Initial Inspection and Diagnostic Overview

Analogue Instrument:

Digital Instrument:

Wiring diagrams and high-quality instruments, together with a knowledge of their use and maintenance, are essential to tracing and correcting faults in electricalsystems.

Most of the Instruments normally used feature either an analogue or a digital display. In the analogue type, the reading is indicated by movement of a needle or indicator over a fixed scale, while a digital instrument displays a direct numerical readout of the measured value.

Electrical systems in cars equipped with alternamators are of the direct-current type, the alternating current generated being rectified.

Direct and alternating current are denoted by the abbreviations d.c. and a.c.