Diagnostic Aids
TROUBLESHOOTING TEST PROCEDURESTESTING FOR VOLTAGE
Voltage Check:
1. Connect one lead of a test light to a known good ground. When using a voltmeter, be sure the voltmeter's negative lead is connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal).
3. If the test light illuminates, there is voltage present. When using a voltmeter, note the voltage reading.
TESTING FOR CONTINUITY
Continuity Check through a Switch:
1. Remove the fuse to the circuit involved.
2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test.
3. Connect the other lead to the other end of the circuit.
4. If the self-powered test light glows, there is continuity. When using an ohmmeter, low or no resistance means good continuity.
TESTING FOR VOLTAGE DROP
Voltage Drop Test:
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a voltmeter to the end of the wire (or to one side of the connection or switch) which is closer to the Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch).
3. Operate the circuit.
4. The voltmeter will show the difference in voltage between the two points.
TESTING FOR SHORT TO GROUND
Testing for Short with Test Light or Voltmeter:
With a Test Light or Voltmeter
1. Remove the blown fuse and disconnect the load.
2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered).
3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or voltmeter.
4. When the test light glows, or the voltmeter registers, there is a short to ground in the wiring near that point.
Testing for Short with Self-Powered Test Light or Ohmmeter:
With a Self-Powered Test Light or Ohmmeter
1. Remove the blown fuse and disconnect the Battery and load.
2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side.
3. Connect the other lead to a known good ground.
4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point.
Fuses Powering Several Loads
1. Open the first connector or switch leading from the fuse to each load.
2. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described previously.
^ If fuse does not blow, refer to next step.
3. Close each connector or switch until the fuse blows in order to find which circuit the short is in. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals.