Fault code P071F – transmission mode switch “B” circuit high

Fault code P071F is called “Transmission Mode Switch “B” Circuit High” 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 P071F

This diagnostic trouble code (DTC) is a generic transmission code. Error P071F is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P071F – transmission mode switch

Modern vehicles have an automatic transmission control module called a transmission control module (TCM). The Powertrain Control Module (PCM) communicates with the TCM. To monitor the automatic transmission for malfunctions.

If your vehicle retains code P071F, it means that the powertrain control module (PCM) has received a data input signal. Which indicates that a problem has been detected that requires the malfunction indicator lamp (MIL) to turn on.

The transmission mode switch activates this fault when the control module detects a high signal level. In this case, the fault relates to the “B” circuit of the transmission mode switch.

Some models may require up to 8 drive cycles with the problem before the malfunction light will illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P071F has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Gear mode switch does not work.
  2. Unstable or abrupt gear shifting.
  3. Takes a long time to shift gears.
  4. Low power under heavy load.
  5. Transmission does not shift into a lower gear when torque is needed.
  6. Transmission may be put into emergency mode.

A stored code P071F indicates that a potentially serious fault has been detected. This can cause you to put unnecessary strain on the transmission and its components.

Factors that can cause this error code

The error code P071F can mean that one or more of the following problems have occurred:

  • Faulty or damaged mode switch.
  • Corrosion of connectors or contacts causing high resistance.
  • Wiring problem, e.g. open or short circuit.
  • Faulty shift lever.
  • Blown fuse or fusible link.
  • Sometimes a faulty PCM or TCM module is the cause.

How to fix or reset OBD-2 code P071F

Some suggested steps for troubleshooting and fix the error code P071F:

  1. Connect an OBD-II scanner to the vehicle’s diagnostic connector, and read all stored data and error codes.
  2. Clear the error codes, perform a test drive, and check if the P071F error appears again.
  3. Visually inspect the electrical wires and connectors.
  4. If necessary, repair or replace any shorted, broken, damaged, or corroded components.
  5. Check the fuse or fusible link.
  6. Inspect the shift lever as well as the mode switch.

Diagnose and repair of problems

The first thing to do when starting to diagnose the P071F fault is to check the electrical part for damage. In today’s vehicles, electrical and electronic signals require good cabling for proper data transmission. Any faults, such as breaks, disconnected connectors, or corrosion, can interrupt signals, leading to transmission control failures.

Check the battery pack, as some PCM and TCM modules are sensitive to low voltage. If the battery is low, the system may detect this as a failure. Make sure the battery is delivering at least 12 volts and that the alternator is running properly, at least 13 volts at idle.

If the car does not show a failure caused by faulty wiring, the problem is most likely caused by the mode switch itself. Its replacement should solve the problem with the P071F error. But don’t overlook fuses either, because a blown fuse is a common problem.

As with any transmission malfunction, always make sure the fluid levels and quality are at the proper level, and keep them in good condition.

On which vehicles does this problem occur most frequently

Fault code P071F can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Buick
  • Chevrolet
  • Dodge
  • Ford
  • GMC
  • Ssangyong (Actyon, Korando, Kyron)

Fault code P071F can sometimes be found with other errors. The most common are the following: P071A, P071B, P071C, P071D, P071E.

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