Tahoe 4WD V8-393 6.5L DSL Turbo VIN S (1995)
3. 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.
^
If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead,
touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much
voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits
should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a
test light on circuits that contain solid state components, since damage to these components may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R)
connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact
surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of
probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and
cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are
touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points
along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test
light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO
resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher
impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs
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 an ohmmeter to give a false reading. To find out if a component is affecting a measurement,
take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is
supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit
being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and
shows you the location of the short through body trim or sheet metal.
