Cameron
ドクターマリ&#
- Joined
- Dec 6, 2006
- Location
- Crawling around under the car
Secondary title: Stop Melting Your Headlamp Switch
Volvo 240 models headlamps came from the factory running all the power to the headlight through the switch in the dash. This is not a great way to do things and is asking a switch to carry a load it is not built to handle long term. The result in my experience is a larger than desired voltage drop from battery to lights (dim headlights) and meltage issues over longer periods in the switch and connector.
Most people know of the "Daniel Stern" method of upgrading your headlamp circuit. His is a superior method to what I will outline here, but also is more involved and requires additional parts and wire routing. More on his method here: http://www.danielsternlighting.com/tech/relays/relays.html
The idea with what I'm writing here is a super simple way to improve the circuit with minimal wiring changes and just a couple bucks in parts. A cheap mod that provides less voltage drop to the lights (brighter headlights) and no more melty switches.
The entire gist of this is that we're hijacking the power wire between the headlamp switch and the headlamp step relay on the inner fender next to the battery. Instead we're going to use that power out of the switch to trigger a relay which then sends the power to the step relay instead.
Here's what the diagram looks like:
Really, the only parts you'll need to buy is a SPST (single pole single throw) relay and a fuse/holder. I used a basic 40amp relay from Radio Shack. It cost all of $5.00 and you can find it HERE. For the fuse you can use whatever you want. I'd recommend going for something waterproof since you'll likely be installing this in the engine bay... I used THIS ONE.
With those supplies in hand you'll just need a couple spade connectors to hook it all up. Mount the relay and fuse, reroute a couple wires and you're done. Easy peasy
Volvo 240 models headlamps came from the factory running all the power to the headlight through the switch in the dash. This is not a great way to do things and is asking a switch to carry a load it is not built to handle long term. The result in my experience is a larger than desired voltage drop from battery to lights (dim headlights) and meltage issues over longer periods in the switch and connector.
Most people know of the "Daniel Stern" method of upgrading your headlamp circuit. His is a superior method to what I will outline here, but also is more involved and requires additional parts and wire routing. More on his method here: http://www.danielsternlighting.com/tech/relays/relays.html
The idea with what I'm writing here is a super simple way to improve the circuit with minimal wiring changes and just a couple bucks in parts. A cheap mod that provides less voltage drop to the lights (brighter headlights) and no more melty switches.
The entire gist of this is that we're hijacking the power wire between the headlamp switch and the headlamp step relay on the inner fender next to the battery. Instead we're going to use that power out of the switch to trigger a relay which then sends the power to the step relay instead.
Here's what the diagram looks like:
Really, the only parts you'll need to buy is a SPST (single pole single throw) relay and a fuse/holder. I used a basic 40amp relay from Radio Shack. It cost all of $5.00 and you can find it HERE. For the fuse you can use whatever you want. I'd recommend going for something waterproof since you'll likely be installing this in the engine bay... I used THIS ONE.
With those supplies in hand you'll just need a couple spade connectors to hook it all up. Mount the relay and fuse, reroute a couple wires and you're done. Easy peasy
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