TM 9-4940-568-20
2-55
Table 2-7. Engine Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
5. AN AMBER WARNING LAMP IS ON.
The PRE LO OIL PRES lamp comes on while the engine is running.
Shut down the engine if possible or disconnect non-critical loads. (Oil pressure will be less
than 20 psi [138 kPa] but greater than 14 psi [97 kPa]). Check engine oil level. If oil level
is ok, perform engine oil service (Para 8-2).
The PRE HI ENG TEMP lamp comes on while the engine is running.
Shut down the engine if possible or disconnect non-critical loads. (Engine temperature will
be greater than 220 F [104 C] but less than 230 F [110 C].) Check engine coolant level
and fill if necessary. Low coolant level switch S7 is wired in series with this circuit.
The LOW ENGINE TEMPERATURE lamp comes on prior to starting the engine.
a. Plug in engine coolant heater (TM 9-4940-568-10), and allow coolant to warm up.
b. If coolant does not warm up, replace engine coolant heater (Para 8-27)
6. THE GREEN RUN LAMP STAYS OFF BUT THE SET RUNS NORMALLY.
The RUN lamp does not light, although the starter has disconnected normally and the engine is running.
a. Press the panel Lamp Test switch and replace the RUN lamp bulb if it does not light.
b. If lamp is good, this indicates that the AC disconnect circuit is not working. Check the
AC voltmeter to determine whether or not there is generator output voltage and service as
necessary. Refer to Generator Troubleshooting Step 1 No Output Voltage.
c. If there is generator output voltage, check for 120 VAC across pin connectors P1-1 and
P1-2 on the A11 card. If there is no voltage, check for loose or missing leads between the
connectors and TB21-21 and TB21-32 inside the control box and service as necessary.
d. Notify Direct Support to test generator if there is 120 VAC across pin connectors P1-1
and P1-2 on A11 card but RUN lamp lights during normal operation.
