U0422 on 2019-2021 GMC Acadia: Invalid BCM Data Causes and Fixes

What's Unique About the 2019-2021 Gmc ACADIA

The second-generation GMC Acadia and its platform mates are known for a specific issue where the HVAC drain hose can leak water into the passenger compartment, directly onto or near the Body Control Module (BCM). This makes water intrusion a primary suspect for code U0422 on these vehicles, a problem corroborated by owner complaints and the subject of a detailed GM Technical Service Bulletin (21-NA-183). This TSB outlines the inspection and repair, which involves securing the hose with a simple tie strap. Additionally, GM has issued several TSBs for related models concerning software anomalies that can trigger a U0422 code, sometimes as a harmless history code due to high network traffic at startup. A customer satisfaction program (N192282480) was also issued for 2019 Acadias for BCM wiring damage that could occur from the installation or removal of an aftermarket LoJack alarm system.

Diagnostic Flowchart

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

Symptoms You May Notice

• "No remote detected" message on the driver information center.
• Vehicle has trouble starting or is a no-crank, no-start.
• Adaptive Cruise Control is unavailable or malfunctioning.
• "Service Stabilitrak" message is illuminated on the DIC.
• Power door locks, windows, or interior lights work erratically or not at all.
• Horn or hazard flashers operate unexpectedly.
• Instrument cluster gauges may flicker or go blank intermittently.

Most Likely Causes

1. Water Intrusion Damaging the BCM 🔴 High Probability A well-documented issue on this platform involves the HVAC drain hose leaking water into the area where the BCM is located. GM TSB 21-NA-183 provides a detailed procedure for this exact problem. Owner forums for GM vehicles frequently cite water intrusion as the cause of BCM failure.
   How to confirm: Check for dampness or water stains on the driver's side carpet and under the dashboard. Per TSB 21-NA-183, a technician will remove the floor console extension panels to observe the HVAC drain hose connection while the A/C is running. 🎬 Watch: How to clear a blocked HVAC drain hose yourself. If the BCM is removed, its case can be opened to check for visible internal corrosion on the circuit board.
   Typical fix: First, repair the source of the water leak. TSB 21-NA-183 instructs technicians to secure the HVAC drain hose with a tie strap (GM P/N 11509086) to prevent further leakage. If the BCM shows any signs of internal or external corrosion, it must be replaced and programmed to the vehicle.
   Est. part cost: $250-$500 for BCM, <$1 for tie strap
2. Control Module Software Anomaly 🟡 Medium Probability GM has issued multiple TSBs where U0422 is caused by a software glitch. TSB 16-NA-407 states that U0422 can be set as a history code by the Chassis Control Module (CCM) during startup due to high bus traffic and should be ignored if it is not active and not accompanied by DTCs U1534 or U1538. TSB PIT5845 also mentions U0422 on the 2019 Acadia related to the adaptive cruise system.
   How to confirm: A GM dealer or a qualified shop with access to GM's software can check if the code is in history and if any other codes are present. They can also check if the EBCM, CCM, or BCM have pending software updates.
   Typical fix: If the code is only in history with no related codes, the fix is to clear and ignore it per TSB 16-NA-407. If related to a Stabilitrak message, the EBCM may need a software update per the precedent set by TSB 19-NA-202. This is a dealer or specialist-level repair.
   Est. part cost: $0
3. Low Battery Voltage or Poor Grounds 🟡 Medium Probability Modern vehicles with multiple control modules are sensitive to voltage fluctuations. A weak battery or a bad ground connection can cause unpredictable communication errors between modules, triggering codes like U0422.
   How to confirm: Test the battery voltage at rest (should be above 12.4V). With the engine running, check the alternator output (typically 13.5V-14.5V). Perform a voltage drop test on the main battery and BCM ground connections; voltage at the ground pins should not exceed 0.250 volts.
   Typical fix: Replace the weak battery, faulty alternator, or clean and repair the corroded ground connection.
   Est. part cost: $150-$600
4. Faulty Body Control Module (BCM) ⚪ Low Probability While less common than water damage or software issues, the BCM can fail internally due to electronic component degradation. This is a diagnosis of exclusion.
   How to confirm: This is diagnosed by exclusion. If the water leak has been ruled out, all wiring, power/ground connections, and software are confirmed to be good, but the BCM continues to send invalid data, the module itself is likely faulty.
   Typical fix: Replace the Body Control Module and program the new unit to the vehicle's VIN and specific options.
   Est. part cost: $250-$500

Rare But Worth Checking

• Wiring Harness Issue: A chafed or corroded wire in the CAN bus network can disrupt communication between modules. This is less common than the above causes but should be investigated if other diagnostics are inconclusive, especially if codes U1534 or U1538 are present, which point to door wiring issues. GM Customer Satisfaction Program N192282480 also notes that BCM wiring on 2019 Acadias could be damaged by the installation/removal of aftermarket LoJack systems.

