Hydraulic Pump Relay Circuit/Open
The P0945 code indicates a fault in the hydraulic pump relay circuit, typically found in vehicles with electronic stability control or brake assist systems. The powertrain control module (PCM) detects an open or short circuit in the relay control circuit, preventing the hydraulic pump from operating correctly. This can affect brake boost or transmission shift quality, depending on the system.
01. Most Common Causes
- Faulty hydraulic pump relay
- Blown fuse or wiring issues
- Corroded or loose relay connector
02. Symptoms You Will Notice
- Illuminated check engine light
- Reduced brake assist or hard pedal
- Transmission shifting issues (if pump is for transmission)
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0945 is present.
Step 2: Inspect the hydraulic pump relay and its fuse; test for power and ground.
Step 3: Check wiring and connectors for damage, corrosion, or looseness.
Step 4: Replace relay if faulty; clear codes and test drive.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended as it may cause loss of brake assist or transmission function, leading to unsafe driving conditions.
How much does it cost to fix?▼
Typically $50-$150 for relay replacement, but could be higher if wiring repairs are needed.