BOLEC EA101 · THREE ALARM CHANNELS
3 Gauge Adjustable Alarm Module
Add an adjustable warning output to your existing engine gauges. The EA101 monitors three compatible resistive sender circuits and activates the corresponding alarm output when a preset fault level is reached.
Low engine oil pressure · High engine temperature · Low gearbox oil pressure
For compatible resistance-to-ground senders with a variable DC signal. Alarm points must be set for your application.
Before you buy — important checks
- Check the sender signal. The sensing unit must be a variable resistance to ground, and the measured signal must be a variable DC voltage. Brand alone does not establish compatibility; some input or output arrangements may not suit the EA101.
- Check 24 V use before ordering. The module label and instruction heading state 12/24 VDC, but the electrical specification in the supplied instructions states 12–14.2 VDC. Ask Bolec to confirm the correct supply rating for the unit and your installation.
- Outputs switch to ground. These are transistor outputs, rated at a maximum of 0.25 A per output for a resistive load. Match the alarm device and its protection to the circuit.
- It requires a working supply and sensing circuit. The instructions warn that the unit will not work if its supply, sender or gauge (where fitted) fails. Do not rely on it to detect every possible system failure.
An alarm output does not automatically stop the engine
The EA101 activates a connected lamp, buzzer or suitably rated relay circuit. Any engine shutdown function needs a separate, correctly designed control circuit.
3 channels
Separate LOP, HET and LGBP inputs and alarm outputs.
Fine adjustment
Three 25-turn potentiometers allow individual alarm-point adjustment.
Existing gauges
Connect alongside compatible gauge sender terminals.
Compact module
Approximately 58 × 42 × 29 mm overall.
Typical engine alarm applications
LOP · Low oil pressure
Set an alarm point for falling engine oil pressure.
HET · High temperature
Set an alarm point for rising engine temperature.
LGBP · Low gearbox pressure
Set an alarm point for falling gearbox oil pressure.
A typical use is early warning on a diesel engine. Standard resistance gauges such as suitable VDO systems are examples; confirm the actual gauge and sender combination before installation.
EA101 product video
Watch the EA101 overview, then use the wiring and setup information below to check your application.
How the EA101 works
1. Monitor the sender signal
The EA101 connects to the sender terminal on each existing gauge and monitors its DC signal.
2. Set the fault level
Use the corresponding adjustment pot to set the warning point shown on the gauge.
3. Activate the alarm
When the fault level is reached, the corresponding transistor output connects the alarm load to ground.
Keep the existing gauge wiring in place
The instructions specify a piggyback connection to each gauge sender terminal. The EA101 adds alarm monitoring alongside the existing circuit; installation does not require rerouting the gauge signal through the module.
Wiring and terminal connections
The drawing shows the HET channel. Repeat the corresponding connections for LOP and LGBP. The drawing is a 12 V example; confirm supply and load suitability before applying it to a 24 V system.
| Terminal | Connection |
|---|---|
| + / IGN+ | Ignition-switched positive supply. The instructions recommend a 0.5 A fuse for the module supply. |
| − / Ground | Connect to a good negative-ground / earth connection. |
| SNDRS · LOP | Connect to the engine oil-pressure sender terminal on its gauge. |
| SNDRS · HET | Connect to the engine-temperature sender terminal on its gauge. |
| SNDRS · LGBP | Connect to the gearbox oil-pressure sender terminal on its gauge. |
| ALARMS · LOP / HET / LGBP | Connect each output to the negative side of its lamp, buzzer or suitable relay coil. The load’s positive side connects to an appropriately fused supply. Each output switches internally to ground on a fault. |
Maximum 0.25 A per output — resistive load
The wiring drawing labels the lamp/buzzer “Max 3.5 Watt”, while the written specification rates each output at 0.25 A. Use the 0.25 A per-output limit when selecting the load, rather than treating 3.5 W as a universal rating. For example, 0.25 A at 12 V is 3 W.
Protect the lamp, buzzer or relay circuit with an appropriate fuse as well as protecting the module supply. The instructions recommend reverse-EMF suppression diodes across relay and solenoid coils. Confirm suitability for inductive loads; the stated current rating is for resistive loads.
Can it work without gauges?
Yes — the instructions allow sender-only operation. The wiring diagram specifies a 1 kΩ, 1 W resistor at the marked position when no gauge is fitted.
The illustrated arrangement is a 12 V HET example. Confirm the sender, supply voltage, resistor arrangement and method of setting the alarm threshold with Bolec before using a sender-only installation. The gauge-pointer calibration method below assumes that a gauge is fitted.
Setting the alarm points
Set each channel individually using an appropriate variable resistance in place of its sender. The instructions give typical test ranges of 0–300 Ω or 0–500 Ω; select a range suitable for your gauge and sender.
1. Check the wiring
Check all connections and look for possible short circuits before applying power.
2. Substitute the sender
Temporarily replace the relevant gauge sender with a suitable variable resistance or gauge-check instrument.
3. Choose the warning point
Switch on the ignition and adjust the test resistance until the gauge pointer shows your required alarm reading.
4. Adjust the EA101 pot
Turn the corresponding pot anticlockwise until its LED is off. Then turn it slowly clockwise until the LED just comes on.
5. Verify the threshold
Move the test resistance above and below the setting several times. Fine-tune the switch point and check the connected alarm.
6. Restore and check
Repeat for the other channels. After setup, remove the test resistance, reconnect the actual senders and verify the installed system.
Each adjustment pot has 25 turns. The instructions state that turning past either end will not harm the pot. A test light can simplify setup by temporarily replacing the alarm circuit.
Choose alarm points for the actual engine or gearbox
No universal oil-pressure or temperature setting is specified. Use the equipment’s required operating limits and verify each alarm channel after adjustment.
Installation notes and limitations
- Mount near the instruments or fuse panel. The instructions allow 3/16-inch or 5 mm screws, double-sided tape or silicone. Mounting orientation is not critical.
- Confirm compatibility before fitting. The module is intended to suit many automotive gauge systems, but some input or output signals may be incompatible.
- Check alarm operation as part of system maintenance. The module depends on a working supply and sensing circuit. Where practical, the instructions recommend fail-safe circuit design.
- Use the complete connection instructions for installation. The information here explains product selection, wiring and setup; seek Bolec’s advice if the system differs from the illustrated arrangement.
Technical specifications
| Item | Specification |
|---|---|
| Model | EA101 — 3 gauge adjustable alarm |
| Alarm channels | LOP: low oil pressure; HET: high engine temperature; LGBP: low gearbox pressure |
| Sender / input type | Variable resistance to ground; measured signal must be variable DC voltage |
| Supply voltage | Label and instruction heading: 12/24 VDC. Electrical specification: 12–14.2 VDC. Confirm 24 V suitability with Bolec before use. |
| Electrical system | Negative ground |
| Quiescent current | 10 mA, as listed in the electrical specification |
| Adjustment range | 0–10 VDC at the sender terminal |
| Adjustment controls | Three 25-turn potentiometers |
| Alarm outputs | Transistor switches to ground; 12/24 VDC, maximum 0.25 A per output, resistive |
| Dimensions | Approximately 58 × 42 × 29 mm overall |
| Total power dissipation | 1 W at 25°C; 600 mW at 85°C |
Supply rating and output-load notes above reflect differences within the supplied EA101 connection instructions. Check the rating of the actual unit and intended load before installation.
Check your EA101 application with Bolec
Send us the supply voltage, gauge and sender model numbers, required alarm points, and the lamp, buzzer or relay voltage and current. Mention whether you will use existing gauges or senders only.
Bolec Electronics · sales@bolec.com.au
