B2699 on 2017 Chevrolet Silverado: Snowplow Headlight Circuit Fault Guide

What's Unique About the 2017-2017 Chevrolet SILVERADO

For the K2XX generation Silverado (2014-2019), this code is uniquely and strongly associated with aftermarket snowplow installations. The truck's BCM is very sensitive to the electrical load and timing of signals from third-party equipment. As explained in GM Upfitter Bulletin #116, the BCM performs a diagnostic check when the headlights are turned on; it expects to see a specific inrush of current that quickly settles. If a snowplow module switches power *after* this check, the BCM misinterprets the delayed current draw as a short circuit to ground and sets the code, disabling the circuit to protect the driver IC.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Right headlight is inoperative.
• Headlights (truck or plow) are flickering, especially when switching between them.
• Snowplow headlights are inoperative.
• A 'Service Headlamp System' message may appear on the driver information center.

Most Likely Causes

1. Faulty or Incompatible Snowplow Headlight Module/Wiring 🔴 High Probability As documented in GM TSBs PIT5412A, C, and D, the BCM in these trucks is highly sensitive to the electrical characteristics of aftermarket headlight switching modules used for snowplows. The BCM's self-protection feature is often triggered by the delayed or incorrect current draw from these modules.
   How to confirm: Disconnect the snowplow wiring harness from the truck completely. Clear the DTCs with a scan tool. Cycle the ignition and headlights. If code B2699 does not return, the fault is isolated to the snowplow's electrical system.
   Typical fix: Repair or replace the snowplow's headlight changeover module or wiring harness per the snowplow manufacturer's instructions. Plow manufacturers like Western, Fisher, and BOSS have released updated harnesses and modules to be compatible with this BCM logic. For example, Western/Fisher/SnowEx/Blizzard use harness kit 69818-2 for 2015-2019 GM trucks. BOSS issued Service Bulletin SV112 which advises turning the truck's headlights OFF before switching to plow lights as a procedural workaround.
   Est. part cost: $50-$350
2. Open or Short in Headlight Wiring Harness ⚪ Low Probability This is a possible cause if a snowplow is not and has never been installed. Connectors and wiring are exposed to the elements and can become damaged or corroded over time.
   How to confirm: With the vehicle off, disconnect the BCM and the right headlight. Use a multimeter to check for continuity (to find an open) and resistance to ground/power (to find a short) on the control circuit wire between the two points.
   Typical fix: Locate and repair the damaged section of the wiring harness or replace a corroded connector pigtail.
   Est. part cost: $20-$100

Rare But Worth Checking

• Faulty Body Control Module (BCM): This should only be considered after all external wiring, bulbs, and aftermarket equipment (especially snowplow systems) have been definitively ruled out. Unnecessary BCM replacement is a common and expensive misdiagnosis for this code. If replacement is necessary, a common part number is 13595583, but it requires dealer programming.

Diagnosis Steps

1. Scan the Body Control Module (BCM) for codes. Confirm B2699 is present and note any other codes, such as B2575.
2. Verify if the truck is equipped with a snowplow or has had one in the past. If so, the fault is almost certainly related to the upfitter's wiring.
3. Disconnect the entire snowplow wiring harness from the vehicle. This is the most critical step.
4. Clear all DTCs using a professional scan tool.
5. Cycle the ignition and operate the headlights normally. If the code does not return, the problem is confirmed to be within the snowplow's electrical system.
6. If the code returns with the plow harness disconnected, proceed to diagnose the truck's factory wiring. Inspect the harness to the right headlight for any signs of damage, corrosion, or previous modification.
7. Test the circuit for shorts or opens using a multimeter.
8. If the snowplow system is the cause, contact the snowplow manufacturer for their recommended updated wiring harness or module. Reference GM Upfitter Integration Bulletin #116 for technical details. For BOSS plows, a temporary workaround is to turn the truck's headlight switch to OFF before changing between truck and plow lights.

