Either you are getting no power to the headlight switch, the headlight switch needs work, or the headlight ground needs service.

Quick headlight switch test:
   Meter set to read at least 20 DC Volts...
Check the headlight switch wires for power. 
   Attach the Black or (-) meter probe to the battery ground.
   Ignition switch on, headlight set to LO beam, put meter Red (+) probe to CT90 White to measure low beam Voltage.
Same test, meter Red (+) to Blue measures high beam Voltage.

Quick headlight Ground quality test:
Ignition switch ON.  Headlight switch set to LO beam.
1) Measure headlight Voltage between headlight White, and headlight Green ground wire (in the headlight bucket).
2) Measure headlight Voltage between headlight White and the Ground wire at the battery.

These two Voltages should be almost exactly the same. The headlight bucket ground would technically be slightly less since the wire is longer.

If the headlight bucket ground measures a lot less (like 2/10ths of a Volt or less) than the directly grounded test, the headlight bucket Ground wiring requires service.

If the headlight bucket Ground wire test measures low to no Voltage, the headlight Ground circuit is broken, and requires repairs.



Last Edited By: JPardue Jan 7 14 11:59 AM. Edited 1 times.