The hydraulic pump relay is vital for the transmission pump’s operation, so an abnormally high voltage reading often indicates an electrical issue somewhere along the circuit. In this scenario, the ECU records a DTC P0948.
How severe is the code?
Diagnostic code P0948 is very serious, as it indicates the likelihood of an electrical problem along the hydraulic pump circuit. This can lead to a number of driving issues, which may result in very serious/costly repairs if not diagnosed.
Symptoms
Symptoms of a P0948 include:
- Harsh shifts
- Slipping
- Failed shifts
Causes
- Transmission fluid is too low or too dirty
- Damaged wiring
- Corroded or broken connectors
- Hydraulic pump relay failure
- ECU or TCM issues
How to diagnose the code?
The diagnostic process for an OBDII fault code P0948 obviously involves checking the transmission pump relay. But the level and condition of the transmission fluid, as well as the state of the wiring and connectors along the transmission wiring harness, can also trigger this OBD2 code.
What repairs will fix P0948?
- Change the transmission fluid/filter
- Repair or replace damaged wiring and/or connectors
- Replace the hydraulic pump relay
- Reprogram or replace the ECU/TCM