Parts You'll Likely Need

• Snowplow Headlight Harness/Module Kit (OEM #Western/Fisher/SnowEx/Blizzard: 69818-2; BOSS: MSC09142; 🎬 See this walkthrough for installing Boss truck-side plow wiring. Western/Fisher 3-Port Isolation Module: 29070-1) 🎬 Watch: Training on how the Western isolation module circuit works. — This is the most common fix. The original module or wiring from the snowplow manufacturer is incompatible with the 2017 Silverado's BCM logic. An updated kit is required.
  Trusted brands: Western, Fisher, Boss, SnowEx
  OEM price range: $150-$350
  Aftermarket price range: $150-$350
• Body Control Module (BCM) (OEM #13595583, 13528945) — This is a very rare cause and should only be replaced as a last resort after all other possibilities are exhausted. Requires dealer programming.
  Trusted brands: ACDelco
  OEM price range: $300-$500
  Aftermarket price range: $200-$400

Related Codes That Often Appear With This One

• B2575 — This is the corresponding code for the left headlamp control circuit. According to GM TSBs PIT5412A, C, and D, these two codes are frequently set together when a snowplow installation is the root cause.

Technical Service Bulletins (TSBs) & Recalls

• PIT5412D: Headlight Flicker or Inoperative When Switching Between The Truck and Snow Plow Headlights.
• PIT5412C: Superseded by PIT5412D, addresses the same snowplow headlight issue.
• PIT5412A: An earlier version of the TSB, also addressing inoperative snowplow headlamps and codes B2575/B2699.
• BOSS Service Bulletin SV112: Provides a workaround for their plows, instructing users to turn the truck's main headlight switch to OFF before operating the plow's light switch to prevent the fault.

Platform-Specific Known Issues

• GM Technical Service Bulletin PIT5412D explicitly states that flickering or inoperative headlights with codes B2699 and B2575 on trucks with snowplows is an issue with the snowplow manufacturer's headlight changeover system, not the truck itself.
• GM Upfitter Bulletin #116 provides the technical explanation: the BCM performs a diagnostic check at startup. If an aftermarket module switches to plow lights *after* this check, the BCM sees the delayed current inrush as a short-to-ground and disables the circuit for protection.

Hidden / Shadow Codes Worth Checking

• B2699 01: Right Headlamp Control Circuit Short to Voltage. The BCM has detected that the control circuit is shorted to a power source. (see via Requires a professional GM-specific scan tool like a GDS2 or high-end equivalent to view symptom bytes.)
• B2699 02: Right Headlamp Control Circuit Short to Ground. The BCM has detected that the control circuit is shorted to ground. This is the most common variant seen with incompatible snowplow modules. (see via Requires a professional GM-specific scan tool like a GDS2 or high-end equivalent to view symptom bytes.)
• B2699 04: Right Headlamp Control Circuit Open. The BCM has detected a break in the circuit, which could be a disconnected connector, broken wire, or a simple burned-out bulb. (see via Requires a professional GM-specific scan tool like a GDS2 or high-end equivalent to view symptom bytes.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Body Control Module > Exterior Lighting > Headlamp Control — After disconnecting any aftermarket equipment, a technician can use this bidirectional command to force the right headlight 'Active' and 'Inactive'. If the headlight turns on and off with this command but not with the physical switch, it helps isolate the fault to the switch or input side of the BCM. If it fails to activate, it confirms a fault in the BCM output driver or the wiring to the headlamp.

Wiring & Ground Locations

• G105 — Located at the left front of the engine compartment, behind the cooling fan relays.. This is the primary grounding point for the Right Front (RF) Low & High Beam Headlamps. A loose or corroded connection at this specific ground can cause high resistance, leading to a dim or inoperative right headlight and potentially setting a B2699 code, even if all other wiring appears correct.
• BCM (Body Control Module) — Located on the lower left side of the dashboard, accessible by removing the driver's side knee bolster panel.. This is the module that controls the headlight circuit and sets the code. All circuit tests for the control wire will originate or terminate at one of the BCM's multi-pin connectors.

"I Checked Everything" — The Actual Cause

• In the context of this electrical code, the equivalent of a 'smoke test clean' scenario is when a technician tests the headlight control wire with a multimeter and finds no direct short-to-ground or open circuit. The wiring appears perfect. However, the code still sets because the BCM is not just checking for basic faults; it's monitoring the *timing and characteristics* of the current draw. An incompatible snowplow module can pass a simple resistance test but will draw current too slowly after the BCM's initial diagnostic check, causing the BCM to incorrectly flag it as a fault and shut down the circuit for protection. This is why simply disconnecting the plow harness is the definitive test.

OEM Part Supersession History

• 13595583 → 13528945 (related part, not a direct supersession) — These part numbers are often listed together for the same applications.
  Heads up: These BCMs are not plug-and-play. Replacing the BCM requires either programming by a GM dealer using the SPS (Service Programming System) or sending the original module to a specialist service to have its data cloned onto the replacement unit. Failure to do so will result in a no-start condition or malfunctioning vehicle features.