C 2500 Truck 2WD V8-6.0L VIN U (2002)
![background image](/chevrolet/c_2500_truck_2wd/v8-6.0l_vin_u/Page-306006.png)
-
Troubleshooting with a Digital Multimeter
-
Troubleshooting with a Test Lamp
-
Using Fused Jumper Wires
-
Measuring Voltage
-
Measuring Voltage Drop
-
Measuring Frequency
-
Testing for Continuity
-
Testing for Short to Ground
-
Testing for a Short to Voltage
Probing Electrical Connectors
IMPORTANT: Always be sure to reinstall the connector position assurance (CPA) and terminal position assurance (TPA) when reconnecting
connectors or replacing terminals.
Frontprobe
Disconnect the connector and probe the terminals from the mating side (front) of the connector.
NOTE: Do not insert test equipment probes into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A
deformed terminal can cause a poor connection, which can result in system failures. Always use the J 35616-A Connector Test Adapter Kit or the J
42675 Flat Wire Probe Adapter kit in order to frontprobe terminals. Do not use paper clips or other substitutes as they can damage terminals and cause
incorrect measurements.
Backprobe
Important:
-
Backprobe connector terminals only when specifically required in diagnostic procedures.
-
Do not backprobe a sealed (Weather Pack(R)) connector, less than a 280 series Metri-Pack connector, a Micro-Pack connector, or a flat wire
(dock and lock) connector.
-
Backprobing can be a source of damage to connector terminals. Use care in order to avoid deforming the terminal, either by forcing the test probe
too far into the cavity or by using too large of a test probe.
-
After backprobing any connector, inspect for terminal damage. If terminal damage is suspected, test for proper terminal contact.
Do not disconnect the connector and probe the terminals from the harness side (back) of the connector.
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 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:
-
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. See: General Electrical
Diagnostic Procedures/Troubleshooting Tools/Probing Electrical Connectors
-
Disconnect the harness at both ends of the suspected circuit where it connects either to a component or to other harnesses.
-
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
TOOLS REQUIRED
J 34142-B 12 V Unpowered Test Lamp