P2724 on 2019-2020 GMC Sierra 1500: Rear Wheel Lock-Up and TCM Failure

What's Unique About the 2019-2020 Gmc SIERRA 1500

While P2724 generically points to a solenoid, on the 2019-2020 GMC Sierra 1500 (and its Chevrolet Silverado counterpart) equipped with the 8-speed automatic transmission (RPO MQE) 🎬 Watch: A deep dive into the 8L90 transmission's design flaws., this code has a well-documented and severe platform-specific issue. General Motors issued Technical Service Bulletin #PIP5646D (later updated to #23-NA-018) that directly links P2724, along with codes P2727 and P2729, to a dangerous symptom: the rear wheels locking up at low speeds after the vehicle has been sitting ('hot soak'). The bulletin identifies the root cause not as a simple solenoid failure, but as an internal malfunction within the Transmission Control Module (TCM) itself, caused by wire bonds moving under high current and making contact.

Diagnostic Flowchart

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

Symptoms You May Notice

• Rear wheels locking up at low speeds, especially after a hot soak (parked for 30 mins to 4 hours after driving).
• Vehicle comes to a sudden stop as if the brakes were applied or it was shifted into Park.
• Check Engine Light (Malfunction Indicator Lamp) is on.
• Harsh or erratic shifting.
• Transmission may enter 'limp mode,' limiting available gears.
• Transmission overheating warning.
• May lose the ability to reverse.

Most Likely Causes

1. Faulty Transmission Control Module (TCM) 🔴 High Probability → Shop Transmission Assembly A GM Technical Service Bulletin (#PIP5646D, updated by #23-NA-018) explicitly identifies an internal TCM failure as the cause for this condition on this specific vehicle. A customer satisfaction program (#N192272400) was also issued, stating an intermittent short circuit can occur inside the TCM due to wire bonds moving under high current and thermal load. This is a known defect for this platform.
   How to confirm: Diagnosis by a professional technician following the TSB guidelines. The presence of code P2724 (or P2727, P2729) combined with the rear wheel lock-up symptom is the primary indicator. The TSB specifically instructs technicians NOT to clear DTCs.
   Typical fix: Replace the Transmission Control Module (TCM). 🎬 See this walkthrough on finding and replacing the hidden TCM. The new module must be programmed by a dealer or qualified shop with access to GM's Service Programming System (SPS).
   Est. part cost: $300-$600
2. Failed Pressure Control Solenoid 'E' ⚪ Low Probability → Shop Transmission Clutch Pressure Control Solenoid While the code directly names the solenoid, on this platform it is most often a symptom of the TCM failure. A solenoid failure is possible but much less likely to be the root cause given the known TSB and customer satisfaction program specifically identifying the TCM.
   How to confirm: A technician would need to drop the transmission pan to access the valve body and test the solenoid's resistance and function directly. This should only be done after ruling out the more likely TCM issue by checking for the applicability of TSB #23-NA-018. The pressure control solenoids in the 8L90 should measure between 4.5–5.5 ohms.
   Typical fix: Replace the solenoid pack or the individual solenoid, which is part of the valve body assembly. This also involves replacing the transmission fluid and filter.
   Est. part cost: $150-$400
3. Low or Dirty Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly Incorrect fluid level or contaminated fluid can cause a variety of transmission problems, including erratic pressure and solenoid faults. However, this is unlikely to be the root cause of the specific wheel lock-up symptom described in the TSB.
   How to confirm: Check the transmission fluid level and condition according to the manufacturer's procedure. The fluid should be at the correct level, bright red, and not have a burnt smell.
   Typical fix: Perform a transmission fluid and filter change. If the fluid is heavily contaminated or contains metal debris, it may indicate a more severe internal transmission failure.
   Est. part cost: $100-$250

Rare But Worth Checking

• Wiring Harness Issue: Damage to the wiring between the TCM and the transmission can cause communication errors or shorts, mimicking a component failure. This is worth inspecting before replacing expensive components, though the TSB for this platform makes it a less likely culprit for this specific symptom. A loose ground connection at G110 or G114 has been noted as a potential issue on these trucks.

Diagnosis Steps

1. Verify the presence of code P2724 with an OBD-II scanner. Check for other related codes like P2727 and P2729.
2. Check for any open recalls or Technical Service Bulletins (TSBs) for the vehicle's VIN. Specifically, reference TSB #23-NA-018 (which supersedes #PIP5646D) and Customer Satisfaction Program #N192272400.
3. DO NOT clear DTCs, as instructed by the TSB.
4. Confirm the primary symptom: rear wheels locking up at low speed after a hot soak. The TSB describes two scenarios: after being parked and hot-soaked, or after idling in park for 30 minutes to 4 hours.
5. Based on the TSB, the primary diagnostic path is to condemn and replace the Transmission Control Module (TCM).
6. If the TSB did not exist, a technician would typically check the transmission fluid level and condition, then inspect the wiring harness for damage, and finally test the solenoid itself. However, for this specific vehicle, the TSB provides a direct shortcut to the most likely cause.
7. Follow GM's service information to replace the TCM. This includes programming the new module to the vehicle using the Service Programming System (SPS) and recording the SPS Warranty Claim Code.

