Troubleshooting / One Dim Headlight

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Why is One Headlight Dim?

Introduction

As far as the lighting in your vehicle goes the headlights are among the most important. These headlights draw a significant amount of amperage. This amperage usage strains the voltage supply system causing malfunctions. One of the most common failures is one dim headlight. This problem seems like it would be hard to repair but surprisingly it is not. A simple test and repair are all that is required to fix this problem. Follow the test the repair guide below.

Headlight Lens

Troubleshooting Procedure - READ COMPLETELY BEFORE BEGINNING
 

• Attach a test light lead to good ground source - How to use a test light
   
• Gain access to the rear of the headlight, you may have to remove the headlight or locate the wiring harness that feeds the headlight in question.
   
  
• Turn the headlights to the on position, regular mode, not high beam (do not start the engine). Using the test light probe the headlight electrical connector. Two out of three terminals on the connector will cause the test light to illuminate.
   
  
• Remove the electrical connector from the headlight. With the headlights still "on" test the electrical connector, one of the two that had power will still have power. The terminal that had power before the headlight connector was removed and now does not is the problem. This wire/connection is the "ground" circuit for the headlight.
   
  
• This ground completes the electrical circuit. The reason the headlight is dim is because the full voltage cannot be delivered to the headlight filament. Clean or reconnect the ground circuit wire to a new ground source and recheck headlight operation. Reassemble as needed.

For exact specific repair procedures to remove a particular headlight please visit our online repair manual page.

Troubleshooting / One Dim Headlight

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