Troubleshooting

Start with tsync_diag in the client console (F8). The last pass re-phased N vehicle(s) line splits every problem below into two halves: N is zero means the vehicles are failing a selection rule, N is not zero means the reset is running and something else is wrong.

Nothing syncs, and the count is zero

The vehicles are failing one of the four rules. Walk them in this order.

Are the lights actually on? tSync never switches anything on. A vehicle with its light bar dark is not a candidate, and this is the answer more often than the other three combined.

Is the fleet class 18? Check classes in the diag output against your vehicles. A surprising number of emergency vehicle mods ship as class 0 (Compact) or 19 (Military) because the author never set it. Add the class to Config.vehicleClasses — you are not restricted to one.

Are they within radius? The default is 150 m. If you are testing by spawning two cars and standing back, you may be outside it.

Is something else claiming them? If deferring to: names a resource, tSync is skipping vehicles that resource knows about. That is correct behaviour — see Configuration.

Nothing syncs, and the count is not zero

tSync is re-phasing vehicles and they are still out of step. That means the reset is not reaching the lights, which points at the lighting script rather than at tSync.

A script that draws its own lights cannot be synced this way. There is no engine timer behind rendered LEDs to restart. tSync is for vehicles GTA is lighting; if yours are drawn by a script, that script owns their timing and needs its own sync feature.

Two sync systems fighting. ULC has its own park sync. Running both is harmless but pointless — they will re-phase on different schedules and the lights will appear to settle twice. Turn ULC's off, or stop tSync.

The lights blink every few seconds

That is the frame gap, and it should not be visible. If it is, intervalMs is probably very low — at a few hundred milliseconds the reset happens often enough to read as a stutter rather than as nothing.

Raise intervalMs. The default of 5000 is not visible on any hardware tested.

The siren audio clips or restarts

The vehicle is using the siren flag for audio as well as lights, and the reset is interrupting it.

If a lighting script owns the vehicle, leave Config.deferToTLS = true and make sure the diag line names it. If nothing claims the vehicle and the clipping is still unacceptable, raise intervalMs so it happens less often, or remove that vehicle's class from Config.vehicleClasses.

Errors naming tLib

attempt to index a function value

tLib is older than v1.0. A tLib module that does not exist is not nil — it is a truthy export proxy, so no if tlib.config guard catches it and the failure surfaces partway down a script instead of as "update tLib". Update tLib.

tSync: tLib is required

tLib is not started, or is started after tSync. ensure tLib must come first in server.cfg.

Configuration errors at boot

A red block naming a key, the file and the fix. tSync does not start until it is resolved, which is deliberate — a resource running on a configuration it has already reported as wrong is harder to diagnose than one that refused to start.

Fix the key in config.lua and restart. tsync_diag re-runs the same checks without a restart, so you can confirm a fix before you apply it.

It works for me but not for other players

It is working for both of you, separately.

The reset re-phases what your client draws. Another player's client runs its own pass on the same shared clock and reaches the same result for the vehicles near them. There is no state to be out of sync, and nothing to check — if a second player sees drift, run tsync_diag on their client and work the selection rules above there.