay, wheel wells, and front bumper mounting points
5
Step 5: After identifying and repairing the short circuit (wire repair, bulb replacement, or connector cleaning), reconnect all components and verify resistance readings are within specification (typically greater than 10k ohms to ground)
6
Step 6: Clear the diagnostic code, cycle the high-beam switch multiple times while monitoring live data for proper voltage and current readings, then test drive to confirm high-beams function correctly and code does not return
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground condition in the high-beam headlamp circuit. When the high-beam switch is activated, the BCM monitors circuit resistance and current flow, and has identified an abnormally low resistance path to ground, causing excessiv...
The most common cause of B1570 (Lamp Headlamp High-Beam Circuit Short To Ground) is: Damaged, chafed, or pinched wiring in the high-beam circuit creating a direct ground path, typically in areas where wiring harness flexes or passes through metal body panels
Typical repair costs for B1570 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive during daylight hours, but nighttime driving safety is significantly compromised without functioning high-beams, especially on unlit rural roads. Repair should be completed before extensive nighttime driving, and blown fuses should be replaced only after the short circuit is repaired to prevent BCM damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1570 to identify the root cause.
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Category
Body
System
Exterior Lighting System
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