TM  10-3930-638-24&P 2-25.   INSTRUMENT   PANEL   TROUBLESHOOTING   (cont) MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION 1.  WARNING  LIGHTS  INOPERATIVE  (cont) Step 2. (cont) a. b. If warning light is on during test, and inoperative during high temperature or low oil pressure vehicle operation,  replace  associated  warning  light  switch (para 2-28e). If warning light is not on, check for open circuit in wiring  or  40  ohm  resistor  between  inoperative warning light and associated warning light switch. 2. WARNING  LIGHTS,  BACK-UP  ALARM  AND  ELECTRIC  FUEL  PUMP  INOPERATIVE Turn IGNITION switch key to ON position and depress START switch. a. If starter cranks engine, replace 6 ampere circuit breaker at IGN terminal of IGNITION switch. b. If starter does not crank engine, connect voltmeter leads to BATT terminal of IGNITION switch and vehicle ground. If voltmeter indicates 24 Vdc, replace IGNITION switch (para 2-28c). If voltmeter does not indicate 24 Vdc, check for open circuit in wiring between IGNITION switch BATT  terminal  and  25  ampere  circuit  breaker. 2-113