2011-2013 Regal & 2011 Saab 9-5 TCM: Decoding Shifting Problems & Programming
This guide covers the common failures, diagnostic codes, and mandatory programming requirements for the Transmission Control Module in the Buick Regal and Saab 9-5.
- This module is located INSIDE the transmission and MUST be programmed to your car's VIN to function.
- Symptoms almost always involve severe shifting problems like harsh shifts, getting stuck in gear, or failing to move.
- A used module is a viable option, but you must match the part number and have a programming plan before buying.
- Before replacing the TCM, ask a shop to check for any available software updates, as a simple re-flash can sometimes fix minor shifting issues.
Critical Warning: Programming is Not Optional
Warning: This Transmission Control Module (TCM) absolutely must be programmed to your vehicle's specific Vehicle Identification Number (VIN) after installation. Without programming, the vehicle will not start or run correctly. This is not a plug-and-play part. You must arrange for programming by a GM dealer, a qualified independent shop with GM diagnostic tools (like a Tech 2 or MDI), or a mail-in programming service before you begin the replacement.
Symptoms of a Failing TCM
A failing TCM in a 2011-2013 Buick Regal or 2011 Saab 9-5 will cause significant and noticeable transmission problems. Because the module controls all shifting behavior, its failure can mimic mechanical transmission damage. Look for these common signs:
- Harsh or Delayed Shifting: You may feel a significant bang, clunk, or jolt when the transmission shifts gears. Shifts may also be noticeably delayed, with the engine revving high before the next gear engages.
- Erratic and Unpredictable Shifting: The transmission may downshift or upshift randomly while driving at a steady speed. It can feel confused, hunting for the correct gear.
- Stuck in One Gear (Limp Mode): The transmission may get stuck in a single gear (often 2nd or 3rd) to prevent further damage. This is a self-preservation mode, and the vehicle will have very limited power and speed.
- Complete Loss of Engagement: In some cases, the transmission may fail to engage any gear, acting as if it's in neutral even when Drive or Reverse is selected. This can happen intermittently, sometimes working for a few moments after a restart before failing again.
- Check Engine Light: A failing TCM will almost always trigger the Check Engine Light or other malfunction indicators on the dash.
Common Diagnostic Trouble Codes (DTCs)
A professional scan tool that can read transmission-specific codes is necessary for proper diagnosis. Generic code readers may only show a generic `P0700` (Transmission Control System Malfunction), which simply means the TCM has stored its own codes. Key codes pointing to a faulty TCM include:
- U0101: Lost Communication with TCM.
- P0613: TCM Processor Failure.
- P0776: Pressure Control Solenoid 'B' Performance.
- P0722: Output Speed Sensor Circuit No Signal.
- P0730: Incorrect Gear Ratio.
- P0741: Torque Converter Clutch Circuit Performance or Stuck Off.
- Multiple solenoid performance codes logged at once often point to a failure in the TCM's driver circuits rather than individual solenoids.
Known Issues, Recalls, and Service Bulletins
While there are no direct recalls for the TCM itself, several related service documents exist for these vehicles.
2011-2013 Buick Regal
- Recall 50490 / 50491: This safety recall affects some 2011 Regals and involves a defective electronic park lock lever. It can allow the ignition key to be removed when the transmission is not in Park, creating a rollaway risk. While not a TCM failure, it is a critical transmission-related safety issue to be aware of.
- TSB for Harsh Shifting: For early models with the Gen 1 control system, GM issued a technical service bulletin for harsh or flaring shifts, especially when the transmission is cold. The fix is a TCM software calibration update, which must be performed by a dealer or qualified shop. This should be attempted before replacing the module for this specific symptom.
- Special Coverage 12313: This applies only to 2011 Regals with the 2.4L engine and covers a wearing balance chain. It is an engine issue, not a transmission issue, but is relevant for owners of that specific model year and engine.
2011 Saab 9-5
- There are no major recalls specifically for the transmission or TCM on the 2011 Saab 9-5 in the US market.
