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Understanding 240 Headlight Relays

     UPDATED: March 17, 2021                       CONTACT       
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Eliminate the 240 Step Relay
Mysteries of the 240 Headlight Step Relay

How to Remove Terminals

If you have any comments or if you can improve this information, please feel free to email.

CONTACT


Unlocking the Mysteries of the Volvo 240 Headlight Step Relay.
And Test Procedure.
This step relay is rather special in that it has a LATCHING function. 
A latching function works like this: You can click and release a momentary button or switch (such as the 240 high/low beam lever) and the relay will then LATCH (or lock) in the ON or OFF position until the switch or lever is clicked again. For this 240 relay, one click latches it "ON" and another click latches it "OFF."  In a 240 the latch function is activated by a GROUND signal, which is created by the high/low beam lever.




I have also created the below PDF (same info as shown above).
https://www.davebarton.com/pdf/headlightsteprelay.pdf

How to Use Commonly Available Relays
  to
ELIMINATE your Volvo 240 Headlight Step Relay
This modification will accurately reproduce the functions of the original Volvo step relay.  It simply copies and can replace the Volvo step relay and connectors.
It does not eliminate any need or recommendation you may have for additional headlight relays to feed high current headlights if you have them. Feel free to add those if needed. 

<<< Here is the 240 headlight step relay that came in every 1978-93 240.  The original relay, PN 1307991, is still available as a new part, however as the years go by, they are getting to be more and more expensive.  As original Volvo 240 headlight step relays become more expensive or less common, here I am offering an alternative that you can assemble yourself to completely eliminate the Volvo 240 Step Relay and connectors.

This method uses two commonly available relays to accomplish the same functions. 



<<<
For those of you that are new to this, the step relay is found under your hood on the left inner fender. 

Here's a quick little rabbit trail for owners of SOME OTHER Volvo models:
760 and 960 Headlamp Relays

As an example of what can happen to the availability of 240 step relays, which I hope doesn't happen, these images below are of the headlight step relay found in a 1988-94 Volvo 760 and 960 series.  This relay is PN 1392900 and has been no longer available new for many years. 
Used relays are showing up online for OVER $100! 
If YOU can help, I would be happy to work out a similar solution to eliminate THIS relay.
CLICK HERE to see this separate section at the bottom of this page.
 



BACK TO THE 240 STEP RELAY
This is a bottom view of the 240 step relay plug connectors. Beginning in 1986, Volvo added the in-dash headlight relay that was wired between the dash ON-OFF switch and the step relay. This extra relay was added to take the high-current load off of the dash switch because the dash switch plug would melt from the heat.

To keep this as simple as possible, I have not included the bulb failure sensor in these diagrams. If you need to know, the bulb failure sensor is wired between the step relay (pin 56b) and the low beams.
240 1978-85


240 1986-93 (with dash relay)

Factory 240 Step Relay Circuits.
Wire colors may vary slightly depending on year.
15
BLUE
12V Battery (common with 81a).
81a
BLUE
12V Battery (common with 15).
31b
BROWN
Signal from high beam lever (negative ground switched).
56
YELLOW
12V output from dash headlight switch (or from headlight relay in 1986-93 240).
56a
RED/WHITE, RED
Dash high beam indicator light (RED/WHITE).  High beam headlamp (RED).
56a
RED
High beam headlamp.
56b
BLUE/WHITE
Bulb failure sensor. Then from bulb failure sensor to low beam headlamp.


LATCHING RELAY

<<< The first thing you'll need to eliminate the 240 step relay is one of these. They are easy to find. You can search for "LR35 relay" or  VW latching headlight relay. 
This is basically a copy of a VW headlamp dip relay.  Cost will be around $20. This is a special mechanical latching relay. It's latching function will be identical to what the Volvo 240 step relay does. 

NOTE: I have found no available connector plugs that will fit this relay.  Those pins are standard .250 inch (6.3 mm), so simple 1/4 inch crimp spade connectors will be fine.



STANDARD MINI RELAY
1235893 Volvo Tyco Brown Relay

<<< You will need one standard mini "cube" relay for this project. 

This relay can be an SPST type as shown in these images.  40A capacity is recommended.
SPST means Single Pole, Single Throw.
An SPST relay will usually have 5 pins, with the center pin marked 87b (or sometimes just 87).

With this type of relay, pins 87and 87b are common and both give power at the same time.  You may also use pretty much any other standard relay, since for this project, the center pin is not being used.  If you need a relay like this, I offer this brown relay in my relay page at: https://www.240turbo.com/volvorelays.html#1324749-006brown.



