86-91 Headlight Harness Damage

As our vans get older, the resistance inside the wiring increases.  This presents two issue for our aging headlights.  

The first is that the higher resistance in the wires decreases the voltage that can get to the bulbs, which in turn results in decreased headlight output.  

The second is that the high resistance can also cause a lot of extra heat.  This can melt connectors and cause erratic headlight outages or complete system failure.

The photo above shows the result of a combination of running high wattage bulbs and most likely having bad grounds for the headlights.  

The damage to the stock 9004 plug is usually contained to the ground (left) and high beam (middle) terminals and is most commonly found when running 100/80W 9004 bulbs in the main outer lenses 

and 100W H3 bulbs in the inner high beam lenses.

Oxidation and corrosion can (and generally will) happen to any electrical connection that is exposed to the elements.  These were the factory terminals for the inner high beam connections on my old '87 Wolfsburg.  Replacing the plain brass terminals with tinned (zinc plated) terminals and adding dielectric compound to the terminals can significantly extend the time frame before the onset of corrosion begins.