Fault code P0885 – TCM power relay control circuit/open

Fault code P0885 is called “TCM Power Relay Control Circuit/Open” 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 P0885

If your OBD-II-equipped vehicle has stored code P0885, it means that the PCM has detected an open voltage or undefined condition in the TCM power relay control circuit. The error is accompanied by a lit lamp on the instrument panel.

Fault code P0885 – TCM power relay control circuit/open

In most cases, the TCM module is integrated in a single housing with the PCM. However, the part of the module that controls the automatic transmission function may be powered separately.

The TCM normally receives power only when the ignition switch is on, starting, or in the operating position. This circuit is equipped with a fuse, fusible link, or relay. Often the PCM and TCM receive power from the same relay, although on separate circuits.

The electronic transmission control systems in OBD-II equipped vehicles are controlled by a network of computers called control modules. This involves constant communication between the various control modules via the Controller Area Network (CAN).

Each time the engine is started, the PCM performs a self-test of all controllers. If no normal voltage input signal is detected. Code P0885 will be stored and the malfunction indicator light may illuminate.

On some models, the transmission controller may put the operation into an emergency mode. This means that only 2-3 gears will be available for travel.

Symptoms of vehicle malfunctions

The main signal that an error P0885 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 stored as a fault).
  2. Other related fault codes may also be present.
  3. Sharp or unstable gear shifting.
  4. Delayed gear engagement.
  5. Emergency mode of transmission operation.
  6. Intermittent readings or complete speedometer malfunction.
  7. Electronic traction control system may malfunction.
  8. Disabling the anti-lock braking system (ABS).

Diagnostic fault code P0885 is considered serious because the transmission may operate in emergency mode, making the vehicle barely driveable. For this reason, this error should be corrected as soon as possible.

Factors that can cause this error code

The error code P0885 can mean that one or more of the following problems have occurred:

  • Defective power relay PCM or TCM.
  • Fuse blown.
  • Open or short circuit in CAN circuit.
  • Damaged, corroded wiring or connectors.
  • Faulty vehicle speed sensor.
  • Mechanical failure of transmission.
  • Defective TCM, PCM module or programming error.

How to fix or reset OBD-2 code P0885

Some suggested steps for troubleshooting and fix the error code P0885:

  1. Inspect the wiring for damage, abrasions, breaks, and shorts. If wiring is damaged, repair or replace it.
  2. Remove all diagnostic trouble codes from the PCM, and test drive to see if diagnostic trouble code P0885 returns.
  3. If the code returns, check the TCM, PCM relay to make sure it is working properly.
  4. Inspect and check the fuse and fusible link.
  5. Check the wiring diagram of the relay and fuse system.
  6. Clear the fault codes again and perform a test drive.
  7. Insert the key into the ignition switch and turn it to the on position. If the Check Engine light does not come on, but the code in memory comes back on, the relay may be faulty.
  8. If the relay is faulty, you may need to replace and reprogram the TCM, PCM.

Diagnose and repair of problems

To exclude all variants of error P0885, you should visually inspect the wiring, check the voltage on the battery. Also check the battery terminals and cables for loose connections.

Ensure that the system voltage is as specified in the manual. The charging system is fully functional, and the battery is in good condition, begin the diagnostic procedure.

Locate the starting point of the TCM power circuit. This is usually the ignition switch, so use a digital multimeter to check the voltage at this wire or terminal. Compare the reading with the value given in the manual, and repair if necessary if an abnormality is found.

If the code remains, but the power supply to and from the ignition switch is within the specified range. Note and test the power supply to the fuse box and then to the TCM connector. If any abnormalities are found, make the necessary repairs. To ensure that all electrical parameters are in accordance with the manufacturer’s specifications.

The steps described above will help eliminate error P0885, but in some cases where the cause is not obvious, intermittent faults may be present. Also, if the TCM is already damaged it may need to be repaired by a specialized repair shop.

On which vehicles does this problem occur most frequently

Fault code P0885 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Chrysler
  • Dodge
  • Ford
  • Hyundai (Santa Fe, Sonata, Tiburon, Tucson)
  • Jeep
  • Kia (Carens, Sportage)
  • Peugeot (107)
  • Smart
  • Toyota (Corolla, Yaris)

Fault code P0885 can sometimes be found with other errors. The most common are the following: P0880, P0881, P0882, P0883, P0884, P0886, P0887, P0888, P0889, P0890, P0891, P0892.

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