Section 2
TM 9-2320-363-20-1
BASIC KNOWLEDGE REQUIRED (Cent’d.)
3. Put one test lead probe at one end of the wire or circuit to be tested. Use the other test lead to trace the
4
circuit. When continuity is established, an n symbol will appear in the upper left corner of the digital display.
If contact in the wire is maintained long enough (about 1/4 of a second), the OL will disappear and the
resistance value of the wire or circuit will appear next to the symbol.
If your VOM does not work in the manner described above, you must know how your VOM operates in order to
use this troubleshooting guide.
Voltage Measurements
1.
2.
3.
Connect the red test lead to the V- A input connector and the black lead to the com input on the meter.
If a DC-AC switch is present, make sure it is switched to the DC position.
Set the function/range switch to the desired volts position. If the magnitude of the voltage is not known, set the
switch to a range which will be able to read most voltages seen on a vehicle. (Typically, a 20V range will do.)
Then reduce the range until a satisfactory reading is obtained.
Connect the test leads to the circuit being measured. In the DDEC II diagnostic procedures, voltage
measurements are always given as being taken at pins. sockets, Battery + or ground. Following the voltage
measurement point, the color test lead to be used is given in parenthesis (red is the V- n connection, and
black is the com connection).
C. IMPORTANT INFORMATION
The following items must be read and thoroughly understood before using this manual.
1. The engine and ignition should always be off before the harness connectors are disconnected or reconnected.
2
3.
When disconnecting harness connectors, be sure that the pulling force is applied to the connectors themselves and
not the wires extending from them.
After harness connectors are reconnected to the DDEC II system, the computer diagnostics should be ignored and
cleared.
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