Yukon/Denali 4WD V8-4.8L VIN V (2005)
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When the DMM displays voltage the short is in the wiring leading to the first connector or switch.
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If the DMM does not display voltage refer to the next step.
4. Close each connector or switch until the DMM displays voltage in order to find which circuit is shorted.
Testing For Short to Voltage
TESTING FOR A SHORT TO VOLTAGE
NOTE: Refer to Test Probe Notice in Service Precautions.
The following procedure tests for a short to voltage in a circuit.
1. Set the rotary dial of the DMM to the V (DC) position.
2. Connect the positive lead of the DMM to 1 end of the circuit to be tested.
3. Connect the negative lead of the DMM to a good ground.
4. Turn ON the ignition and operate all accessories.
5. If the voltage measured is greater than 1 volt, there is a short to voltage in the circuit.
Troubleshooting With A Digital Multimeter
TROUBLESHOOTING WITH A DIGITAL MULTIMETER
NOTE: Refer to test probe notice in service precautions.
IMPORTANT: Circuits which include any solid state control modules, such as the PCM, should only be tested with a 10 megohm or higher impedance
digital multimeter such as the J 39200 .
The J 39200 instruction manual is a good source of information and should be read thoroughly upon receipt of the DMM as well as kept on hand for
future reference.
A DMM should be used instead of a test lamp in order to test for voltage in high impedance circuits. While a test lamp shows whether voltage is
present, a DMM indicates how much voltage is present.
The ohmmeter function on a DMM shows how much resistance exists between 2 points along a circuit. Low resistance in a circuit means good
continuity.
IMPORTANT: Disconnect the power feed from the suspect circuit when measuring resistance with a DMM. This prevents incorrect readings.
DMMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause a DMM to display a false reading. To find out if a component is affecting a measurement take
a reading once, then reverse the leads and take a second reading. If the readings differ the solid state component is affecting the measurement.
Following are examples of the various methods of connecting the DMM to the circuit to be tested:
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Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for
continuous monitoring while you perform other operations or test driving. Refer to Probing Electrical Connectors.
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Disconnect the harness at both ends of the suspected circuit where it connects either to a component or to other harnesses.
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If the system that is being diagnosed has a specified pinout or breakout box, it may be used in order to simplify connecting the DMM to the circuit
or for testing multiple circuits quickly.
Troubleshooting With A Test Lamp
TROUBLESHOOTING WITH A TEST LAMP
TOOLS REQUIRED
J 35616-200 12-Volt Unpowered Test Lamp
NOTE: Refer to Test Probe Notice in Service Precautions.
A test lamp can simply and quickly test a low impedance circuit for voltage.
The J 35616-200 is Micro-Pack compatible and comprised of a 12-volt light bulb with an attached pair of leads.
To properly operate this tool use the following procedures.
When testing for voltage:
1. Attach 1 lead to ground.
2. Touch the other lead to various points along the circuit where voltage should be present.
