Hydraulic Pump Relay Circuit High
The P0948 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the hydraulic pump relay control circuit. This relay is responsible for supplying power to the hydraulic pump, which is used in systems like power steering, brake boost, or transmission control. A high voltage reading suggests a short to power, faulty relay, or wiring issue, potentially causing the pump to run continuously or not at all.
01. Most Common Causes
- Faulty hydraulic pump relay
- Short to power in the relay control circuit
- Damaged wiring or connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Illuminated Check Engine Light
- Hydraulic system malfunction (e.g., hard steering, brake issues)
- Unusual pump noise or continuous operation
- Possible loss of power assist
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0948 is present.
Step 2: Inspect the hydraulic pump relay and its wiring for damage or corrosion.
Step 3: Test relay control circuit voltage with a multimeter; should be within spec.
Step 4: Check for shorts to power by disconnecting relay and measuring voltage at control wire.
Step 5: Replace relay if faulty; repair wiring if short found.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended as it can lead to loss of hydraulic assist, affecting steering or braking, which may compromise safety.
How much does it cost to fix?▼
Typically $50-$150 for relay replacement or wiring repair, but could be higher if PCM replacement is needed.