- TSB #090730018C: This bulletin provides updated information for dealers regarding claim submission for automatic transmission repairs but does not detail a specific component failure.
Buying a Used Transmission Control Module
A used OEM module is an excellent, cost-effective alternative to an expensive new unit, but you must be careful to ensure compatibility and plan for programming.
- Match Part Numbers Exactly: The most critical step is to match the OEM part number from your original module to the one you are buying. The primary GM part number is 55574324 (which supersedes 55574325). The Saab part number is 55578552. While these are interchangeable, it is always safest to match your original number.
- Verify the Source: Purchase from a reputable seller who tests their electronic modules. Ask about the donor vehicle's mileage if possible. A module from a low-mileage vehicle is always preferable.
- Plan for Programming BEFORE You Buy: Do not purchase a used TCM until you have confirmed how you will get it programmed. Call your local GM dealer or a trusted independent transmission shop. Ask them if they are willing and able to program a customer-supplied used module and what the cost will be. Some will only program parts they sell.
- Inspect for Physical Damage: Although the module is located inside the transmission, it can be damaged during removal or shipping. Check that all connectors are intact and that there are no cracks in the plastic housing.
Cost of Replacement
The cost can vary significantly based on the parts source and labor rates in your area. Because the module is inside the transmission, labor is a larger factor than with externally mounted modules.
| Part/Service | Estimated Cost |
|---|---|
| New OEM (GM/Saab) | $520 - $1,050 |
| New Aftermarket (Dorman) | $700 - $800 |
| Used OEM | $150 - $300 |
| Shop Labor (Replacement & Fluid) | $250 - $500 |
| Programming Service | $100 - $250 |
| Total Estimated Cost | $500 - $1,800 |
Frequently Asked Questions (FAQ)
Can I replace this TCM myself?
This is an advanced DIY job. The TCM is part of the TEHCM assembly located inside the transmission oil pan, attached to the valve body. The job requires draining the transmission fluid, removing the pan, disconnecting and removing the TEHCM, and then performing the process in reverse with the new unit, including a new gasket and filter. Due to the complexity and the absolute requirement for professional programming, this repair is best left to experienced technicians.
Can I drive my car with a bad TCM?
It is strongly advised not to. Symptoms can be unpredictable, including sudden loss of power, getting stuck in gear, or failing to move from a stop. This makes the vehicle unreliable and potentially unsafe to drive. If the transmission enters 'limp mode,' you may be able to drive slowly to a repair shop, but continued driving can cause further damage.
Does the replacement TCM need to be from the exact same vehicle?
No, but the part number must match. A module with part number 55574324 could come from a Buick Regal, Saab 9-5, or even another GM vehicle like a Chevrolet Cruze that uses the same 6T40/6T45 transmission. The key is that the hardware is identical. The vehicle-specific functionality is loaded during the VIN programming process.
What's the difference between the TCM, TCU, and TEHCM?
TCM (Transmission Control Module) and TCU (Transmission Control Unit) are interchangeable terms for the transmission's computer. TEHCM stands for Transmission Electro-Hydraulic Control Module. For these vehicles, the TEHCM is the actual part you replace; it is an assembly that includes the TCM, the transmission solenoids, and pressure switches all in one unit mounted to the valve body.
Technical Specifications
OEM Part Numbers: 55574324 55574325 55578552 55580695 55585102
Integrated Transmission Electro-Hydraulic Control Module (TEHCM) for GM 6T40/6T45 (Gen 1) 6-speed automatic transmissions.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Buick Regal:
- Saab 9-5:
- 🛍️ Shop This Part
- Critical Warning: Programming is Not Optional
- Symptoms of a Failing TCM
- Common Diagnostic Trouble Codes (DTCs)
- Known Issues, Recalls, and Service Bulletins
- 2011-2013 Buick Regal
- 2011 Saab 9-5
- Buying a Used Transmission Control Module
- Cost of Replacement
- Frequently Asked Questions (FAQ)
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