U0151 on 2014-2019 GMC Sierra 1500: Lost Communication With Airbag Module Causes & Fixes

What's Unique About the 2014-2019 Gmc SIERRA 1500

On this generation of GMC Sierra and its platform mates (like the Chevy Silverado), there are two well-documented and distinct issues that frequently cause the U0151 code. Manufacturer Technical Service Bulletins (TSBs) point directly to either a physically pinched wire harness behind the left side of the instrument panel (TSB #PIT5288H) or a software 'logic lock' condition in the Serial Data Gateway Module (TSB #PIT5586G). The pinched harness is specifically noted to be crushed between the I/P dash mounting bracket and the body. These platform-specific issues make a thorough wiring inspection and checking for other communication codes essential before assuming the airbag module itself has failed.

Diagnostic Flowchart

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

Generation note: This range covers the third generation (K2XX platform) from 2014-2018. The 2019 model year was a split, with the K2XX sold as the 'Sierra 1500 Limited' and the new fourth generation (T1XX) also being introduced. The cited TSBs and common issues are primarily related to the 2014-2018 and 2019 'Limited' K2XX models.

Symptoms You May Notice

• Airbag warning light is on
• "Service Airbag System" or "Service Restraint System" message on the Driver Information Center (DIC)
• Audible chime when starting the vehicle
• Service Stabilitrak warning light may also appear
• Multiple other warning lights or electrical issues may be present if the cause is a widespread network problem

Most Likely Causes

1. Pinched or Damaged Wiring Harness 🔴 High Probability TSB #PIT5288H specifically identifies the dash harness being pinched between the left I/P dash mounting bracket and the body as a common cause for U0151 and other electrical faults on these trucks.
   How to confirm: Remove the driver's side dash end cover (fuse panel cover). From under the dash, visually inspect the wiring harness where it passes the metal I/P mounting bracket near the parking brake assembly. The TSB notes it can be difficult to see, so check if the harness can move freely away from the bracket.
   Typical fix: Loosen the I/P dash mounting bracket bolts to free the harness. Open the harness loom, repair any cut or chafed wires, and protect the area with anti-abrasion tape (such as woven polyester electrical tape). Re-route the harness to prevent future contact.
   Est. part cost: $5-$25 for wiring repair supplies
2. Serial Data Gateway Module (SDGM) Logic Lock 🟡 Medium Probability TSB #PIT5586G lists U0151 as a potential code when the SDGM enters a 'logic lock' state, where it powers on but stops communicating. This can cause a cascade of 'U' codes.
   How to confirm: This is difficult to confirm without a dealer-level scan tool. A key indicator is the presence of numerous communication codes (U-codes) for various unrelated modules stored at the same time.
   Typical fix: A 'hard reset' by disconnecting the negative battery terminal for 30 minutes may clear the lock. TSB #PIT5586G explicitly states *not* to replace any parts for this condition and to advise the customer of the reset. If that fails, pulling the specific SDGM fuse for 30 seconds can also work, a procedure noted in a similar recall for other GM vehicles.
   Est. part cost: $0 for a reset, $150-$300 for a replacement module if it has failed internally
3. Low Battery Voltage or Poor Grounds 🟡 Medium Probability Communication modules are sensitive to voltage. An aging battery or corroded ground straps can cause intermittent communication failures across the CAN bus, especially during startup. A poor connection at ground G218 (driver's side kick panel) is a known issue on this platform causing widespread electrical problems.
   How to confirm: Test the battery voltage with a multimeter; it should be above 12.4V with the engine off. Load test the battery to check its health. Inspect and clean the main battery terminals and chassis ground points, specifically G218 under the driver's side dash, ensuring no insulation is trapped under the terminal.
   Typical fix: Replace the battery if it fails a load test. Clean or replace corroded ground straps. Secure ground G218, cutting away any interfering dash insulator mat.
   Est. part cost: $150-$300 for a new battery
4. Faulty Sensing and Diagnostic Module (SDM) ⚪ Low Probability While less common than wiring or gateway issues, the SDM (airbag module) can fail internally. A recall on other 2018 GM vehicles (N182155400) noted an issue where the SDM would not power down correctly, causing a U0151 on the next startup. Water intrusion from wet carpets can also damage the module, which is located under the center console on this platform.
   How to confirm: After confirming the wiring, power, and grounds to the SDM are good, and a scan tool still cannot communicate with it, the module itself is suspect.
   Typical fix: Replace the SDM. This requires programming to the vehicle's VIN and configuration, which must be done by a professional with GM's GDS2 software.
   Est. part cost: $300-$600

