Sky L4-2.4L (2007)
Fuse Powering Several Loads
1. Review the system schematic and locate the fuse that is open.
2. Open the first connector or switch leading from the fuse to each load.
3. Connect a DMM across the fuse terminals (be sure that the fuse is powered).
* When the DMM displays voltage the short is in the wiring leading to the first connector or switch.
* 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.
Troubleshooting with a Digital Multimeter
Troubleshooting with a Digital Multimeter
Notice: Refer to Test Probe Notice.
Important: Circuits which include any solid state control modules, such as the engine control module (ECM), should only be tested with a 10
megohm or higher impedance digital multimeter such as the J39200.
The J39200 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:
* 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.
* 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
Troubleshooting with a Test Lamp
Notice: 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 J35616 GM-Approved Terminal Test Kit in order to
frontprobe terminals. Do not use paper clips or other substitutes as they can damage terminals and cause incorrect measurements.
A test lamp can simply and quickly test a low impedance circuit for voltage.
To properly operate this tool use the following procedure.
