BASIC KNOWLEDGE REQUIRED (Cont'd.)
Put one test probe at one end of the wire or circuit to be tested. Use the other test lead to trace the circuit.
When continuity is established, an Q 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.
Connect the red test lead to the V-n 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. (Typical, 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 III 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-Q
connection, an black is the com connection). Example: If the procedure says, "Take voltage reading at
socket C2 (red lead) to socket K1 (black lead)"', the hook-up would be as follows:
The following items must be read and thoroughly understood before using this manual.
The engine and ignition should always be off before the harness connectors are disconnected or
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 III system, the codes logged should be ignored and
cleared. 4. In most all areas of Repair/Troubleshooting, a diagnostic data reader will be required.
3-345.8 Change 3