# 08-15 Gen4 - BTMS inspection and cleaning

This procedure is applicable for the LionC Gen4 only

The Battery Thermal Management System (BTMS) is a self-contained unit located under the bus, on the passenger side, bolted to the frame rail behind the front door.

It’s a bulky stainless-steel box with an HV connector, two coolant hoses and a LV wiring connector on its rearward face.

It contains a PTC element for heating and an A/C unit for cooling the battery packs. Both systems are powered by the High-Voltage system.

Inspection

To inspect the BTMS unit, go under the bus and check the condition of the electrical (HV and LV) connectors and wiring.
Check there is no coolant leaking from the hoses or the connectors.

Check that the venting holes and slots on the housing are unobstructed so air can circulate freely inside the unit.
Check that the A/C unit condenser fan is unobstructed and turns freely.
Finally, confirm there is no error message or DTC on the multifunction display.