Hydraulic Pump Relay Circuit/Open
The P0945 code indicates a fault in the hydraulic pump relay circuit, typically found in vehicles with hydraulic brake boost or suspension 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 lead to reduced braking assistance or suspension performance.
1. Symptoms You Will Notice
- Brake warning light illuminated
- Hard brake pedal or increased stopping distance
- Hydraulic pump running continuously or not at all
- Suspension system malfunction (if applicable)
2. Most Common Causes
- Blown fuse for the hydraulic pump relay
- Faulty hydraulic pump relay
- Open or shorted wiring in the relay circuit
- Failed hydraulic pump motor
3. Step-by-Step Diagnosis
Step 1: Check the hydraulic pump relay fuse and replace if blown.
Step 2: Test the relay for proper operation using a multimeter; replace if faulty.
Step 3: Inspect wiring and connectors for damage, corrosion, or loose connections.
Step 4: Verify voltage and ground at the relay socket; repair as needed.
Step 5: If all else is good, test the hydraulic pump motor and replace if defective.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The hydraulic pump may fail, leading to loss of brake assist or suspension control, increasing the risk of an accident.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, but can be higher if the pump motor needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.