U0164 on 2017-2019 Chevrolet Silverado 1500: HVAC Communication Loss Causes and Fixes

What's Unique About the 2017-2019 Chevrolet SILVERADO 1500

For this generation of Silverado (primarily the K2XX platform), U0164 is frequently a symptom of a larger network problem, not an isolated failure of the HVAC controller. GM routes communications through a central hub called the Serial Data Gateway Module (SDGM), which is a known failure point. This module, located behind the driver's side lower dash panel, can freeze ('logic lock') or suffer from poor electrical connections in its X1 and X2 connectors, causing a cascade of communication codes, including U0164, as documented in manufacturer TSBs.

Diagnostic Flowchart

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

Generation note: The 2017-2019 range covers two Silverado generations. The 2017-2018 models and the 2019 'LD' (Limited/Legacy) model are on the K2XX platform, where the Serial Data Gateway Module (SDGM) issue is a well-documented cause for this code. The redesigned 2019 models are on the newer T1XX platform, which has a different network architecture but can still suffer from module or wiring failures.

Symptoms You May Notice

• Climate control panel is unresponsive or blank.
• Inability to control fan speed, air temperature, or vent direction.
• A/C system will not turn on.
• Defroster is inoperative.
• Multiple other 'U' (communication) trouble codes may be stored at the same time, often accompanied by various service messages on the instrument panel.
• Radio display may be blank or not show temperature.

Most Likely Causes

1. Serial Data Gateway Module (SDGM) Fault 🔴 High Probability As identified in GM Technical Service Bulletin #PIT5586G, the SDGM on the K2XX platform is prone to 'logic lock' (software freeze) and poor pin tension or corrosion in its X1 and X2 connectors, causing widespread network communication failures.
   How to confirm: A professional scan tool will show lost communication with multiple vehicle modules, not just the HVAC system. Visually inspect the SDGM connectors (located behind the driver's side knee bolster) for any backed-out, bent, or corroded pins. If a battery disconnect temporarily restores function, a 'logic lock' is the likely cause.
   Typical fix: First, attempt a 'logic lock' reset by disconnecting the battery for 30 minutes. If that fails, the official procedure involves dealer-level reprogramming of the SDGM with updated software per TSB 20-NA-212. If reprogramming is unsuccessful or connector damage is found, the module or its connector terminals must be replaced.
   Est. part cost: $50-$150
2. Blown Fuse or Poor Power/Ground 🟡 Medium Probability TSB #18-NA-358 notes that poor battery cable connections or a bad Body Control Module (BCM) ground at location G218 can cause various communication codes. G218 is located under the driver's side dash near the A-pillar.
   How to confirm: Check the underhood and interior fuse boxes (left and right side of dash) for any fuses related to the HVAC, BCM, SDGM, or Radio. Use a multimeter to verify stable voltage (12V+) and a solid ground connection (less than 0.1 Ω) at the HVAC control module's connector.
   Typical fix: Replace the blown fuse or repair the compromised wiring in the power or ground circuit. Clean and tighten the G218 ground connection if it is loose or corroded.
   Est. part cost: $1-$20
3. Faulty HVAC Control Module ⚪ Low Probability
   How to confirm: This is diagnosed by exclusion. If the SDGM is confirmed good, all network wiring is intact, and the module has proper power and ground but still won't communicate with a scan tool (especially a bidirectional one), the module itself has likely failed.
   Typical fix: Replace the HVAC control module, which is located in the center dash stack. 🎬 Watch: How to access the radio and HVAC control panel. The new module will require programming by a dealer or qualified shop to function correctly.
   Est. part cost: $150-$400

Rare But Worth Checking

• Damaged CAN Bus Wiring: A short or open in the communication wiring harness can isolate the HVAC module. This can be caused by previous repairs, rodent damage, or chafing against a bracket behind the dash. Diagnosis involves checking for continuity and resistance on the data lines with a multimeter.
• Aftermarket Device Interference: Improperly installed remote starters, alarms, or audio equipment tapped into the vehicle's data network can disrupt communication and set U-codes.

