Fault code P2546 – torque management request input signal “A” low

Fault code P2546 is called “Torque Management Request Input Signal “A” Low” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P2546

This is a general code that is defined as “torque control request, low “A” input signal. Regardless of the actual wording, the presence of code P2546 indicates that the torque control request has failed within the time period set by the manufacturer.

Fault code P2546 – torque management request input signal

Almost all manufacturers use a strategy known as “torque management” in automatic transmissions. To reduce shift harshness as well as extend the life of internal transmission components. This strategy is especially useful in high-powered, high-performance vehicles. In which sudden acceleration can cause serious mechanical damage to the transmission.

Simply put, the system uses inputs from various engine sensors and control modules. Such as the fuel control module, ignition advance, transmission and others. To slow down the ignition advance settings, just before and during gear shifting.

In a fully functional system, this effectively reduces engine torque, which improves feel and gives a smoother shifting experience. In fact, in some vehicles, this system is so advanced that gear shifts are virtually invisible.

The Transmission Control Module (TCM) sends a torque control request to the Powertrain Control Module (PCM) via the CAN bus system. For example, during aggressive acceleration when driving conditions require it. At the same time, the PCM communicates with the TCM to confirm that it has received the torque control request.

However, if any fault or defect occurs during the request and the PCM is unable to execute the request due to this fault, it will inform the TCM that the request has not been executed. After that, the fault code P2546 will be written to memory.

Note that the number of failure cycles required to set the code and illuminate the check lamp depends on the manufacturer. In some cases, the error will be set at the first failure. In other cases, up to eight or more failure cycles must occur before the code is set and the indicator lamp illuminates.

Symptoms of vehicle malfunctions

The main signal that an error P2546 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be recorded in the memory as a fault).
  2. The vehicle enters the transmission emergency mode.
  3. The transmission slips when shifting gears.
  4. Transmission is stuck in gear.
  5. Hard gear shifting.
  6. Engine may stall at idle or low revs.
  7. Increased fuel consumption.
  8. Overall performance may decrease throughout the engine’s operating range.

This error is quite serious, as it can cause problems with the vehicle’s drivability. If code P2546 is not corrected in a timely manner, serious mechanical damage to the transmission may occur.

Factors that can cause this error code

The error code P2546 can mean that one or more of the following problems have occurred:

  • Bad electrical connection of the CAN bus (Controller Area Network).
  • Wiring problem or damaged connector.
  • System driver circuit failure in PCM
  • In some cases, PCM or TCM failure.

How to fix or reset OBD-2 code P2546

Some suggested steps for troubleshooting and fix the error code P2546:

  1. Read all data and error codes stored in the PCM memory with an OBD-II scan tool.
  2. Reset the stored codes and test drive the vehicle.
  3. If the error has returned, check the connectors, and check the wiring for damage or poor contact.
  4. Check the CAN bus electrical connection.
  5. If the code is still active, most likely a firmware or PCM/TCM replacement is required.

Diagnose and repair of problems

Before you begin the process of troubleshooting P2546, you should research the Technical Service Bulletins (TSBs) for your specific vehicle. In some cases, this can save you a lot of time by pointing you in the right direction.

You should then perform a detailed visual inspection to check the wiring condition for obvious defects. Check the connectors and wiring as well as the PCM or TCM.

Normal readings for wiring and connections should be 0 ohms of resistance. The wiring continuity check should always be done with power disconnected from the circuit. To avoid short-circuiting and creating additional damage.

Resistance or lack of continuity indicates faulty wiring that is open or shorted. In this case, repair or replacement will be necessary.

Transmission control module (TCM)

To check if the TCM is actually sending a signal, you will need a graph multimeter set up for duty cycle, or a digital storage oscilloscope. Connect the positive wire of the multimeter, to the wiring harness going to the TCM. And the negative wire to a good ground.

The duty cycle should be the same as the one set by the TCM in the extended readout of the diagnostic tool. If the cycle remains at 0% or 100% or is intermittent, check the connections again. If all wiring is OK, but error P2546 remains, the TCM may be defective.

On which vehicles does this problem occur most frequently

Fault code P2546 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Ford (Focus)
  • Honda (CR-V)
  • Kia
  • Volkswagen

Fault code P2546 can sometimes be found with other errors. The most common are the following: P2544, P2545, P2547, P2548, P2549, P2550, P2551.


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