B2699 on 2014-2016 GMC Sierra 1500: Right Headlight Circuit Fault Causes and Fixes

What's Unique About the 2014-2016 Gmc SIERRA 1500

For the 2014-2016 K2XX generation of GMC Sierra and its platform-mate, the Chevrolet Silverado, this code is uniquely and strongly associated with aftermarket snowplow installations. General Motors has issued multiple Technical Service Bulletins (TSBs) stating that when B2699 appears, especially with its left-side counterpart B2575, the root cause is almost always an issue with the snowplow's headlight changeover module. The truck's BCM is sensitive to the electrical load and timing of signals from this aftermarket equipment, often leading to these specific codes. GM explicitly states in TSBs like PIT5412D that this is not a fault with the truck's system but with the upfitter's equipment.

Diagnostic Flowchart

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

Symptoms You May Notice

• The right low-beam headlight does not turn on.
• The right low-beam headlight stays on continuously and will not turn off.
• Headlights (truck or plow) flicker or are inoperative when switching between the factory and snowplow lights.
• A 'Service Headlamp System' message may appear on the driver information center.
• The fault occurs immediately after switching from truck headlights to plow headlights.

Most Likely Causes

1. Faulty or Incompatible Snowplow Headlight Module/Wiring 🔴 High Probability As documented in GM TSBs PIT5412D, PIT5412C, and PIT5412A, the BCM in these trucks is sensitive to the electrical characteristics of aftermarket headlight switching modules used for snowplows. GM Upfitter Bulletin #116 explains the BCM's self-protection feature is triggered by the delayed current draw from these modules.
   How to confirm: Check if a snowplow lighting harness is installed. The issue will typically occur when switching between the truck and plow headlights. Consult the snowplow manufacturer for updated modules or wiring diagrams. The BOSS plow service bulletin SV112 suggests turning truck headlights OFF before switching to plow lights as a temporary workaround.
   Typical fix: Replace the snowplow's headlight changeover module with an updated version from the plow manufacturer or repair the plow's wiring harness per their instructions. For Western, Fisher, SnowEx, and Blizzard plows, the harness kit 69818-2 is specified for 2014-2015 GM 1500 trucks to resolve this. This kit often includes an updated isolation module.
   Est. part cost: $50-$350
2. Open or Short in Headlight Wiring Harness 🟡 Medium Probability
   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.
   Typical fix: Locate the damaged section of the wiring harness and repair or replace it. Pay close attention to the connector at the headlight assembly for corrosion or damage.
   Est. part cost: $5-$50 for wiring repair supplies
3. Burnt-Out Right Low-Beam Headlight Bulb ⚪ Low Probability
   How to confirm: Visually inspect the headlight bulb's filament. Swap the right low-beam bulb with the left one to see if the problem moves to the other side. The standard 🎬 Watch: Troubleshooting steps for headlights that won't turn on bulb type for these trucks is a 9012 (also called HIR2).
   Typical fix: Replace the right low-beam headlight bulb (type 9012).
   Est. part cost: $20-$100 depending on bulb type (Halogen vs. HID/LED)

Rare But Worth Checking

• Faulty Body Control Module (BCM): This is a rare cause. The BCM should only be suspected after all wiring, the bulb, and any aftermarket modules have been thoroughly tested and ruled out. BCM replacement requires programming by a dealer or qualified shop.
• Aftermarket LED or HID Headlight Bulbs: Installing aftermarket LED or HID bulbs without the proper CANbus decoders or anti-flicker harnesses can introduce unexpected electrical loads, potentially confusing the BCM and setting circuit fault codes like B2699. The BCM is designed for the specific inrush current of a halogen bulb.

Diagnosis Steps

1. Check for the presence of an aftermarket snowplow wiring harness. If installed, this is the primary area of suspicion.
2. If a snowplow harness is present, consult GM Upfitter Integration Bulletin #116 and contact the snowplow manufacturer for diagnostic advice, as recommended by GM TSB PIT5412D. The bulletin explains the BCM's sensitivity to delayed current draw.
3. As a test, follow the procedure in BOSS Service Bulletin SV112: turn the truck's main headlight switch to OFF before using the plow's rocker switch to change between truck and plow lights. If this prevents the code, it confirms the issue is with the plow module's switching behavior.
4. If no snowplow equipment is installed, begin by visually inspecting the right headlight bulb (type 9012) and its electrical connector for damage, corrosion, or loose pins.
5. Use a scan tool to read the specific fault type (e.g., short to ground, open circuit) to narrow down the search.
🎬 Watch: How to find and check your headlight fuses
6. If the bulb is good, test the headlight circuit. Disconnect the harness from the BCM and the headlight. Use a digital multimeter to check the control wire for continuity to rule out an open circuit.
7. Check the same wire for a short to ground (continuity between the wire and a chassis ground) and a short to voltage (check for voltage on the wire with the key on).
8. If all wiring and the bulb test normal, the fault may lie within the Body Control Module (BCM) itself, but this is highly unlikely.

