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Super Simple Headlamp Circuit Upgrade for 240 Models

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:

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
 
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M.H. Yount

New member
Joined
Nov 1, 2008
Location
Charlotte, NC
Thanks for relay link! I tend to go to automotive supply stores and then look for something that's workable; this one will also work for my upcoming fuel pump upgrade!!
 

Cameron

ドクターマリ&#
Joined
Dec 6, 2006
Location
Crawling around under the car
Thanks for relay link! I tend to go to automotive supply stores and then look for something that's workable; this one will also work for my upcoming fuel pump upgrade!!

Yup, certainly will. I used the same ones for triggering the ECU, Fuel pumps and coils with the LINK G3 ems on my 16v wagon. Never a problem with them. I think they carry 50amp rated ones too if you want a slightly burlier one and they're still under $10.00 each.
 

neptune

just 8 cars
Joined
Jun 11, 2004
Location
Lake Forest Park, WA
If I remember correctly the later cars have this setup from the factory. Starting sometime around 87? I think the relay is mounted under the dash somewhere.

I did it to my 242 years ago when I changed to the later headlight switch. Mounted the relay next to the Lambda Sond relay on the inner fender. Absolutely a worthwhile upgrade for the minimal effort involved.

Nice writeup.
 

Cameron

ドクターマリ&#
Joined
Dec 6, 2006
Location
Crawling around under the car
If I remember correctly the later cars have this setup from the factory. Starting sometime around 87? I think the relay is mounted under the dash somewhere.

I think you are right about that -- don't know when Volvo added it, but late 80s sounds right from my foggy memory banks. I've seen reference of it being located in the driver side footwell on the firewall but never seen anything about when that actually happened.

I pretty much deal exclusively in pre '86 240s so I haven't had the depth of experience in "new" 240s like I have in the older ones.
 

propav8r

F*ck Edgar
Joined
Jan 17, 2010
Location
Franklin, NC
I'll be doing this the next time I head home. I narrowly missed having a 240 "Char-Grilled Edition" because of an overloaded 30-year-old switch.

Edit// that grab handle shipped out today. It should be in your hands by week's end.
 

M.H. Yount

New member
Joined
Nov 1, 2008
Location
Charlotte, NC
I did the Stern upgrade on mine years ago. 2 relays per side (1 for lowbeam, 1 for highbeam circuit), 10 gauge wire. Virtually no current through stock switches/harness and no (measurable) drop between alt and bulb. With 100w bulbs on highbeams - it gives good light.
 

wennstroma

Active member
Joined
Apr 25, 2006
Location
Idaho
I spliced in the later style switch and relay on my early car while going through the wiring harness. Prevents accidentally leaving the headlights on too.

Even those tend to melt the relay holder and terminal around the "30" supply, so adding the relays (like Daniel Stern sells) is still a good idea to remove the load from the factory wiring.
 
S

smokeyfan1000

Guest
FWIW/FYI....On the later 240s(86-93), the "Main Relay" as the parts book calls it, which is the mod you've done...was moved around a little in the cabin area.

On my 1986 245 it was "under DS carpet, under the brake pedal lever area" on auto trans. My 91 244 it's behind the center console "behind the little tray area".

Maybe this helps someone looking for it on those models
 

Dome

New member
Joined
Dec 18, 2011
Location
Los Angeles
Reroute a couple wires?

When you say 'Reroute a couple of wires' do you mean existion or new? With the new wires and relay installed is there any old wiring that needs to be disconnected?

I have dim high beam on my 242DL 1984.

Thanks!

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:

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
 

tiredoldtommy

Active member
Joined
Mar 1, 2008
Location
Antlers, OK
I'd like to report that this little modification was well worth the effort. I ended up making a little octopus-like critter with the relay as the body with a few short wires hanging off of it. The longest wire is only about 8 inches long. I mounted the relay beside the dimmer relay and just unplugged and replugged wires.

My lights are much brighter now.

Thanks, Cameron!
 
S

smokeyfan1000

Guest
I'd like to report that this little modification was well worth the effort. I ended up making a little octopus-like critter with the relay as the body with a few short wires hanging off of it. The longest wire is only about 8 inches long. I mounted the relay beside the dimmer relay and just unplugged and replugged wires.

My lights are much brighter now.

Thanks, Cameron!

GOOD TO KNOW! Glad it worked out well for you . relays are neat little items......
 

turbochimp

New member
Joined
Nov 2, 2011
Hi - I am slightly electrically challenged - am I correct that I should just cut the 10ga yellow wire coming off the step relay and connect the new relay in between the cut section?

Thanks for patience with dumb questions
 

bobxyz

Board Member
Joined
Aug 29, 2014
Location
Boulder CO
Yes, exactly.

[On my '85, I left out the extra fuse since the headlight circuit wasn't fused originally and I was confident that my rewiring was correct and robust. YMMV]

My headlight switch connector before the relay mod - it was still working, but barely:
85-melted-headlight-switch-connector.jpg
 
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