Diagnosis Steps

1. Scan all vehicle modules for stored trouble codes. Note which module is reporting code U0422 and whether the code is 'Active/Current' or 'History'.
2. Consult TSB 16-NA-407: If U0422 is a history code and DTCs U1534 or U1538 are NOT present, the code can likely be cleared and ignored as a startup anomaly.
3. If the code is active or other symptoms are present, check the battery. Ensure it is fully charged and passes a load test. A resting voltage should be above 12.4V.
4. Perform a water leak inspection per TSB 21-NA-183: Remove the driver's side console extension panel and inspect the footwell for moisture. Run the A/C on high and observe the HVAC drain hose connection for drips.
5. If water is suspected or confirmed, locate the BCM (under the driver's side of the dash, near the gear selector) and inspect its connectors for any green or white corrosion. If possible, remove and open the BCM to check for internal corrosion on the circuit board.
6. If no water is found, verify power and ground connections at the BCM are clean, tight, and show proper voltage using a multimeter. Check for voltage drop on ground pins, which should not exceed 0.250V.
7. Check for any applicable Technical Service Bulletins (TSBs) or Customer Satisfaction Programs (like N192282480 for damaged wiring) related to U0422 for your specific VIN. A software update for the EBCM or BCM may be the required fix.
8. If no water damage or software updates apply, a technician will need to perform advanced network diagnostics on the CAN bus. This includes checking the bus resistance between pins 6 and 14 of the DLC, which should be approximately 60 ohms with the battery disconnected.

Parts You'll Likely Need

• Body Control Module (BCM) (OEM #84922494) — The BCM can be damaged internally by water intrusion, a known issue on this vehicle, or fail electronically, causing it to send invalid data. This part number is listed as a supersession for 2020+ models.
  Trusted brands: ACDelco (Genuine GM)
  OEM price range: $300-$500
  Aftermarket price range: $200-$400
• Automotive Battery — A weak or failing battery is a common cause of various communication codes, including U0422, due to unstable voltage supplied to the modules.
  Trusted brands: ACDelco, Interstate, DieHard
  OEM price range: $200-$350
  Aftermarket price range: $150-$250
• Tie Strap (OEM #11509086) — This specific part (a zip tie) is called for in TSB 21-NA-183 to secure the HVAC drain hose and prevent the common water leak that damages the BCM.
  Trusted brands: ACDelco (Genuine GM)
  OEM price range: <$5
  Aftermarket price range: <$1

Related Codes That Often Appear With This One

• C0277 — This code for the Brake Pedal Position Sensor can be set along with U0422 due to a software anomaly in the EBCM, as described in GM TSB 19-NA-202 for other models, often accompanied by a 'Service Stabilitrak' message.
• U1534 / U1538 — These BCM fault codes for door switch circuits may accompany U0422. TSB 16-NA-407 notes that if U0422 is present with these codes, it indicates a real fault that needs investigation, not just a startup glitch.

Technical Service Bulletins (TSBs) & Recalls

• 21-NA-183: The most current bulletin detailing the diagnosis and repair of a water leak from the HVAC drain hose onto the BCM. Advises adding a tie strap and replacing the BCM if corroded.
• PIT5845: For diagnosing U0422 in the EBCM when issues with Adaptive Cruise Control are present.
• 16-NA-407: Details that U0422 can sometimes be a non-actionable history code set by the Chassis Control Module (CCM) during startup and should be ignored unless other specific codes are present.
• 19-NA-202: While for the Chevy Malibu, it shows a precedent for U0422 being caused by a software anomaly in the EBCM that can be fixed with a re-program, often related to Stabilitrak messages.

Platform-Specific Known Issues

• An owner of a 2020 GMC Acadia reported code U0422 along with key fob detection and starting problems, and noted that forums suggest a water leak could be the cause.
• GM TSB #PIT5845 specifically addresses diagnosing U0422 in the EBCM related to the adaptive cruise control system on the 2019 Acadia.
• GM TSB #21-NA-183 (which supersedes 16-NA-407 for this issue) describes a potential water leak from the HVAC drain hose that can damage the BCM.
• GM Customer Satisfaction Program N192282480 was issued for 2019 Acadias due to potential BCM wiring damage from the installation/removal of aftermarket LoJack alarm systems.