Diagnosis Steps

1. Scan the vehicle for all stored trouble codes in all modules. Note if multiple 'U' codes are present, which points to a network-wide issue originating from a central point like the SDGM.
2. Perform a hard reset by disconnecting the negative battery terminal for at least 30 minutes to clear any potential 'logic lock' in the SDGM.
3. Inspect all fuses related to the HVAC system, radio, SDGM, and Body Control Module (BCM) in the interior (both driver and passenger side) and underhood fuse panels.
4. Locate and inspect the Serial Data Gateway Module (SDGM). On K2XX trucks, it's located behind the driver's side lower dash/knee bolster. Carefully check its X1 and X2 connectors for corrosion, moisture, or loose/damaged pins as per TSB PIT5586G.
5. Inspect key ground connections, particularly G218 (under the driver's dash near the A-pillar), for tightness and corrosion, as noted in TSB 18-NA-358.
6. If the SDGM and its connections appear fine, inspect the wiring and connector at the back of the HVAC control module in the center dash.
7. If no obvious wiring or connection faults are found, the vehicle should be taken to a qualified technician who can perform network diagnostics and attempt to reprogram the SDGM or other modules as required by GM service bulletins.

Parts You'll Likely Need

• Serial Data Gateway Module (SDGM) (OEM #13542838, 13540083) — This module is the most common point of failure for network communication codes like U0164 on the 2017-2019 K2XX platform, as noted in TSBs. Part number can vary; 13542838 is a common replacement.
  Trusted brands: ACDelco (GM Genuine Parts)
  OEM price range: $60-$110
  Aftermarket price range: $40-$150
• HVAC Control Module (OEM #84542734) — If the SDGM and wiring are confirmed to be good, the HVAC module itself is the next logical part to replace. Part number varies by year and options; 84542734 is for some 2019+ models.
  Trusted brands: ACDelco, Dorman
  OEM price range: $200-$400
  Aftermarket price range: $150-$300

Related Codes That Often Appear With This One

• U0100 — Lost Communication With ECM/PCM
• U0101 — Lost Communication with TCM
• U0140 — Lost Communication With Body Control Module
• U0155 — Lost Communication With Instrument Panel Cluster (IPC) Control Module
• U0184 — Lost Communication With Radio

Technical Service Bulletins (TSBs) & Recalls

• PIT5586G: Notes that U0164 can be caused by a logic lock or connector issue at the Serial Data Gateway Module.
• 20-NA-212: Provides instructions for reprogramming the SDGM with updated software as a corrective action.
• 18-NA-358: Points to poor battery cable or BCM ground connections (G218) as a potential cause for communication codes.

Platform-Specific Known Issues

• TSB #PIT5586G: Network Communication Loss: This bulletin documents a condition where a 'logic lock' of the Serial Data Gateway Module or issues with its X1 and X2 connectors can cause U0164 along with a host of other communication codes. The recommended procedure is to first attempt a reset, then inspect the connectors, and finally reprogram or replace the module.
• TSB #18-NA-358: Poor Ground Connection: Notes that various communication DTCs, including U0164, can be set due to high resistance in battery cables or a poor BCM ground connection at location G218.
• Real-World Repair Story: Blown Fuse: In one documented case on a 2018 Silverado with multiple communication codes and a blank radio (symptoms of SDGM failure), the actual cause was a single blown 10-amp fuse in the passenger side interior fuse block. This highlights the importance of checking all related fuses before replacing expensive modules.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: 60 Ohms (with battery disconnected). Failure: A reading of 120 Ohms indicates a missing termination resistor or a break in the wiring. A reading near 40 Ohms or less suggests an extra termination resistor is present or a module is shorted.
• CAN High (CAN-H) Voltage — expected: Approx. 2.5V to 3.5V (fluctuating with data). Failure: A static voltage or one outside this range indicates a wiring short/open or a faulty module transceiver.
• CAN Low (CAN-L) Voltage — expected: Approx. 2.5V to 1.5V (fluctuating with data). Failure: A static voltage or one outside this range indicates a wiring short/open or a faulty module transceiver.
• Ground Circuit Resistance — expected: Less than 0.1 Ohms. Failure: Higher resistance indicates a poor ground connection, which is a known cause of communication codes per TSB 18-NA-358.

