ELECTRICAL TROUBLESHOOTING
TM 5-3805-263-14&P-3
EMS PANEL
Continuity
No Continuity
The harness is good. Replace the operator panel.
Use the electrical schematic or the simplified schema-
tic to find the harness with an open (broken) wire
Replace the harness.
3. Check for continuity between the ground connection on the oil pressure switch (B/W
wire) and machine ground. Use a continuity tester or a digital multimeter.
Continuity
No Continuity
The ground connection is good. Either the pressure
Replace the harness or fasten a wire from the switch
switch has a failure in the open position or there is a
ground connection to machine ground.
failure in the oil pump. Go to Step 4.
4. Turn the fuel OFF.
Remove the oil pressure switch and put a thumb over the opening.
Have another serviceman turn the start switch to the START position so that the
starter motor turns the engine. (Do not turn the engine for more than 30 seconds.)
An increase in oil pressure must be felt.
Oil Pressure Is Felt
Oil Pressure Is Not Felt
Install a pressure gauge in the opening for the pres-
Make repairs as necessary.
sure switch and make a test for oil pressure. If oil
pressure is correct, make a replacement of the oil
pressure switch. If oil pressure is not correct, make
repairs as necessary.
Engine Coolant Temperature Or
Hydraulic Oil Temperature Indicator
Follow the instructions given at the first of the section on the monitoring system, to
make sure the system is cool enough for the indicator to turn OFF. If the indicator
does NOT turn OFF, make a check of the electrical system as follows:
1. Disconnect the control wire from the temperature switch of the indicator that is ON
(See TABLE 4).
TABLE 4
Indicator
Switch
Control Wire Color
Engine Coolant Temperature
7N9785
R/W
Hydraulic Oil Temperature
3T 190
Y / PU
4-38
