FREE ASE PREP Automotive Lights Online Training and BAR Specific Diagnostic Course – Automotive Electrical Class: Lights:
Having an understanding of the Automotive-Lights for ASE A6 test may help you earn your ASE Certificate
Gauges, which indicate various vehicle conditions such as coolant temperature, oil pressure, fuel level, and battery condition.
Warning: Before you condemn a switch or gauge check the operation of that circuit.
Example: Temperature gauge is stuck low or high before you replace the gauge check the coolant system.
When diagnosing lights, understanding how to read a wiring diagrams are essential.
Here is an example: you have a dim headlight, you replace the light, guess what it’s still dim now what! Try another brand. No!
Most likely you have a resistance problem, time to perform a voltage drop.
When the bulbs are brighter then normal this indicates a problem, the wrong bulb could be install, the alternator could be putting out to much voltage due to a defective voltage regulator.
When the bulbs are dimmer then normal, this could be do to a bad alternator not charging or the belt on the alternator is slipping. Also always check the battery, a defective battery will affect all your electrical components.
Perform a voltage drop on the hot side and the ground side of the circuit. excessive voltage drop means an increase in resistance.
The voltage and current is now reduced to lights and they will go dim.
How about if the lights do not work at all or intermittently, check the fuses or fusible links and circuit breakers. A faulty switch or loose connections could also be the corrupt.
FREE ASE PREP Automotive Lights
When changing bulbs you have to be careful also some bulbs will prematurely fail if they touch your skin.
Headlamp and dimmer switches could be in series of each other or the dimmer switch could be on the ground side like some imports.
There are usually three positions:
First position: Off
Second position: current flows to the parking, tail lamps, and other circuits
Third position: current flows to both the second position circuits and to the headlamps circuit
Daytime running lamps have a special module or controller that sends a reduce voltage signal to the lamps, some manufacturer’s install the high beams in series to cut down the voltage to each lamp in half.
The lights will usually go out if you apply the parking brake
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