Hidden / Shadow Codes Worth Checking

• U-code with Symptom Byte 71: Indicates 'Invalid Data Received'. This means a module is receiving data from another module (like the HVAC module) that it deems invalid or corrupt. TSB PIT5569A advises that this code often points to a fault in the *sending* module's inputs (e.g., a sensor connected to the HVAC module), not necessarily the receiving module. (see via GM's GDS2 (Global Diagnostic System 2) software will display the main DTC followed by a two-digit symptom code.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Module Diagnostics > SDGM > Programming/Setup — This function is required after replacing the Serial Data Gateway Module. The new module must be programmed to the vehicle's VIN and configuration using the Service Programming System (SPS) accessed through GDS2.
• GDS2: Clear All DTCs — After performing a repair like fixing a ground or replacing a module, use this function to clear codes from all modules simultaneously. This is crucial for verifying the fix, as a lingering code in one module can still cause network symptoms.
• GDS2: Data Display > HVAC Control Module — To view live data from the HVAC module. If you can access this screen and see data changing (e.g., pressing buttons on the control panel), it confirms the module is powered and partially communicating, pointing away from a complete module failure.

Wiring & Ground Locations

• G218 — Under the driver's side of the dash, near the A-pillar, often behind the dash-end trim panel.. This is a primary ground point for the Body Control Module (BCM). TSBs PIT5405C and 18-NA-358 identify a poor connection here (often due to sound-deadening material getting trapped under the ground nut) as a cause for widespread communication codes, including U0164.
• Passenger Side Frame Ground — On the passenger side frame rail, visible after turning the wheel and looking behind the fender liner.. Multiple forum and video sources point to a critical ground connection on the passenger side frame that can become corroded or loose, causing a variety of electrical issues, including flickering lights and communication faults similar to those seen with U0164.
• SDGM Connectors X1 & X2 — On the Serial Data Gateway Module, located behind the driver's side knee bolster/lower dash panel.. TSB PIT5586G specifically calls out inspecting these connectors for loose, bent, or corroded terminals as a primary diagnostic step for U0164 and other network codes.

Real Owner Repair Stories

• Reddit user in r/MechanicAdvice (2009 Cadillac Escalade ESV (similar GM network architecture)) — Dash lit up with multiple communication codes (U0100, U0101, U0121, U0140) and vehicle entered limp mode after driving through deep water.
  ❌ Tried (didn't work) Initial assumption was water damage to a module.
  ✅ What actually fixed it The locking lever on the large electrical connector to the ECM (Engine Control Module) had come loose, causing the plug to barely make contact. Re-seating and locking the connector resolved all communication codes.
• YouTube video by Dustin T (2014 Silverado High Country (K2XX Platform)) — Flickering dash/headlights, radio/HVAC blanking out, Service Stabilitrak messages, intermittent loss of power steering, engine stalling at low speeds.
  ❌ Tried (didn't work) Testing the battery and alternator, which both checked out as good.
  ✅ What actually fixed it The G218 ground under the driver's side dash was loose due to sound insulation material being caught under the ground nut. Cleaning the contact area and tightening the nut resolved all electrical issues.

OEM Part Supersession History

• 13536364 → 13540083 — Standard part revision and update by the manufacturer.
  Heads up: The newer part number 13540083 is the correct replacement for the older 13536364. No incompatibility is noted; using the latest version is recommended.

Model Year Variations Within This Range

• 2019: In 2019, Chevrolet sold two different Silverado 1500s. The 'Silverado 1500 LD' (or Limited) was a carryover of the previous K2XX platform, which has the known SDGM and G218 ground issues. The all-new 'Silverado 1500' (new body style) is on the T1XX platform with a different network architecture (Global B) and does not use the same SDGM, meaning the common causes are different. It is critical to identify which 2019 model is being diagnosed.