Rare But Worth Checking

• Blown SDM Fuse: Always a simple first check. The fuse for the airbag system is typically in the instrument panel fuse block or underhood fuse box. A blown fuse indicates an underlying electrical short that must be found.
• Aftermarket Accessories: Improperly installed remote starters, alarms, audio equipment, or even seat conversions can interfere with the CAN bus network, causing communication codes like U0151.
• Poor SDGM Connector Terminals: Early versions of TSB PIT5586 also pointed to bent, backed out, or loose terminals at the X1 or X2 connectors of the Serial Data Gateway Module as a potential cause for a host of communication issues, including U0151.

Diagnosis Steps

1. Check Battery Health: Ensure battery voltage is stable and above 12.4V (engine off). Have it load-tested, as weak batteries are a common source of communication faults.
2. Perform a Full Vehicle Scan: Use a capable OBD-II scanner to check for codes in ALL modules. Note if U0151 is isolated or if many other 'U' codes are present, which would point to a gateway or network-wide issue.
3. Check the SDM Fuse: Locate the airbag/SDM fuse in the instrument panel or underhood fuse block and verify it's not blown and has power on both sides.
4. Inspect Left Instrument Panel Harness: This is the highest probability cause. Remove the driver's side dash end panel. From underneath the dash, carefully inspect the large wiring harness where it passes the metal I/P mounting bracket near the parking brake pedal. Check for chafing, pinching, or cuts as detailed in TSB #PIT5288H.
🎬 See this walkthrough for finding and fixing the pinched harness.
5. Attempt a Hard Reset: Disconnect the negative battery terminal for at least 30 minutes to reset all modules. This can clear a software 'logic lock' in the SDGM as per TSB #PIT5586G.
6. Test CAN Bus Network: If the problem persists, use a multimeter to check the resistance between pins 6 and 14 of the OBD-II port (with the battery disconnected). A healthy high-speed network should read approximately 60 ohms.
7. Verify Power and Ground at the SDM: If you can access the SDM connector (under the center console), use a multimeter to confirm it is receiving proper battery voltage and has a good ground connection.
8. Professional Diagnosis: If the above steps do not identify the cause, the vehicle should be taken to a qualified technician who can perform advanced network diagnostics (like checking for loose SDGM terminals or testing the Communication Enable circuit) and determine if the SDM, SDGM, or another module needs reprogramming or replacement.

Parts You'll Likely Need

• Sensing and Diagnostic Module (SDM) (OEM #13518051) — This is the airbag control module. It is replaced only after all wiring, power, and ground issues have been ruled out. Part number is an example for the K2XX platform and should be verified by VIN.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $300-$600
  Aftermarket price range: $200-$450
• Serial Data Gateway Module (SDGM) — This module controls data flow between networks. It can fail or enter a 'logic lock' state, causing widespread communication codes. Replacement requires programming.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $150-$300
  Aftermarket price range: $100-$200

Related Codes That Often Appear With This One

• U0140 — Lost Communication With Body Control Module. Often appears with other U-codes when there is a network-wide issue, like a problem with the Serial Data Gateway Module or a faulty ground like G218.
• U0100 — Lost Communication With ECM/PCM. Seeing multiple communication codes together points towards a central network problem (wiring, gateway module) rather than a single failed module.
• U0077 — Lost Communication With... (varies). This code is specifically mentioned alongside U0151 in TSB PIT5288H related to the pinched harness.

Technical Service Bulletins (TSBs) & Recalls

• PIT5288H: Details the pinched dash harness issue. It instructs technicians to inspect the harness behind the left side of the instrument panel, near the mounting bracket, for damage causing a variety of electrical issues including U0151.
• PIT5586G: Describes a 'logic lock' condition in the Serial Data Gateway Module (SDGM) that can cause a flood of communication DTCs, including U0151. The primary fix is a reset, and the bulletin advises *not* to replace modules for this specific condition.
• N182155400: A recall for the 2018 GMC Terrain (not Sierra) but relevant as it describes a similar U0151 symptom caused by the SDM not powering down correctly. The fix involves an SDM fuse pull reset or reprogramming.

