The hydraulic pump relay is vital to the operation of the transmission pump, so an abnormally high voltage reading often indicates an electrical problem somewhere along the circuit. In this scenario, the ECU will save a P0948 DTC.
How Serious is the Code?
The P0948 diagnostic trouble code is very serious, because it indicates the likelihood of an electrical problem along the hydraulic pump circuit. This can lead to a number of drivability problems, which can result in very serious/expensive repairs if left undiagnosed.
Symptoms of a P0948 include:
- Rough shifts
- Failed shifts
- Transmission fluid is either 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 process of diagnosing a P0948 OBDII trouble code obviously involves checking the transmission pump relay. But the level and condition of the transmission fluid, as well is the condition of the wiring and connectors along the transmission wiring harness can also cause this OBD2 code.
What Repairs Will Fix P0948?
- Change transmission fluid/filter
- Repair or replace damaged wiring and/or connectors
- Replace hydraulic pump relay
- Reprogram or replace ECU/TCM