B1507

Code

Other B — Body

Flash To Pass Switch Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 27 EN: 37 RU: 32

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Page language: EN

Causes

Open circuit in flash‑to‑pass switch wiring (broken wire, chafing)
Short to ground or short to power in switch circuit
Poor connector contact or corrosion at switch or BCM connector
Faulty flash‑to‑pass switch (mechanical/electrical failure)
Blown fuse or poor power/ground to the switch circuit
Faulty BCM or internal input circuit failure

Symptoms

Flash‑to‑pass (momentary high beam flash) does not operate
Intermittent operation of the flash‑to‑pass function
High‑beam indicator may not flash when using the switch
DTC B1507 stored and/or BCM warning or message present
Possible other lighting circuit anomalies if wiring is shared

What to check

Scan for stored codes and freeze frame data; note test I/O or status data for the flash‑to‑pass input
Verify operation of the high beams and flash‑to‑pass while monitoring with a scan tool or voltmeter
Visually inspect the flash‑to‑pass stalk/switch and its connector for corrosion, bent pins or water intrusion
Check fuses and fusible links related to the lighting and BCM circuits
Wiggle the steering column and switch while observing function to reproduce intermittent faults
Backprobe the switch connector to observe signal when the switch is used

Signal parameters

Supply voltage to switch: approximately battery voltage (~12 V) with ignition ON
Switch closed (depending on design): expected continuity near 0–2 ohms between switch terminal and return/ground or switch output
Open switch: infinite resistance between switched terminals
Signal to BCM: either a switched ground or switched 12 V; when actuated expect a change from ~0 V to ~9–12 V or from ~12 V to ~0 V depending on vehicle design
Input circuit current: typically low (

Diagnostic algorithm

Verify and record the code with a scan tool; clear the code and attempt to re‑create to confirm repeatability
Check relevant fuses and power/ground circuits for the switch using a DMM
Inspect the switch and connector visually; repair any corrosion, bent pins or damage
Backprobe the switch connector and operate the flash‑to‑pass while observing voltage behavior at the supply and output pins. Compare with expected signal parameters
Check continuity between the switch output and the BCM input; with harness disconnected, measure resistance to rule out open circuits
If intermittent, wiggle test the wiring harness and switch while monitoring the signal for breaks or shorts
If wiring and connector check good and the switch does not present correct signal, replace the flash‑to‑pass switch assembly
If a known good switch still shows incorrect input at the BCM, test or swap the BCM input circuit if possible, or consult manufacturer repair information — module replacement or reprogramming may be required
After repair, clear codes and road test; re‑scan to confirm the code does not return

Likely causes

Faulty or worn flash‑to‑pass switch
Open or intermittent wiring between switch and BCM
Corroded/loose connector at the switch or BCM
Short to ground on the switch output

Fault status

⚠️ Status

B1507 — Flash To Pass Switch Circuit Failure: BCM detected abnormal voltage/continuity in the flash‑to‑pass switch circuit. Check switch, wiring, connectors, fuses and BCM inputs.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours