Why techs fail A6
Most technicians study A6 by memorizing wiring colors and connector pinouts for the vehicles they work on. The test does not ask those questions. It asks you to trace a circuit on a diagram you have never seen and predict what will happen when one wire opens or shorts. If you cannot read a strange diagram fast, you will fail.
The four circuit types to master
Series, parallel, series-parallel, and control circuits with switched ground versus switched power. For each, know what happens to voltage and current when you introduce an open in a specific location. Ohm's law questions on the exam are almost always disguised as scenario questions about a bulb getting dim or a motor running slow.
Practice with printed wiring diagrams. Cover the answer, trace the circuit, predict the outcome, then check yourself.
Voltage drop is the whole test
Expect at least five questions that hinge on voltage drop. Learn the SAE limits by heart: 0.1 volt across a connection, 0.2 volts across a switch, 0.3 volts on a ground path, and no more than 0.5 volts total in a circuit. A tech who reflexively reaches for the voltmeter instead of the ohmmeter on a live circuit will pass A6.