What an immobiliser actually cuts
A professional tracker has digital outputs: switches the server can open and close. An immobiliser install puts a relay on one of them, in the circuit that feeds the starter motor. With the output off, the relay is at rest and the vehicle starts normally. With it on, the starter circuit is open, and turning the key does nothing.
Cutting the starter, rather than the fuel pump or the ignition, is deliberate. A vehicle that loses its engine at 80 km/h on a Lagos expressway is a danger to everyone on the road, including the driver who stole it. Cutting the starter means the engine already running keeps running until it is switched off, and then it cannot be started again. A thief who stops for fuel, a checkpoint or the night is stranded where they stopped.
How the command reaches the vehicle
- A manager opens the vehicle and chooses to immobilise it. The dashboard asks for confirmation naming the vehicle, so it cannot happen from a stray click.
- FuelSense sends Teltonika’s setdigout command over the connection the tracker keeps open on the mobile network.
- The tracker replies with the state its outputs are now in. That is the acknowledgement.
- In its next reports the tracker includes the output’s level (AVL element 179 for DOUT1). That is the confirmation that the relay side really changed.
The dashboard shows those three steps separately: sent, acknowledged, confirmed. It does not collapse them into a single “done”, because a command that left the server is not the same as a vehicle that cannot start.
When the tracker is out of coverage
A tracker dials the server, never the other way round, so a vehicle in a coverage gap cannot be commanded at that moment. The cut is queued and delivered on the tracker’s next connection, however long that takes. A release always supersedes an engage that has not been delivered yet, so changing your mind is never blocked by a queue.
What it takes to set up
- A tracker with a digital output: the Teltonika FMC130 and FMC150 both have two.
- A relay wired into the starter circuit by the installer, normally on DOUT1, at the time the tracker is fitted.
- A test from the dashboard while the installer is still there: engage, try the key, release, start.
Where the vehicle’s central locking is wired to the second output, the same dashboard can also lock every door with a one-second pulse, the way the key fob does. Unlike the immobiliser that command is never queued: a lock that arrives hours later is not what anyone asked for, so it only goes to a tracker that is connected right now.
Accountability
Every engage and release is an audit event with the person who sent it and the time, kept for as long as the vehicle is on the account. A manager reviewing an incident months later sees exactly who stopped which vehicle, when the tracker acknowledged it, and when it was released.
Common questions
- Will the engine cut out while the vehicle is driving?
- No. The relay is in the starter circuit, so a running engine keeps running. The vehicle cannot be restarted after it is switched off.
- What happens if the tracker loses power?
- With the output off the relay is at rest and the vehicle starts normally, so a tracker fault does not strand a working vehicle. A tracker power loss raises its own alert in FuelSense.
- Can a driver release it themselves?
- No. Engaging and releasing are manager actions in the dashboard, and both are logged.
- Does it work without mobile signal?
- The command needs the tracker to connect. If it is out of coverage the command waits and is delivered on its next connection.