If you own or lease a 2019 GMC Acadia, you may have encountered a frustrating problem with your vehicle: the shift to park defect.
This defect prevents drivers from turning off and locking their vehicles, even when they have shifted into park.
This can cause safety risks, battery drain, and inconvenience for drivers who are stuck in their vehicles.
In this article, we will explain what the shift to park defect is, how it affects 2019 GMC Acadia owners, and what you can do if you are experiencing this issue.
We will also discuss the legal actions that have been taken against General Motors (GM), the manufacturer of the 2019 GMC Acadia, for failing to address this defect properly.
Related Post: What Are The Years Of GMC Acadia To Avoid?
What Is The Shift To Park Defect And How Does It Affect 2019 GMC Acadia Owners?
The shift-to-park defect is a problem with the shift interlock solenoid, which is a device that prevents the shifter from moving out of the park unless the brake pedal is pressed. This solenoid is connected to a micro switch that detects the position of the shifter.
When the shifter is in the park, the micro switch sends a signal to the vehicle’s computer, which then allows the driver to turn off and lock the vehicle. However, due to a design flaw, the micro switch can be over-stressed and fail to send the correct signal, even when the shifter is in park.
This results in a message on the dashboard that says “Shift to Park” and prevents the driver from turning off and locking the vehicle. This defect affects many 2019 GMC Acadia owners, as well as owners of other GM and Chevrolet models, such as the Malibu, Traverse, and Volt.
What Causes Shift Malfunction?
Low or old transmission fluid
Low or old transmission fluid, can affect the hydraulic pressure and the lubrication of the transmission components. Low transmission fluid can reduce the hydraulic pressure in the system.
This can cause the transmission to struggle to hold the car in a certain gear and to slip back into another gear. It can also cause delayed or erratic shifting, as the transmission cannot respond to the driver’s input or the driving conditions properly.
Low transmission fluid can also cause the transmission to overheat, as there is not enough fluid to dissipate the heat generated by the friction and the movement of the parts. Overheating can damage the transmission components and lead to failure.
Old transmission fluid can lose its viscosity and its lubricating properties. This can cause increased wear and tear on the transmission parts, as they are not protected from friction and corrosion.
Old transmission fluid can also become contaminated with dirt, debris, or metal shavings, which can clog the valves, the filters, or the solenoids. This can affect the fluid flow and the pressure in the system, which can result in poor shifting performance and transmission damage.
Faulty shift solenoid
Faulty shift solenoid, which is a device that regulates the flow of fluid to the clutch packs and changes the gears. A shift solenoid can become stuck, shorted, or damaged by fluid contamination.
A faulty shift solenoid can cause various transmission problems, such as hard shifting, stuck in gear, rough shifting, or other shifting issues. A shift solenoid can become faulty due to several reasons, such as:
- A stuck plunger is the part of the solenoid that moves when it receives a signal from the TCU. It opens or closes a valve that allows or blocks the fluid flow to the clutch packs. If the plunger becomes stuck due to fluid contamination, wear, or damage, it will not move as intended. This will result in a failure to shift to the desired gear, or a shift to the wrong gear. A stuck plunger can also cause a shift solenoid to remain on or off, which can affect the transmission pressure and the shifting performance.
- A shorted coil winding is the part of the solenoid that creates a magnetic field when it receives a signal from the TCU. The magnetic field moves the plunger and the valve to control the fluid flow. If the coil winding is shorted out due to a broken wire, a loose connection, or a voltage surge, it will not create a magnetic field. This will result in a loss of signal to the solenoid, which will prevent it from operating. A shorted coil winding can also cause a shift solenoid to draw too much current, which can damage the TCU or the fuse.
A malfunctioning input or output speed sensor
A malfunctioning input or output speed sensor is a device that measures the rotational speed of the input and output shafts of the transmission. These sensors provide information to the TCU, which adjusts the shift timing and pressure.
If the input or output speed sensor is malfunctioning, it will send incorrect or erratic signals to the TCU. This will cause the TCU to miscalculate the optimal shift point, which can lead to delayed, harsh, or erratic shifting.
Malfunctioning input or output speed sensors are devices that measure the rotational speed of the input and output shafts of the transmission. These sensors provide information to the transmission control unit (TCU), which adjusts the shift timing and pressure.
Malfunctioning input or output speed sensors can cause various transmission problems, such as delayed, harsh, or erratic shifting.
This is because the TCU receives incorrect or erratic signals from the sensors, which affects its ability to control the transmission. For example, if the input speed sensor is faulty, the TCU may not detect the engine speed correctly, which can result in shifting too early or too late.
If the output speed sensor is faulty, the TCU may not detect the vehicle speed correctly, which can result in shifting too fast or too slow.
Also Read: What Are The 2019 GMC Acadia Denali Recalls?
Some of the symptoms of a malfunctioning input or output speed sensor are:
- Check the engine light or transmission warning light on the dashboard
- Inaccurate speedometer reading
- Poor fuel economy
- Loss of power or acceleration
- Transmission slipping, shuddering, or jerking
- Transmission stuck in a certain gear or unable to shift
Defective electronic pressure regulator
A defective electronic pressure regulator, is a device that controls the hydraulic pressure in the transmission according to the TCU commands. A faulty regulator can cause erratic or incorrect pressure, which can affect the shifting performance.
A defective EPR can cause erratic or incorrect pressure, which can affect the shifting performance. This can result in delayed, harsh, or erratic shifting, as the clutch packs cannot engage or disengage properly. A defective EPR can also cause the transmission to overheat, slip, or shudder, which can damage the transmission components and lead to failure. Some of the possible causes of a defective EPR are:
- A faulty solenoid valve can become stuck, shorted, or damaged by fluid contamination. This can prevent the EPR from opening or closing as intended, or cause it to draw too much current and damage the TCU or the fuse.
