Hydraulic Pump Relay Circuit Malfunction
The C1936 code indicates an electrical fault in the relay circuit that controls the hydraulic pump. The control module monitors the integrity of the relay activation and deactivation circuit and has detected an abnormal condition such as an open circuit, short to ground, short to voltage, or excessive resistance. This relay supplies power to the hydraulic pump, which is typically part of air suspension, chassis leveling, or electro-hydraulic power steering systems, depending on the vehicle platform.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty hydraulic pump relay with burned or corroded contacts
- Open circuit, short to ground, or short to voltage in the relay wiring
- Corroded, loose, or damaged relay connector or pins
- Blown fuse in the hydraulic pump power supply circuit
- Hydraulic pump mechanical failure or overcurrent affecting the control circuit
- Faulty control module not supplying the activation signal to the relay
3. Symptoms You Will Notice
- Hydraulic pump inoperative or intermittent operation
- Suspension or steering system warning light illuminated
- Vehicle ride height or handling issues
- Noisy or non-functioning hydraulic pump
4. Step-by-Step Diagnosis
Check and test the hydraulic pump relay and its control circuit for opens, shorts, or high resistance
Inspect the relay connector and pins for corrosion or damage
Verify the fuse for the hydraulic pump power supply is intact
Test the hydraulic pump for mechanical binding or excessive current draw
If all else is normal, diagnose the control module for proper relay activation signal
5. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive. The hydraulic pump may fail completely, leading to loss of suspension or steering assist, which can cause a serious accident.
How much does it cost to fix?▼
The repair cost typically ranges from $150 to $600, depending on the root cause. A relay replacement is on the lower end, while a control module or pump replacement can be higher.