What Does B1508 Mean?
This code indicates that the Body Control Module (BCM) has detected an open circuit in the flash-to-pass switch wiring or the switch itself. The flash-to-pass feature allows drivers to briefly activate high beams by pulling the turn signal stalk without latching them on. The BCM monitors this switch circuit and sets this code when it cannot detect continuity or proper voltage signals from the switch input.
Common Causes
45%
Failed or damaged flash-to-pass switch contacts within the multifunction turn signal stalk assembly
30%
Broken or corroded wiring between the BCM and multifunction switch connector
15%
Loose or corroded connector at the multifunction switch or BCM
10%
Failed Body Control Module with internal circuit fault
Diagnostic Steps
1
Step 1: Perform a visual inspection of the multifunction switch connector under the steering column. Check for loose connections, bent pins, corrosion, or moisture. Disconnect and reconnect the connector to ensure proper seating.
2
Step 2: Using a digital multimeter, backprobe the flash-to-pass switch signal wire at the multifunction switch connector while operating the stalk. Verify voltage changes between 0V and battery voltage (typically 12V) when activating the flash-to-pass function. Consult wiring diagram for proper pin identification.
3
Step 3: Check continuity of the signal wire from the multifunction switch connector to the BCM connector with the harness disconnected at both ends. Resistance should be less than 5 ohms. Also verify ground circuit continuity with less than 1 ohm resistance.
4
Step 4: If wiring tests pass, remove and bench test the multifunction switch assembly by applying voltage and measuring switch output with an ohmmeter while cycling the flash-to-pass function. Replace switch if it fails to show proper open/closed states.
5
Step 5: Clear the code and perform a functional test of the flash-to-pass feature. Monitor live data for switch status changes while operating the control to verify proper BCM recognition and repair success.
Estimated Repair Cost
$120 - $450
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an open circuit in the flash-to-pass switch wiring or the switch itself. The flash-to-pass feature allows drivers to briefly activate high beams by pulling the turn signal stalk without latching them on. The BCM monitors this switch...
The most common cause of B1508 (Flash To Pass Switch Circuit Open) is: Failed or damaged flash-to-pass switch contacts within the multifunction turn signal stalk assembly
Typical repair costs for B1508 range from $120 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is safe to continue driving as it only affects the flash-to-pass convenience feature. The headlights will still function normally in their standard low and high beam positions. Repair at your convenience, though the feature is useful for signaling other drivers.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1508 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System
Difficulty
Type
Manufacturer
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