P0737 - TCM (Transmission Control Module) Engine Speed Output Circuit

Introduction

The DTC P0737 trouble code represents a problem with the engine speed output circuit within the transmission control module (TCM). This code indicates that the TCM has detected a discrepancy in engine speed readings, which can negatively affect the vehicle's performance and ability to shift gears efficiently. Understanding the causes, symptoms, and solutions for this error is critical for every auto mechanic.

Symptoms

Symptoms associated with the DTC code P0737 may vary depending on the vehicle and operating conditions, but commonly include:

  • Transmission slippage :
    the car may have difficulty holding a gear or shifting gears smoothly.

  • Erratic engine revolutions :
    the engine may behave erratically, with oscillation in revolutions per minute (RPM).

  • Warning light comes on :
    the check engine light comes on on the dashboard.

  • Performance decrease :
    The vehicle may have reduced power or respond slowly to acceleration.

  • Transmission problems :
    difficulty shifting gears, especially under high load conditions.

Cause

The DTC code P0737 can be caused by a variety of factors, including:

  • Electrical problems :
    Damaged wires, corrupted connectors, or breaks in the TCM circuit can affect speed readings.

  • TCM failure :
    A faulty transmission control unit may give incorrect readings or not function properly.

  • Faulty speed sensor :
    The driveshaft or engine speed sensor may be faulty, causing incorrect readings.

  • Contaminated or low transmission fluids :
    Dirty or insufficient transmission fluid can affect the operation of the transmission.

  • Mechanical problems :
    Worn gears or malfunctions in the transmission itself can cause incorrect readings.

Diagnosis

To diagnose the P0737 error code, follow these steps:

  1. Vehicle Scan :
    use an OBD-II diagnostic tool to scan the vehicle and confirm the presence of the DTC code P0737.

  2. Check related codes :
    Check for other DTC codes that may provide further information about the problem, such as P0720 (Propel Shaft Speed Sensor), P0715 (Transmission Fluid Temperature Sensor), and P0740 (Transmission Clutch Control Circuit).

  3. Visual inspection :
    inspect the TCM wires and connectors for signs of damage or corrosion.

  4. Sensor Test :
    Check the operation of the driveshaft speed sensor using a multimeter.

  5. Checking the level and quality of the transmission fluid :
    make sure the fluid is level and in good condition.

  6. TCM Test :
    If necessary, perform a test of the transmission control unit to verify that it is functioning correctly.

Resolution and repair

To resolve the DTC code P0737 problem, the following actions can be taken:

  • Cable and connector repair :
    replace or repair any damaged cables or corrupted connectors.

  • Replacing the speed sensor :
    If the speed sensor is faulty, replace it.

  • Replacing the TCM :
    If the transmission control unit is faulty and cannot be repaired, the unit may need to be replaced.

  • Changing the transmission fluid :
    If the fluid is contaminated or low, perform a fluid change and transmission system check.

  • Mechanical transmission check :
    If there are mechanical problems, such as worn gears, the required repairs need to be made.

Insight: Components Involved

For a deeper understanding of the DTC code P0737, it is helpful to examine the components involved:

  • Transmission Control Module (TCM) :
    is responsible for managing gear shifting operations. Its correct function is essential for optimal power transfer.

  • Engine speed sensor :
    provides engine speed information to the TCM, allowing for appropriate gear adjustment.

  • Electrical circuit :
    Proper circuit operation is critical; any interruption or short circuit can affect the readings and, consequently, the performance of the vehicle.

  • Transmission Fluids :
    Fluid quality and level are critical to the operation of the transmission. Dirty or insufficient fluid can cause overheating and malfunction.

Conclusions

DTC P0737 trouble code is a serious problem that can affect vehicle performance and driving safety. Timely diagnosis and resolution of the problem is essential to ensure that the vehicle operates efficiently. Following the diagnosis and resolution steps described in this article can help auto repairers quickly identify and resolve the problem, thus ensuring customer satisfaction and road safety.

Important
Not all OBD2 codes used by one manufacturer are used by other brands, and may not have the same meaning.
The information presented here is for informational purposes only. We are not responsible for any actions you take on your vehicle. If you have any concerns about repairing your vehicle, please contact your repair shop.