Parts You'll Likely Need

• Snowplow Headlight Harness/Module Kit (OEM #Western/Fisher/SnowEx/Blizzard Kit P/N: 69818-2) — This is the most common cause of B2699 on these trucks. This specific kit is designed for the 2014-2015 GM 1500 to properly integrate with the sensitive BCM.
  Trusted brands: Boss, Fisher, Western, SnowEx
  OEM price range: $250-$350
  Aftermarket price range: $250-$350
• Low Beam Headlight Bulb (OEM #9012 (HIR2)) — A burnt-out bulb can cause an open circuit fault. It's a simple and common wear item, though less likely to be the root cause than plow issues on this truck.
  Trusted brands: ACDelco, Sylvania, Philips
  OEM price range: $40-$100
  Aftermarket price range: $20-$60
• Body Control Module (BCM) — This is the last resort if all wiring, bulbs, and aftermarket modules are confirmed to be working correctly. The BCM is the computer that controls the headlights.
  Trusted brands: ACDelco (OEM)
  OEM price range: $250-$400

Related Codes That Often Appear With This One

• B2575 — B2575 is the identical fault code for the Left Headlamp Control Circuit. They often appear together because snowplow lighting modules control both headlights and a fault in the module or its installation will affect both circuits simultaneously.

Technical Service Bulletins (TSBs) & Recalls

• PIT5412D: Headlight Flicker or Inoperative When Switching Between The Truck and Snow Plow Headlights. States this is not a truck issue and to contact the upfitter.
• PIT5412C: Superseded by PIT5412D, but contains the same essential information regarding snowplow headlight issues causing B2699/B2575.
• PIT5412B: An earlier version also pointing to the snowplow module as the cause.
• PIT5412A: An earlier version of the bulletin also pointing to snowplow headlamp integration issues and referencing GM Upfitter bulletin 116.
• GM Upfitter Bulletin #116: The core technical document explaining how the headlamp circuits on 2014+ GM trucks work and the specific requirements for aftermarket equipment (like plows) to avoid setting fault codes

Platform-Specific Known Issues

• GM Technical Service Bulletin PIT5412D explicitly notes that flickering or inoperative headlights with codes B2699 and B2575 on trucks with snowplows is not an issue with the truck's system, but with the snowplow manufacturer's headlight changeover module.
• GM Upfitter Bulletin #116 explains the technical reason for the fault: the BCM performs a diagnostic check upon commanding the low beams on. If an aftermarket module switches from the truck lights to the plow lights *after* this check, the BCM sees the new current inrush as a short-to-ground and disables the circuit for protection.

Mechanic-Grade Diagnostic Values

• Right Headlight Ground Circuit Resistance — expected: Less than 5 ohms. Failure: A reading greater than 5 ohms indicates high resistance or an open in the ground circuit.
• Right Headlight Control Circuit Voltage (Ignition ON, Headlight OFF) — expected: Less than 1 Volt. Failure: A reading of 1V or greater indicates a short to voltage in the control circuit.
• Right Headlight Control Circuit Resistance to Ground (Ignition OFF) — expected: Infinite resistance (O.L.). Failure: Any reading less than infinite resistance indicates a short to ground in the control circuit.

Hidden / Shadow Codes Worth Checking

• B2699 01: Right Headlamp Control Circuit Short to Battery (see via A professional GM-specific scan tool like GDS2 or Tech2 is required to view these symptom byte sub-codes.)
• B2699 02: Right Headlamp Control Circuit Short to Ground (see via A professional GM-specific scan tool like GDS2 or Tech2 is required to view these symptom byte sub-codes.)
• B2699 04: Right Headlamp Control Circuit Open (see via A professional GM-specific scan tool like GDS2 or Tech2 is required to view these symptom byte sub-codes.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Body Control Module > Control Functions > Exterior Lighting > Low Beam Headlamps — This bidirectional command allows a technician to manually toggle the right headlight ON and OFF directly from the scan tool. If the headlight illuminates with this command, it confirms the BCM, wiring, and bulb are functional, pointing the diagnosis towards a switch or input problem. If it does not illuminate, it confirms the fault lies within the BCM, wiring, or bulb itself.

Wiring & Ground Locations

• Body Control Module (BCM) — Located on the lower left side of the dashboard, accessible by removing the driver's side knee bolster/dash panel. It has seven different colored connectors.. The BCM is the module that controls the headlights and sets code B2699. All diagnostic testing of the control circuit originates or terminates at the BCM connectors.
• G218 — Located on the left front dash defroster deflector area.. This is a primary interior ground point for many dash components. While not the direct headlight ground, a poor connection here can cause various BCM-related electrical issues.
• Headlight Assembly Ground — Each headlight assembly has its own ground wire that attaches to the chassis/radiator core support in the immediate vicinity of the headlight.. A corroded or loose ground at the headlight assembly itself is a common cause for an 'Open Circuit' fault, as the BCM cannot see a complete circuit.
• G110 — On K2XX trucks, this ground is typically located on the left rear corner of the engine compartment, near the firewall and brake booster.. This is a major body harness ground point. While issues are more commonly reported on slightly newer models, ensuring this ground is clean and tight is a key step in diagnosing any complex electrical fault.

OEM Part Supersession History

• 69818, 69818-1 → 69818-2 — The updated 69818-2 kit for Western/Fisher/SnowEx/Blizzard plows features improved, sealed relays to better withstand the elements and prevent moisture intrusion, which could cause faulty operation.
  Heads up: The older kits are directly replaced by 69818-2. This kit is comprised of sub-components including harness 69793-1 and 69817-1, and is often used with isolation module 29070-1.

Model Year Variations Within This Range

• 2014-2015 vs 2016: The 2016 GMC Sierra 1500 received a mid-cycle refresh that included all-new headlight assemblies and a revised front fascia. The headlights from a 2014-2015 model are physically smaller and will not fit a 2016+ truck, and vice-versa. The electrical connectors at the headlight assembly are also different between these two groups. While the BCM control logic for code B2699 is the same, a technician must use the correct wiring diagram and parts for the specific model year they are working on.