Parts You'll Likely Need

• Transmission Control Module (TCM) (OEM #24043411) — This is the part identified by GM in service bulletins as the root cause of the P2724 code and the associated wheel lock-up symptom on these trucks. This part number has been superseded by 24070762. Other service numbers may include 24049790, 24043413, 24289415, and 24296206.
  Trusted brands: ACDelco (OEM)
  OEM price range: $170-$300
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• P2727 — Pressure Control Solenoid 'E' Stuck Off. This code is explicitly mentioned in TSB #23-NA-018 as appearing with the same TCM failure condition.
• P2729 — Pressure Control Solenoid 'E' Control Circuit High. This code is also explicitly mentioned in TSB #23-NA-018 as appearing with the same TCM failure condition.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #PIP5646D / #23-NA-018: Addresses rear wheels locking up at low speeds, noting that DTCs P2724, P2727, or P2729 may be set. It identifies an internal TCM failure as the cause and instructs technicians to replace the TCM with part number 24043411.
• Customer Satisfaction Program #N192272400: A program to replace the TCM at no charge (initially stated to be in effect until May 31, 2022, later extended to June 30, 2022) for this specific wheel lock-up condition due to an internal short circuit.

Platform-Specific Known Issues

• A GM Customer Satisfaction Program (#N192272400) was initiated for 2019-2020 Sierra/Silverado models with the 8-speed automatic transmission for a condition where rear wheels lock up at low speeds due to an intermittent short circuit in the TCM. The program offered free replacement of the TCM until June 30, 2022.
• TSB #PIP5646D and its successor #23-NA-018 provide detailed diagnostic information for dealers, advising them to replace the TCM when P2724, P2727, or P2729 are present with the wheel lock-up symptom. The bulletin specifically mentions the transmission RPO code MQE.

Mechanic-Grade Diagnostic Values

• Pressure Control (PC) Solenoid Resistance — expected: 4.5–5.5 ohms. Failure: A reading significantly outside this range, especially near 0 ohms (short) or infinite (open), indicates a failed solenoid. However, TSB 23-NA-018 advises against this check, pointing directly to TCM failure for the specified symptoms.
• Internal Mode Switch (IMS) Hall-Effect Sensor Voltage — expected: 0.70 to 0.96 Volts (ON) or 1.68 to 2.38 Volts (OFF). Failure: Voltages outside these ranges for a given gear selector position can indicate a fault in the IMS, which communicates gear selection to the TCM.

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Solenoid Valve Characterization Reprogramming — This must be performed after replacing the TCM, valve body, or the entire transmission. It uses the Part Unique Number (PUN) from the valve body or Transmission Unique Number (TUN) from the case to load the correct performance data into the new TCM.
• GDS2 (GM Global Diagnostic System 2): Transmission Service Fast Learn — After programming the new TCM, this procedure must be run to allow the module to learn the individual clutch apply pressures. Failure to do so can result in poor shift quality. The transmission fluid must be between 167°F (75°C) and 185°F (85°C) to run the procedure.
• GDS2 (GM Global Diagnostic System 2): Transmission Adaptive Values Learn — This function is used to perform adaptive learning for specific clutches if a particular shift feels harsh or soft after the Service Fast Learn is complete.

Wiring & Ground Locations

• TCM Location — On 2019+ T1 platform trucks, the TCM is mounted externally, either on the back of the fan shroud or on the firewall behind the fuse panel.. Knowing the location is necessary for visual inspection of the module and its connectors, and for replacement.
• G110 / G114 — Frame grounds on the T1XX platform.. GM has an Engineering Information bulletin (PIE0548) regarding potential loose connections at these grounds on 2019-2020 Sierra/Silverado models, which can cause various electrical issues. While not directly linked to P2724 in the TSB, a poor ground can cause erratic module behavior.
• Block to Chassis Ground — A ground strap running from the engine block to the chassis/firewall. On some GM trucks, a common failure point is the bolt on the back of the block.. A poor main engine/chassis ground can cause a host of electrical problems, including module communication errors and incorrect sensor readings, potentially mimicking a component failure.

Real Owner Repair Stories

• Reddit user comment (2019 Chevy Silverado 2.7L with an 8-speed transmission) — Not specified, but related to transmission issues.
  ❌ Tried (didn't work) Not specified.
  ✅ What actually fixed it The user suggests that a notorious point of failure is the TCM harness itself. The fix involves draining the fluid, dropping the pan, and replacing the harness inside the transmission. If that fails, they point to the valve body.

OEM Part Supersession History

• 24043411 → 24070762 — Standard part evolution for bug fixes or manufacturing process improvements. Part 24043411 is the number explicitly mentioned in TSB 23-NA-018.
• Multiple (24298475, 24296206, 24289415, etc.) → 24043411 — Consolidation of previous part numbers into a single service part.
  Heads up: Part number 24043411 is listed as a replacement for numerous older part numbers.