Mechanic-Grade Diagnostic Values

• High-Speed CAN Bus Network Resistance — expected: Approximately 60 Ohms. Failure: A reading of 120 Ohms indicates a missing termination resistor or an open in the bus. A reading significantly less than 60 Ohms (e.g., 40 Ohms) indicates an extra termination resistor or a short between the CAN lines.
• BCM Ground Pin Voltage Drop — expected: Less than 0.250 Volts (250 mV). Failure: A voltage higher than 0.250V indicates a poor ground connection, which can cause the module to function incorrectly.
• CAN Bus Voltage (Key On) — expected: CAN High (Pin 6 at DLC) and CAN Low (Pin 14 at DLC) should both measure approximately 2.5V to ground when there is no data being transmitted.. Failure: A steady 0V or 12V on either line indicates a short to ground or power, respectively.

Hidden / Shadow Codes Worth Checking

• U0422-71: This is a sub-code with a symptom byte. The '-71' indicates 'Invalid Data' and points more specifically towards an internal hardware or logic failure within the BCM or Serial Data Gateway Module (SDGM), rather than a simple wiring break. (see via Requires a professional-grade scan tool capable of reading GM-specific symptom bytes, such as the GM GDS2 (Global Diagnostic System 2).)

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Module Diagnostics > Body Control Module > Control Functions — This function allows a technician to perform bidirectional tests by commanding BCM outputs directly from the scan tool. For example, you can command the headlights on, operate power windows, or cycle door locks to verify if the BCM is capable of controlling its circuits, helping to distinguish between a faulty BCM, a wiring issue, or a bad component (like a window motor).
• GM GDS2 (Global Diagnostic System 2): Vehicle DTC Information — This is the first step in diagnosis. It performs a full network scan to see which modules are reporting codes and, more importantly, which modules are not communicating at all. This helps build a complete picture of the network's health.
• GM GDS2 (Data Bus Diagnostic Tool): Message Monitor — Used to diagnose intermittent issues or battery drains related to network problems. It passively monitors the CAN bus with the key off to see which modules are 'waking up' and communicating when they should be asleep, which can help track down a module that is corrupting the bus.

Wiring & Ground Locations

• DLC Pins 6 & 14 — The Data Link Connector (OBD-II port) under the driver's side dashboard.. Pin 6 is the CAN High (+) line and Pin 14 is the CAN Low (-) line for the high-speed GMLAN bus. Technicians test resistance and voltage here to quickly assess the overall health of the primary communication network connecting the BCM, ECM, EBCM, and other critical modules.
• BCM Connector X3 (or C3) — A connector on the back of the instrument panel fuse block (junction block).. On some GM platforms, disconnecting this connector can isolate the CAN bus into two halves. This is a powerful diagnostic technique to determine which section of the vehicle's wiring or which group of modules contains the fault. If communication is restored to one half of the bus after disconnecting X3, the problem lies in the disconnected section.
• G300 — A common ground point located behind the right kick panel in the passenger footwell on related GM platforms.. The BCM and other nearby modules may use this as a primary ground point. A loose or corroded G300 can cause a high-resistance ground path, leading to unpredictable module behavior and communication codes like U0422.

Real Owner Repair Stories

• YouTube video by 'GMC Arcadia Body Control Module Faults- BCM Codes' (GMC Acadia (generation not specified, but shows BCM under center console)) — Multiple trouble codes from various modules, vehicle not recognizing it is in Park.
  ❌ Tried (didn't work) Initial scan showed codes everywhere.
  ✅ What actually fixed it The root cause was coffee with cream and sugar spilled into the center console, which dripped directly onto the BCM located underneath the gear selector. The BCM connectors showed green corrosion ('green crusties'). The fix required replacing the BCM and the gear selector switch assembly.

OEM Part Supersession History

• Multiple (e.g., 22860591, 25892622, 84562763) → 84922494 — GM consolidates part numbers over time to account for hardware revisions, software updates, and to streamline inventory. This part number has superseded over a dozen previous numbers.
  Heads up: While many older part numbers are superseded by 84922494, it is critical to use a VIN-lookup tool to confirm the correct BCM for a specific vehicle. Using a BCM from a vehicle with different options (e.g., different lighting, sunroof) can cause features to not work even after programming.

Model Year Variations Within This Range

• 2020-2021: The 2020 model year introduced a significant mid-cycle refresh. Key changes included a new 9-speed automatic transmission (replacing the 6-speed) and an Electronic Precision Shift system, which uses buttons instead of a traditional gear lever. This change in shifter technology directly impacts BCM inputs and logic. The infotainment system was also updated, and a new 2.0L turbo engine option was added. These electrical and powertrain changes mean that diagnostics and parts (like the BCM) may differ slightly from the 2019 model.