U0164 on 2017 GMC Sierra: Lost Communication With HVAC Module Causes and Fixes

What's Unique About the 2017-2017 Gmc SIERRA

On this generation of GMC Sierra and its K2XX platform mates (Silverado, Tahoe, Yukon), the U0164 code is frequently a symptom of a broader network issue rather than a simple failure of the HVAC module. GM has issued multiple Technical Service Bulletins (TSBs) pointing directly at the Serial Data Gateway Module (SDGM) as the root cause. The failure can be a physical one, like loose connector terminals, or a software 'logic lock' where the module freezes. Owners often find this code appears alongside a flood of other 'U' codes, which is a strong indicator that the central SDGM, which acts as a traffic cop for module communication, is the actual point of failure.

Diagnostic Flowchart

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

Symptoms You May Notice

• Climate control panel is inoperative or intermittent
• Cannot adjust temperature, fan speed, or airflow direction
• A/C system does not engage
• Defroster does not work
• Radio or infotainment display may be blank or frozen
• Audible chimes for turn signals or warnings may be absent (as they play through the audio system affected by the SDGM)
• Multiple other warning lights or messages may be present if the SDGM is failing

Most Likely Causes

1. Serial Data Gateway Module (SDGM) Logic Lock or Connector Fault 🔴 High Probability This is a well-documented issue covered by a series of GM Technical Service Bulletins, including #PIT5586B, #PIT5586G, and #20-NA-212. The module can freeze (logic lock), requiring a reset or software update. Additionally, the X1 and X2 connectors at the SDGM are a known weak point where terminals can become loose, bent, or corroded, disrupting communication for multiple modules.
   How to confirm: Scan the vehicle for all DTCs. If U0164 is present with numerous other U-codes (like U0100, U0140, etc.), the SDGM is the prime suspect. As a first step, perform an SDGM reset by pulling fuse F26DL from the underhood fuse block for 60 seconds. If climate functions return, even temporarily, a 'logic lock' is confirmed. If the reset has no effect, a technician will visually inspect the X1 and X2 connectors at the SDGM for any signs of damage or poor pin tension. The SDGM is located under the driver's side of the dashboard.
   Typical fix: If the fuse pull reset worked temporarily, the permanent fix is to have a GM dealer reprogram the SDGM with updated software per the latest TSBs. If the reset failed, the fix is to repair the terminals or connector at the SDGM. This may involve re-seating the connector, cleaning pins, or replacing a specific terminated lead (GM P/N 84619127). If both software and connector repairs fail, the SDGM itself is replaced and programmed.
   Est. part cost: $1-$50 for connector repair parts; $100-$250 for a replacement SDGM.
2. Blown Fuse 🟡 Medium Probability
   How to confirm: Check the fuses related to the HVAC system (often labeled K33), the Serial Data Gateway Module (F26DL in the underhood fuse block), and the Body Control Module (BCM).
   Typical fix: Replace the blown fuse. If the fuse blows again, further diagnosis is needed to find the short circuit.
   Est. part cost: $1-$5
3. Faulty HVAC Control Module ⚪ Low Probability
   How to confirm: This should only be considered after ruling out all network, wiring, and power/ground issues. If U0164 is the only code present, and the module has confirmed power and ground, it may have failed internally. A professional scan tool that can communicate with all other modules but not the HVAC module would point to its failure.
   Typical fix: Replace the HVAC control module. The new module must be programmed by a dealer or a qualified shop to function correctly with the vehicle's specific options.
   Est. part cost: $150-$450

Rare But Worth Checking

• Poor Ground Connection (G218): GM TSB #PIT5405C has identified a poor ground at location G218 (under the driver's side dash near the A-pillar) as a potential cause for a wide range of seemingly unrelated electrical and communication problems on this truck platform, including a blank HVAC display and various communication DTCs. Forum discussions and videos also point to this ground as a fix for flickering lights and random module issues. The insulation mat can get trapped under the ground nut, causing a poor connection. The fix is to remove the nut, trim the insulation away, and securely retighten the ground.
🎬 Watch: How to find and fix the G218 ground connection.

Diagnosis Steps

1. Check the vehicle's battery and charging system. Low voltage (below 12.4V) can cause unpredictable communication errors between modules.
2. Scan for all DTCs in all modules. Note if U0164 appears alone or with many other 'U' codes. A flood of communication codes points towards a network-level problem like the SDGM.
3. Perform the SDGM Reset Test: Locate fuse F26DL in the underhood fuse block. Remove it, wait 60 seconds, and reinstall it. Start the truck and check if HVAC function has returned.
4. If the reset temporarily fixed the problem, the SDGM has a 'logic lock' and requires a software update from a GM dealer. No further physical diagnosis is needed.
5. If the reset did not work, proceed to inspect the fuses for the HVAC system and Body Control Module (BCM).
6. Locate the Serial Data Gateway Module (SDGM) under the driver's side dashboard. Carefully disconnect the battery, then disconnect the SDGM's connectors (specifically the X1 and X2 connectors mentioned in TSB #PIT5586B) and inspect for any bent, loose, or corroded pins.
7. If the SDGM connectors look good, the next step is to check for power and ground at the HVAC control module connector using a multimeter. Pin 1 (RD/WH wire) should have battery voltage, and Pin 7 (BK wire) should have a good ground (less than 1 ohm to chassis).
8. If power and ground are good, a professional will need to use an advanced scan tool to test the CAN bus wiring between the HVAC module and the SDGM to check for opens or shorts.
9. If all wiring and network connections are confirmed to be good, the HVAC control module itself is the likely culprit.

