TM 9-6115-664-13&P Table 4-4.  LED and Test Point Table LED or Test Point Location Indication LED 1 - AIR PH Engine preheat module Illuminates when are engine air heater elements are energized (PREHEAT OIL/AIR switch is in AIR position). LED 2 - OIL PH Engine preheat module Illuminates when are engine oil heater elements are energized (PREHEAT OIL/AIR switch is in OIL position). LED 1 - RUN Local control panel   * Illuminates when engine run signal is sent to engine (START/RUN AND PRIME/OFF switch is in RUN position). LED 2 - START Local control panel   * Illuminates when engine is cranking (START/ RUN AND PRIME/OFF switch is in START position). LED 3 - LOP Local control panel   * Illuminates when engine oil pressure drops below acceptable limit. LED 4 - HT Local control panel   * Illuminates when engine temperature exceeds acceptable limit. LED 5 - APU ON Local control panel   * Illuminates when APU output contractor is engaged (closed). LED 8 - HIGH ENGINE Remote control panel Illuminates when engine temperature exceeds TEMPERATURE acceptable limit. LED 9 - LOW OIL Remote control panel Illuminates when engine oil pressure drops below PRESSURE acceptable limit. LED 10 - APU ON Remote control panel Illuminates when APU output contractor is engaged (closed). LED 11 - Battle Short ON Remote control panel Illuminates when APU is operating in battle short conditions (BATTLESHORT switch activated). Test Point TP 1 Local control panel   * Ground / common test point. Test Point TP 2 Local control panel   * 28 VDC system test point. Test Point TP 3 Local control panel   * Alternator AC signal. * Local control panel LEDs and test points are located on the back of the control panel, under the top rear APU cover (see Figure 2-1).  Turn latches and open cover to gain access. 4-12