WOMS
P code powertrain Medium severity

P0946 Hydraulic Pump Relay Circuit Range/Performance

The OBD2 code P0946 indicates a problem with the hydraulic pump relay circuit, specifically that the performance or range of the circuit is outside the expected parameters, which may affect the operation of the...

Definition

The OBD2 code P0946 indicates a problem with the hydraulic pump relay circuit, specifically that the performance or range of the circuit is outside the expected parameters, which may affect the operation of the hydraulic system

Common causes

  • Faulty hydraulic pump relay
  • Wiring issues (shorts, opens, or corrosion)
  • Poor electrical connections
  • Malfunctioning hydraulic pump
  • Faulty engine control module (ECM)
  • Low hydraulic fluid level
  • Blocked hydraulic lines or filters
  • Faulty pressure sensor or switch

Common misdiagnoses

  • Transmission fluid issues
  • Faulty transmission control module (TCM)
  • Wiring or connector problems
  • Defective hydraulic pump
  • Low battery voltage
  • Faulty relays or fuses
  • Incorrectly calibrated sensors
  • Mechanical transmission issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect the Wiring and Connectors

    Visually inspect the wiring and connectors associated with the hydraulic pump relay. Look for signs of damage, corrosion, or loose connections

  3. 3. Pay special attention to the relay and its associated wiring harness

  4. 4. Test the Hydraulic Pump Relay

    Use a multimeter to test the relay for proper operation. Check for continuity and ensure that it is functioning as intended

  5. 5. If the relay is faulty, replace it with a new one

  6. 6. Check Power and Ground

    Verify that the hydraulic pump relay is receiving the correct voltage and ground signal. Use a multimeter to check the voltage at the relay terminals

  7. 7. If there is no power or ground, trace the circuit back to the source to identify any breaks or shorts

  8. 8. Inspect the Hydraulic Pump

    Check the hydraulic pump itself for any signs of failure or malfunction. Listen for unusual noises or check for leaks

  9. 9. If the pump is not functioning correctly, it may need to be repaired or replaced

  10. 10. Examine the Control Module

    If the relay and pump are functioning correctly, the issue may lie within the vehicle's control module (ECM/PCM). Check for software updates or reprogramming needs

  11. 11. In some cases, a reset of the control module may be necessary

  12. 12. Check Fluid Levels and Condition

    Ensure that the hydraulic fluid levels are adequate and that the fluid is in good condition. Contaminated or low fluid can affect pump performance

  13. 13. Perform a System Test

    If available, use a scan tool to perform a system test or actuator test to see if the hydraulic pump operates correctly when commanded

  14. 14. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P0946 code for your specific vehicle make and model. Manufacturers may have issued guidance or fixes for known issues

  15. 15. Clear Codes and Test Drive

    After performing repairs or replacements, clear the trouble codes and take the vehicle for a test drive to see if the code returns.Conclusion If the issue persists after following these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. They may have access to specialized tools and equipment to pinpoint the problem more accurately