Do I understand it correctly that I can only use the DIN1 input to either receive ignition detection, alarm button or door sensor, and similarly with all the other inputs and outputs?
I understand that for the ignition cut to work, I have to cut the wire between ignition detection and the starter. But I’m seriously confused about the relay diagram. Do I wire the ignition detection side to both 87a and 86 at the same time? Does relay 85 somehow cut the connection between 30 and 87a? How does this work?
Are those aforementioned relays usually occupied or are they redundant on cars
4. I want to have a fuel sensor input on AIN1 so that I can monitor the fuel consumption per trip - this was my main aim in getting this tracker. But how does it work? Do I need to get a custom sensor and wire it? Or can I simply splice into the wire between the car’s LLS sensor and the fuel gauge?
Yes, you understand correctly. DIN1 is a digital input channel 1, dedicated for ignition input, and alarm buttons, door sensors, ignition, etc. return two states: high or low voltage. Digital inputs are used to read this information.
2)The relay diagram can be confusing, so let me break it down clearly:
Relay Pin Functions:
The coil has two connection points; they are labeled 85 and 86 on an SPDT relay. The coil generates a magnetic field when current is passed through it
85 and 86 are the coil pins while 30, 87, and 87a are the contact pins. 87 and 87a are the two contacts to which 30 will connect. If the coil is not activated, 30 will always be connected to 87a
How It Works:
Without power to coil (85 86) 30 is shorted to 87a. When applied, power 30 shorts to 87
Pin 87a is a “switched” pin, ie after applying voltage to 85 and 86, circuit 30-87 switches on, and disconnects 30-87a. This contact is used when you want to disconnect the circuit by energizing a relay
For Ignition Cut Wiring:
Cut the ignition wire between the ignition switch and the starter
Connect the two cut ends:
One end to pin 30 (common)
Other end to pin 87a (normally closed contact)
Control circuit (from FMB920 DOUT1):
85 will be used to ground your relay, while 86 will be connected to the switchable power
Connect 12V to pin 86
Connect pin 85 to DOUT1
Normal Operation: When DOUT1 is OFF, no power flows through the coil (85-86), so pins 30 and 87a remain connected, allowing the ignition circuit to work normally.
Immobilization: When the coil is energized it opens the circuit so that the starter wire is disconnected (open circuit). When you activate DOUT1, it energizes the relay coil, which breaks the connection between 30 and 87a, cutting power to the starter.
Pin 87 is not used in this configuration - it remains unconnected.
Most modern vehicles have multiple relays for various systems (fuel pump, headlights, cooling fans, etc.), but the relay you’re adding for GPS tracker immobilization is typically an additional aftermarket component, not replacing an existing relay.
FMB920 supports fuel monitoring via AIN1! You have two options:
Option A: Use a Dedicated LLS (Liquid Level Sensor)
Purchase and install a separate analog fuel level sensor
Wire it directly to AIN1
Requires drilling into the fuel tank (professional installation recommended)
Option B: Splice into Existing Fuel Sender Wire (Recommended for simplicity)
To do that (for both options), go to I/O elements and select Analog Input 1 to Low/High priority. The Operand of the I/O element should be left as Monitoring. You will see changes in fuel level expressed by the equivalent voltage read from the fuel sender wire to the Analog Input of your Teltonika device.
