APS (Air Pressure System) is the compressed air circuit feeding vital functions such as braking and gear shifting on heavy vehicles. It is common on long-haul vehicles, particularly Scania tractor units.
A fault here has serious consequences: braking performance and gear changes are directly affected.
How Does an APS Fault Show Itself?
The warning usually arrives as a lamp on the dashboard. On its own that lamp does not tell you:
- Which area the fault is in
- What caused it
- Whether it is on the brake side or the transmission side
Acting without answering those three questions is guesswork. On a heavy vehicle, guessing about the brake circuit is not acceptable.
Safety Warning
If the fault involves the brake circuit, the vehicle must not be driven. An APS warning is not one to ignore.
What Proper Diagnosis Requires
- Reading the brake and transmission control units separately
- Comparing pressure sensor live data against actual system pressure
- Testing solenoid and modulator valves from the tool
- Assessing leaks and dryer condition as part of the whole system
This requires a diagnostic tool with heavy vehicle coverage. A basic OBD reader cannot reach these modules.
Which Tool Is Used?
The Spanish-made Jaltest diagnostic tool is among the solutions capable of reliable diagnostics across many heavy vehicle brands including Scania. Brake, transmission, engine and trailer modules can all be reached from one tool.
Under Nitro Mekatronik distribution, Jaltest tools are sold not only in Turkey but across the Middle East and Africa.