DIAGRAMS

To help you understand how this new device will work, let me show you a simplified diagram showing the functions of the two replacement relays involved. This is a bottom view of the new latching relay and new mini relay. Beginning in 1986, Volvo added the in-dash headlight relay that was wired between the dash ON-OFF switch and the step relay. This extra relay was added to take the high-current load off of the dash switch because it would melt from the heat. 

I have not included the bulb failure sensor in these diagrams. The bulb failure sensor is wired between the latching relay (56b) and the low beams.
1978-85 240


1986-93 240



When this mod is done, the original step relay and connector plugs are eliminated, but for illustration value, here's a diagram that shows the pins in the original Volvo step relay connector and how they relate to each circuit on the two new relays.

The latching outputs in the new latching relay are poles 56a and 56b. These two outputs will alternate power with each tug of the high beam lever.

Here's a link to a page created by a 245 owner who did this mod for his car in 2017. He also added relays for his high and low beams, as well as driving lights.
https://brokedownbrick.wordpress.com/2017/11/21/headlights-and-under-hood-power-distribution/

 
Here's a printable PDF document that covers the above step relay modification.
Click on the image for 2-page PDF.
If you have any comments or if you can improve this information, please feel free to email.
CONTACT

 
How to Remove Terminals from Original 240 Step Relay Plugs

 Here we have a typical relay socket plug used in Volvos.  NO, This is NOT really a step relay socket plug , but it'll work for this demonstration.  
Notice the metal terminals inside the holes? Not all the holes always have terminals.


You'll need a tool for this part... a long sharp pick will do. A micro screwdriver can also be used. If your tool is not small enough on the tip, a little grinding will fix it as I did on this pick. Even a stiff piece of piano wire can work for this step.
 

Now pay attention to the little openings at the top of the little rectangular holes. That wide spot is where you need to insert your pick. The idea is to insert the pick in about 3/8 inch (10 mm) or so and push down to flatten the locking tab on the terminal. That locking tab holds the terminal in the socket. In the next photos, the locking tab will be easy to see.


If your socket doesn't have a wider opening that you can see, just pay attention to the below pics to know which side of the terminal to insert the pick into to push on the tab.


In this photo you can see the terminal backing out of the hole after the locking tab was released.


Here's a good view of the locking tab on the crimp terminal. After you depress and release the tab and pull the terminal out of the socket, you may find that your tool bent and flattened the tab a bit too much. If you will be re-inserting this terminal into a connector, the tab may need to be pushed back out so it still engages when re-inserted. It needs to be sticking out like in this photo to work correctly. If you accidentally break the tab off, you'll need to crimp on a new terminal.

And make sure the locking tab is on the correct side of the socket hole when re-inserting. As it gets inserted, you should hear a 'click' which tells you it has locked into place. Always make sure by giving the wire a little tug.

And always pay close attention when you plug sockets like this back in to see if any terminals get pushed back out. That can happen sometimes if the tab hasn't fully locked the terminal in place.






760 and 960 Headlamp Relay
As an example of what can happen to the availability of 240 step relays, which I hope doesn't happen, these images below are of the headlight step relay reportedly found in (approximately) 1988-94 Volvo 760 and 960 series. 
This relay is
PN 1392900 and has been no longer available new for many years. 
Used relays like these are showing up online for OVER $100! 
If YOU can help, I would be happy to work out a similar solution to ELIMINATE THIS RELAY in a similar way as the 240 relay. I need help from someone out there with one of these cars and maybe someone willing to lend me a relay like this for some testing.
So far very people few have spoken up.

CONTACT ME if you can help with this.

PN 1392900
 
  

And there is also apparently a
Canadian version of this relay. This photo was sent by Jesse W.  The extra Pin #15 is thought to be for Daytime Running Lamps (DRLs) that were required in Canada.
PN 3523535



In the 1990 760 Greenbook, this "A-E" relay is described as the Headlight Relay. The "F" relay shown above to the right is the Bulb Failure Relay.
In the 1994 960 Greenbook, the same "A-E" relay is pictured and described as the Headlight Relay with Bulb Malfunction Indicator. No "F" relay is shown in that book.
So at some time there was a transition from the black headlight relay shown above to a later relay, which has an INTERNAL bulb out sensor. 
This can get confusing and it needed more studying. What I found is that if you have a similar headlight relay, but it has a pin labeled "K", then you will know your relay has an internal bulb failure sensor. If not, then your relay is designed to use a separate bulb failure relay. The "K" pin is the power output to activate the dash 'bulb failure" light.

Here are the USA/Canada HEADLIGHT and FOGLIGHT diagrams for the 1990 760.
CLICK FOR HI-RES IMAGE.
 

Here are the USA/Canada HEADLIGHT and FOGLIGHT diagrams for the 1994 960.
CLICK FOR HI-RES IMAGE.
 
This is a Volvo headlight relay that uses an internal bulb failure sensor.







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