- A faulty TCU can send incorrect or erratic signals to the EPR. This can cause the EPR to regulate the pressure incorrectly, or not at all. A faulty TCU can also affect other transmission functions, such as the shift solenoids and the speed sensors.
- A faulty pressure sensor can measure the output pressure of the EPR incorrectly. This can cause the TCU to receive inaccurate feedback and adjust the EPR incorrectly. A faulty pressure sensor can also trigger a warning light or a trouble code on the dashboard.
Bad transmission pump
Bad transmission pump, which is a device that generates the hydraulic pressure for the transmission. A worn or damaged pump can cause low or inconsistent pressure, which can lead to delayed or harsh shifting.
A worn or damaged pump can cause low or inconsistent pressure, which can lead to delayed or harsh shifting. This is because the pump cannot provide enough fluid or pressure to the clutch packs, which are the components that change the gears.
If the clutch packs cannot engage or disengage properly, the transmission will not shift smoothly or correctly. Low or inconsistent pressure can also cause the transmission to overheat, slip, or shudder, which can damage the transmission components and lead to failure.
Some of the symptoms of a bad transmission pump are:
-
Delayed vehicle response
When you step on the gas, your car should immediately start to move forward. If it takes a moment or two for your vehicle to get going, this could be a sign that your transmission pump is failing. That delay is because the pump is not circulating enough transmission fluid to help change the gears smoothly.
-
Transmission noise
A bad transmission pump can make a loud whining or humming noise when the engine is running. This is because the pump is struggling to generate enough pressure or fluid flow, or because the pump is damaged and rubbing against other parts.
-
Gears slipping
A bad transmission pump can cause the transmission to slip out of gear or skip gears. This is because the pump cannot provide enough pressure or fluid to the clutch packs, which causes them to lose grip or synchronization.
-
Transmission fluid leaks
A bad transmission pump can cause the transmission fluid to leak from the pump seal or the pump housing. This can reduce the fluid level and the pressure in the system, which can affect the shifting performance and the transmission health.
How To Fix The Shift To Park Issue In Your 2019 GMC Acadia?
There are several ways to fix the shift-to-park issue in your 2019 GMC Acadia, depending on the severity of the problem and your level of technical skill.
The simplest way is to try to wiggle and move the shifter back and forth until the message goes away and the vehicle recognizes that it is in the park. This may work temporarily, but the problem will likely recur.
Another way is to replace the shift interlock solenoid and the micro switch, which are the parts that are responsible for the defect. This can be done by a professional mechanic or by yourself if you have the tools and the instructions.
A third way is to modify the micro switch lever to reduce the stress and the travel that causes the switch to fail. This can be done by bending the lever slightly or adding a small wire jumper to the switch. This is a simple and cheap fix that may prevent the problem from happening again.
What Are The Legal Actions Taken Against GM for The Shift To Park Defect?
Many owners and lessees of GM and Chevrolet vehicles have filed lawsuits against GM for the shift to park defect, alleging that the automaker knew about the problem for several years and failed to address it properly.
They claim that the defect poses safety risks, such as the vehicle rolling away or being stolen, and causes battery drain, which leaves them stranded. They also claim that the defect reduces the value and the performance of their vehicles. They seek compensation for the damages and the costs of repairing or replacing their vehicles.
Some of the lawsuits have been consolidated into a class action lawsuit, which is still pending in the court. GM has issued several technical service bulletins (TSBs) to its dealers, instructing them on how to diagnose and fix the problem.
However, these TSBs are not recalls and do not obligate GM to provide free repairs or replacements to the affected customers. GM has also denied any liability or wrongdoing in the lawsuits and has argued that the defect does not pose a safety risk or a breach of warranty.
How To Avoid Potential Safety Risks And Battery Drain Caused By The Shift To Park Issue?
Always apply the parking brake when parking your vehicle, especially on slopes or uneven surfaces. This will prevent the vehicle from rolling away if the shift-to-park defect occurs.
Do not leave your vehicle unattended or unlocked when the shift to park message is displayed. This will reduce the risk of theft or unauthorized access to your vehicle.
Try to wiggle and move the shifter back and forth until the message goes away and the vehicle recognizes that it is in the park. This may work temporarily, but the problem will likely recur.
If you cannot turn off your vehicle due to the shift to park defect, disconnect the negative battery terminal to prevent battery drain. However, this may also affect other electronic systems in your vehicle, such as the radio, clock, or alarm. You may need to reconnect the battery and reset these systems later.
What Are The Other Models And Years Affected By The Shift To Park Defect?
The models and years affected by the shift to park defect include:
- 2016-2019 Chevrolet Malibu
- 2016-2019 Chevrolet Volt
- 2018-2019 Chevrolet Traverse
- 2019 Chevrolet Blazer
- 2017-2018 GMC Acadia
- 2009 and 2014 GMC Acadia (recalled for violating Federal Motor Vehicles Safety Standards)
What Is The Cost To Fix (shift to park) On the 2019 GMC Acadia?
The cost of replacing the shifter assembly at a dealership ranges from $300 to $500, while the cost of replacing or modifying the micro switch only ranges from $10 to $50.
Conclusion
The shift to park defect is a common and frustrating problem that affects many GMC Acadia owners, as well as owners of other GM and Chevrolet models.
We hope this article has offered you helpful tips!