Parts You'll Likely Need

• Serial Data Gateway Module (SDGM) (OEM #13599318) — This module acts as a central hub for network communication. It can fail internally or suffer from software 'logic lock', causing a loss of communication with multiple modules, including the HVAC system. This part requires programming by a dealer after installation.
  Trusted brands: ACDelco (GM Genuine Parts)
  OEM price range: $100-$250
  Aftermarket price range: $80-$200
• HVAC Control Module (OEM #84164476 (Verify by VIN, multiple versions exist)) — While less common, the module itself can fail. This is typically diagnosed only after all network and wiring issues have been ruled out. Part number is highly dependent on vehicle options (auto/manual climate, etc.). Must be programmed after installation.
  Trusted brands: ACDelco, Dorman
  OEM price range: $250-$450
  Aftermarket price range: $150-$300
• Connector Terminal Lead (OEM #84619127) — If a pin is damaged in the SDGM connector, this specific terminated wire may be needed to perform a proper repair instead of replacing the entire harness. [Bulletin #PIT5586B]
  Trusted brands: ACDelco
  OEM price range: $10-$30

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
• U0151 — Lost Communication with Restraints Control Module
• U0155 — Lost Communication With Instrument Panel Cluster (IPC) Control Module
• U0184 — Lost Communication With Radio

Technical Service Bulletins (TSBs) & Recalls

• PIT5586B: Initial bulletin identifying U0164 as part of a group of communication DTCs and pointing to the SDGM X2 connector as a likely cause.
• PIT5586C: Superseded bulletin, reiterating the G218 ground as a potential cause for various electrical issues including blank displays and communication codes.
• PIT5586G / 20-NA-212: Later bulletins that identified a software 'logic lock' in the SDGM as a primary cause, establishing the 'fuse pull reset' as a key diagnostic step and reprogramming as the permanent fix.

Platform-Specific Known Issues

• TSB #PIT5586B specifically calls out that a group of communication codes, including U0164, can be caused by terminal issues in the Serial Data Gateway Module's X1 or X2 connector. The bulletin instructs technicians to check this connector and repair it as needed. [Bulletin #PIT5586B]
• Later TSBs (#PIT5586G, #20-NA-212) expand on this, identifying a software 'logic lock' as a common cause. The prescribed fix is to first attempt a reset, then reprogram the SDGM with updated software before replacing any hardware.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: Approximately 60 Ohms. Failure: A reading of 120 Ohms indicates a break in the circuit or a missing terminating resistor. A reading significantly lower than 60 Ohms (e.g., near 0) indicates a short between the CAN High and CAN Low wires.
• HVAC Control Module (K33) Power Supply Voltage — expected: 12V+ (Battery Voltage). Failure: Voltage below 11.5V or 0V indicates a problem with the power feed wire or a blown fuse. Test at Pin 1 (Red/White wire) of the module connector with ignition on.
• HVAC Control Module (K33) Ground Resistance — expected: Less than 1 Ohm. Failure: Resistance greater than 1 Ohm indicates a poor ground connection. Test between Pin 7 (Black wire) of the module connector and a known-good chassis ground.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Module Diagnostics > K33 HVAC Control Module > Control Functions — This path allows a technician to perform bidirectional tests, such as commanding the A/C compressor, changing blend door positions, or altering fan speed. If the module responds to these commands, it confirms the module itself is likely functional and the problem is in the communication network.
• GM GDS2 (Global Diagnostic System 2): Service Programming System (SPS) — This function is required after replacing either the Serial Data Gateway Module (SDGM) or the HVAC Control Module. The new module must be programmed with the vehicle's VIN and specific configuration to function. Failure to program a new module will result in continued communication errors.
• GM GDS2 (Global Diagnostic System 2): Clear All DTCs — After performing a repair (like fixing a loose terminal or reprogramming a module), this function should be used to clear codes from all modules on the network. A full drive cycle should then be performed to verify the U0164 code does not return.

Wiring & Ground Locations

• Serial Data Gateway Module (SDGM) — Located behind the driver's side lower dashboard, to the left of the steering column. It has a black and a gray connector.. This is the central communication hub. TSBs PIT5586B and PIT5586G identify the X1 and X2 connectors on this module as a primary failure point for U0164 due to poor terminal tension or software 'logic lock'.
• G218 Ground — Under the driver's side of the dashboard, near the A-pillar, often behind the speaker.. This is a critical ground point for the Body Control Module (BCM). TSB #PIT5405C identifies a poor connection here (often due to an insulation mat trapped under the nut) as a cause for a blank HVAC display and numerous communication DTCs, including U0140, which is often seen with U0164.
• K33 HVAC Control Module Connector — Behind the main climate control panel in the center of the dashboard.. This is the main electrical connector for the HVAC module. Pin 1 (RD/WH) is Battery Voltage, and Pin 7 (BK) is Ground. Verifying power and ground here is a key step before condemning the module itself.

Real Owner Repair Stories

• gm-trucks.com forum user (2017 GMC Sierra) — HVAC controls completely dead, radio screen blank, multiple communication codes including U0164.
  ❌ Tried (didn't work) Checking all related fuses., Disconnecting the battery for a hard reset.
  ✅ What actually fixed it The user found TSB PIT5586G and performed the recommended 'fuse pull' reset for the SDGM (fuse F26DL). This temporarily restored all functions, confirming a 'logic lock' that required a dealer software update for a permanent fix.

OEM Part Supersession History

• 13509768, 13524297, 13524298, 13599317 → 13599318 — GM regularly updates service parts to integrate new materials or technologies, often to improve reliability.
  Heads up: Part number 13599318 has been superseded by 84524333 on some platforms. It is critical to use the vehicle's VIN to confirm the correct, most current part number from a GM parts catalog before ordering. Using an incorrect module can lead to programming failures.