Storm L4-1800cc 1.8L DOHC (1993)
Fig. 1 Typical Headlights Schematic
2. Read the headlights electrical schematic, see Fig.5. This is the step that will save time and labor. Remember, it is essential to understand how a
circuit should work, before trying to figure out why it doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating
the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal
"1E" of C100, the TAN wires and grounds G105 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came on when
the headlight Dimmer Switch was moved to "HI," you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire
between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in "HI." However, it is extremely unlikely that
the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one
specific area, and have done absolutely no work on the vehicle itself.
3. Find the fault and repair it. Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN
wire, locate the exact trouble point and make the repair.
4. Check the repair by performing a system check on the headlights circuit. This, of course, means making sure that both HI beams, both LO
beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but
neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI
beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector.
Troubleshooting Tools
TEST LIGHT/VOLTMETER
Use a test light to check for voltage. A Test Light is made up of a 12 volt light bulb, with a pair of leads attached. After grounding one lead, touch
the other lead to various points along the circuit where voltage should be present. When the bulb goes on, there is voltage at the point being tested.
A voltmeter can be used instead of a test light. While a test light shows whether or not voltage is present, a voltmeter indicates how much voltage
is present.
An increasing number of circuits include solid state control modules. One example is the Electronic Control Module (ECM). Voltages in these
circuits should be tested only with a 10-megaohm or higher impedance digital voltmeter or multimeter. Unless directed to within the diagnostics,
never use a test light on circuits that contain solid state components, since damage to these components may result.
