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Upgrading the Headlamp Circuit on 240 Models
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Cameron Offline
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Post: #1
Upgrading the Headlamp Circuit on 240 Models
Not sure if this is the right place to put this on the forum?? Seems like it's the only "article" section though. So, move if appropriate please Smile

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/...elays.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:

[Image: HeadlightWiringDiagram.jpg]


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 :-D
01-17-2012 02:55 PM
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WindowsBreakerG4 Offline
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Post: #2
RE: Upgrading the Headlamp Circuit on 240 Models
This is the right place and this is a great contribution. I need to get some others trained so we can get these on the front page faster.

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01-17-2012 05:06 PM
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thebornotaku Offline
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Post: #3
RE: Upgrading the Headlamp Circuit on 240 Models
As an added bonus, you can change the constant-on for the headlight switch to a switched power source so that the headlights turn off with the car.

As far as relays go, I really like the Volvo 40A relay that you can find en masse in any 7 or 9 series, i used one to run my efan for the longest time and it's a simple 4-wire relay.

1985 Volvo 245DL "The Battlewagon"
1974 Volkswagen Super Beetle "Diego"
01-17-2012 05:26 PM
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Cameron Offline
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RE: Upgrading the Headlamp Circuit on 240 Models
(01-17-2012 05:06 PM)WindowsBreakerG4 Wrote:  This is the right place and this is a great contribution.

Cool.

(01-17-2012 05:26 PM)thebornotaku Wrote:  As an added bonus, you can change the constant-on for the headlight switch to a switched power source so that the headlights turn off with the car.

As far as relays go, I really like the Volvo 40A relay that you can find en masse in any 7 or 9 series, i used one to run my efan for the longest time and it's a simple 4-wire relay.

This is all true. I was also thinking it'd be cool to figure out a time delay relay to use in this application. Say, 10 second delay or so from key on to lights coming on. That way the bulbs don't get the on for a second, off when cranking, right back on again in KPII treatment. Should contribute to longer bulb life I'd think.
01-17-2012 08:42 PM
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volvogeek Offline
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Post: #5
RE: Upgrading the Headlamp Circuit on 240 Models
(01-17-2012 08:42 PM)Cameron Wrote:  This is all true. I was also thinking it'd be cool to figure out a time delay relay to use in this application. Say, 10 second delay or so from key on to lights coming on. That way the bulbs don't get the on for a second, off when cranking, right back on again in KPII treatment. Should contribute to longer bulb life I'd think.
I was going to do this for the HIDs I bought for my '86, and it's actually very easy. Found an article online for the DIY'er, cap, transistor and a resistor: http://www.diymobileaudio.com/forum/how-...rcuit.html

[ Richard Langis ] [ Yeti | Betty | MooMoo ]
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01-19-2012 07:20 AM
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volvogeek Offline
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RE: Upgrading the Headlamp Circuit on 240 Models
Actually I think you can do it with just a capacitor (20v 1000uf or more) connected between 85 and 86...

[ Richard Langis ] [ Yeti | Betty | MooMoo ]
[Image: 6818504367_35ecb7f0e7_o.jpg]
(This post was last modified: 01-19-2012 07:36 AM by volvogeek.)
01-19-2012 07:33 AM
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WolfDK Offline
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Post: #7
RE: Upgrading the Headlamp Circuit on 240 Models
In euroland we have automatic running lights, basically do the relay like OP showed but power the relay from the generators D+ instead. When generator is charging you have running lights, you should keep the original connection from the switch and run the relay in parallel (in case of a generator fail)

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07-06-2013 05:22 PM
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