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GI-42 < BASIC INSPECTION > SERVICE INFORMATION FOR ELECTRICAL INCIDENT Circuit Inspection INFOID:0000000005516118 DESCRIPTION • In general, testing electrical circuits is an easy task if it is approached in a logical and organized method. Before beginning it is important to have all available information on the system to be tested. Also, get a thor- • You may have to simulate vehicle vibrations while testing electrical components. Gently shake the wiring harness or electrical component to do this. NOTE: GI-36, "How to Check Terminal" to probe or check terminal. TESTING FOR “OPENS” IN THE CIRCUIT Before you begin to diagnose and test the system, you should rough sketch a schematic of the system. This Continuity Check Method The continuity check is used to find an open in the circuit. The digital multimeter (DMM) set on the resistance tion of the circuit has good continuity. If there were an open in the circuit, the DMM would indicate an over • Connect the probes between SW1 and the relay. Little or no resistance will indicate that portion of the circuit has good continuity. If there were an open in the circuit, the DMM would indicate an over limit or infinite resis- • Connect the probes between the relay and the solenoid. Little or no resistance will indicate that portion of the circuit has good continuity. If there were an open in the circuit, the DMM would indicate an over limit or infi- Any circuit can be diagnosed using the approach in the previous example. Voltage Check Method To help in understanding the diagnosis of open circuits please refer to the previous schematic. voltage: open is further down the circuit than SW1. OPEN A circuit is open when there is no continuity through a section of the circuit. SHORT There are two types of shorts. • SHORT CIRCUIT When a circuit contacts another circuit and causes the normal resistance to • SHORT TO GROUND When a circuit contacts a ground source and grounds the circuit. SGI846-A |