1. Introduction
This manual provides essential information for the proper installation, operation, and maintenance of your HELLA 007794311 12V 20/40 Amp SPDT RES Relay with Weatherproof Bracket. Please read these instructions thoroughly before use to ensure safe and effective performance.
2. Safety Information
WARNING: Electrical components can cause injury or damage if not handled correctly. Always disconnect the vehicle's battery before performing any electrical work.
- Ensure all wiring connections are secure and properly insulated to prevent short circuits.
- Verify the relay's voltage and current ratings match your application requirements.
- Do not exceed the specified current ratings for the relay.
- Consult a qualified automotive technician if you are unsure about any installation steps.
3. Product Overview
The HELLA 007794311 is a 12V Single Pole Double Throw (SPDT) relay designed for automotive applications. It features a 20/40 Amp rating and includes a weatherproof bracket for enhanced durability in various environments. This relay is commonly used to switch higher current loads using a lower current control signal.
Figure 3.1: Overall view of the HELLA 007794311 relay with its weatherproof bracket.
Figure 3.2: Front view of the relay, displaying the internal schematic and pin numbers (30, 85, 86, 87, 87A).
Figure 3.3: Bottom view of the relay, showing the electrical terminals for connection.
4. Specifications
| Feature | Specification |
|---|---|
| Model Number | 007794311 |
| Brand | HELLA |
| Operating Voltage | 12 Volts DC |
| Current Rating | 20/40 Amps (Normally Closed/Normally Open) |
| Contact Type | SPDT (Single Pole Double Throw) |
| Number of Terminals | 5 |
| Mounting Type | Bracket Mount |
| Connector Type | Solder (for internal connections, external typically uses spade terminals) |
| Dimensions | Approximately 3 x 1.9 x 1.9 inches |
| Weight | Approximately 1.58 ounces |
5. Setup and Installation
5.1. Pin Configuration
The HELLA 007794311 relay uses standard Bosch-style pin numbering:
- Pin 30: Power input from battery (fused).
- Pin 85: Ground connection for the coil.
- Pin 86: 12V trigger input for the coil.
- Pin 87: Normally Open (NO) output. Connects to Pin 30 when the relay is activated.
- Pin 87A: Normally Closed (NC) output. Connects to Pin 30 when the relay is de-activated.
5.2. Wiring Diagram
Refer to the diagram printed on the relay casing (Figure 3.2) for the internal schematic. A typical wiring setup involves:
- Connect Pin 30 to a fused 12V power source (e.g., directly from the battery or a main power distribution point). The fuse should be rated appropriately for the load.
- Connect Pin 85 to a chassis ground.
- Connect Pin 86 to a 12V trigger source (e.g., a switch, another relay's output, or an ignition-switched circuit).
- Connect the positive lead of your accessory/load to Pin 87 (for normally open operation) or Pin 87A (for normally closed operation).
- Connect the negative lead of your accessory/load to a chassis ground.
Note: The weatherproof bracket allows for secure mounting in various locations, protecting the relay from environmental elements. Ensure the mounting location is stable and free from excessive vibration.
6. Operating Instructions
This relay operates as an electrical switch. When 12V power is applied to Pin 86 and Pin 85 is grounded, an electromagnetic coil inside the relay is energized. This causes a mechanical switch to change state:
- When the coil is de-energized (no power to Pin 86), Pin 30 is connected to Pin 87A (Normally Closed).
- When the coil is energized (power to Pin 86), Pin 30 is connected to Pin 87 (Normally Open), and the connection to Pin 87A is broken.
This allows a low-current signal (to Pins 85 and 86) to control a high-current circuit (through Pins 30, 87, or 87A).
7. Maintenance
The HELLA 007794311 relay is designed for long-term, maintenance-free operation. However, periodic checks can help ensure continued reliability:
- Visual Inspection: Periodically inspect the relay and its connections for any signs of corrosion, loose wires, or physical damage.
- Connection Integrity: Ensure all spade terminals or wiring connections remain tight and secure.
- Environmental Protection: Verify the weatherproof bracket and any associated seals are intact to protect the relay from moisture and debris.
No internal user-serviceable parts are present. Do not attempt to disassemble the relay.
8. Troubleshooting
If the relay or the connected circuit is not functioning as expected, consider the following:
| Problem | Possible Cause | Solution |
|---|---|---|
| Relay does not click or activate | No 12V to Pin 86, no ground to Pin 85, or faulty relay coil. | Check voltage at Pin 86 and ground at Pin 85. Test relay coil continuity with a multimeter. Replace relay if coil is open. |
| Accessory/Load does not receive power | No 12V to Pin 30, faulty connection to Pin 87/87A, or blown fuse. | Verify 12V at Pin 30. Check continuity between Pin 30 and the active output pin (87 or 87A) when relay is energized/de-energized. Inspect fuse in the power line to Pin 30. |
| Relay makes clicking sound but load doesn't work | High resistance in load circuit, faulty load, or corroded relay contacts. | Check wiring to the load. Test the load directly. If contacts are suspected, replace the relay. |
| Relay remains activated/deactivated | Stuck contacts or continuous/intermittent power to coil. | Check trigger signal to Pin 86. If signal is correct and relay is stuck, replace the relay. |
9. Warranty and Support
HELLA products are manufactured to high-quality standards. For specific warranty information, please refer to the documentation included with your purchase or visit the official HELLA website. If you require technical assistance or have questions regarding this product, please contact HELLA customer support through their official channels.
For more information and product range, visit the HELLA Brand Store.