Platform-Specific Known Issues

• TSB #PIT5288H documents that a pinched wire harness in the left instrument panel area can cause U0151 and other communication codes on 2014 models.
• TSB #PIT5586G notes that a 'logic lock' of the Serial Data Gateway Module can trigger a wide range of communication DTCs, including U0151.

Mechanic-Grade Diagnostic Values

• Communication Enable Circuit (5986) Voltage Under Load — expected: At least 11.0V DC. Failure: Voltage below 11.0V when a 194 incandescent bulb (~250mA load) is connected between the circuit and a good ground indicates high resistance in the circuit.
• High-Speed CAN Bus Termination Resistance — expected: 60 Ω (Ohms) ± 5 Ω. Failure: A reading of ~120 Ω indicates an open on one of the terminating resistors or the wiring to it. A reading significantly below 60 Ω suggests a shorted wire.
• System Operating Voltage at Module — expected: 9V to 16V DC. Failure: Voltage below 9V can cause modules to drop offline and set communication codes.

Hidden / Shadow Codes Worth Checking

• U0151 71: Lost Communication With Restraints Control Module - Invalid Serial Data Received. This indicates the module is communicating, but the data it's sending is corrupt or not understood by other modules. (see via GM GDS2 or other professional-grade scan tool that can read manufacturer-specific symptom bytes.)
• U0151 7F: Lost Communication With Restraints Control Module - Erratic. This suggests the communication from the module is intermittent or unstable. (see via GM GDS2 or other professional-grade scan tool that can read manufacturer-specific symptom bytes.)

Scan Tool Commands That Help

• GDS2: Setup SDM Part Number in BCM — After installing a new Sensing and Diagnostic Module (SDM), this function must be run to make the Body Control Module (BCM) recognize the new airbag module.
• GDS2: Configure New Module — This is a general configuration function used when a new SDM is installed to load the correct vehicle-specific setup into the module.
• GDS2: Enable Deployment Loops — After a new SDM is programmed, this final step activates the airbag and pretensioner circuits. The module will store open circuit codes until this is completed.

Wiring & Ground Locations

• SDM (Sensing and Diagnostic Module) — Under the front center console or center seat. Requires removal of the console for access.. This is the module that has lost communication. Physical access is needed to test its power, ground, and communication wires, or to replace it.
• G218 — Driver's side A-pillar, behind the instrument panel/kick panel area, near the parking brake assembly.. This is a major ground point for the Body Control Module (BCM). TSB PIT5405C identifies a poor connection here (often due to trapped dash insulation) as a cause for multiple communication codes, as the BCM is a central communication hub.
• SDGM (Serial Data Gateway Module) — Behind the instrument panel, often accessible after removing the glove box.. This module acts as a bridge between different CAN bus networks. A logic lock, power/ground issue, or bad connector terminal at this module can prevent communication with the SDM.
• Circuit 5986 (Communication Enable) — This is a wire, not a single component. It runs from the BCM to multiple other modules, including the SDM. It is often a Pink wire on GM schematics.. This circuit provides a 12V 'wake-up' signal from the BCM to the SDM. If this circuit is open or shorted, the SDM will not power on to communicate, setting a U0151 even if the CAN bus wiring is perfect.

Real Owner Repair Stories

• YouTube user 'Chevy Dude' (2014-2018 Chevrolet Silverado High Country) — Headlights and dash lights flickering, especially when using brake or turn signal. Intermittent stalling while turning at low speeds. Multiple warning lights on dash including 'Park Assist Disabled' and power steering warnings.
  ❌ Tried (didn't work) Battery and alternator tested good.
  ✅ What actually fixed it The problem was a poor connection at ground G218, located on the driver's side behind the dash. Sound deadening/insulation material was trapped under the ground lug, causing an intermittent connection. The fix was to access the ground, remove the nut, trim away the interfering insulation, and retighten the ground nut.

OEM Part Supersession History

• 13590222, 13592892, 13594414 → 13518051 — Standard part revision and consolidation for the K2XX platform Sensing and Diagnostic Module (SDM).
  Heads up: While later part numbers are generally backward compatible within the same generation, always verify the correct part number for the specific VIN and vehicle options using a dealer catalog before ordering.

Model Year Variations Within This Range

• 2019-2020: A specific software issue in the Brake System Control Module (BSCM) can cause it to stay powered on after shutdown, leading it to set a U0151 and other communication codes at the next startup. This is unique to these model years and is addressed by TSB PIT5735B.