Creating a Volvo Headlight Relay

2 4 0 T U R B O . C O M
D A V E ' S V O L V O P A G E

240 Headlight RELAY Page

UPDATED: January 14, 2024 CONTACT

D O M A I N S

Go to the 240 HEADLIGHT Page
Mysteries of the 240 Headlight Step Relay	Eliminate the 240 Step Relay
240 Headlight Circuit and Function Diagrams
How to Remove Terminals	760-960 Headlight Relay
Headlight Relay Harnesses	Bosch Terminal Designations
Dealing with the 240 Bulb Failure Sensor

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

Before 1975 (before the 240)
This early headlight step relay was used in the 140 model for headlight control and 1800 models for overdrive control. It's function is similar to the headlight step relay shown below.
More about this relay can be found in Ron Kwas' page: https://www.sw-em.com/Headlight_Notes.htm#Bistable_Control_Relay

1975-85 240
This headlight relay was used in these early 240s. It's function is to switch (or step) between low beams and high beams. It's a big relay and it makes a loud "clunk" when it switches. It's generally a very reliable relay.
The internal function of this relay is COVERED IN DETAIL HERE.
PN 1307991 Headlight Step Relay.

Sometimes these relays fail. I had one fail one time many years ago. The failure was an internal soldered junction that broke, which disabled low beams. I was able to disassemble it and I repaired it with a soldering iron.

1986-93 240
Later 240s beginning in 1986 also got the 1307991 step relay, but these cars were also fitted with a new "MAIN" (in-dash) HEADLIGHT RELAY.

Here's a look at the main headlight relay in the 240 center dash.

This relay is found NEXT TO and to the LEFT of the POWER DOOR LOCK RELAYS, which can be seen in this photo above.
This photo was taken with the entire dash removed. Removing the dash is not necessary to access these. You should be able to get to these relays by removing the center air vents and by pushing the inner plastic air duct out of the way. Or by removing the center dash console as shown in the below VIDEO. No, Volvo didn't make it very easy to access these.

240 Relay Locations PDF below (1993 diagram). Look for Relay 124 Main Headlight Relay.

Main Headlight Relay (in dash). This relay exists as a MAIN headlight relay in the 1986-93 240, using Volvo PN 1324749 (or 1235013)
Relay is the same as Bosch PN 0332015001, 0332015006, or 0332015012.
Beginning in 1986, Volvo added this "main headlight relay" to the 240. Prior to this the 240 used only the dash switch to turn on the headlights and then the well known high/low beam step relay under the hood. This "main" headlight relay is a mystery to many 240 owners, because it's tucked away out of sight under the dash.

This relay typically fails more often than the under hood step relay.
The most common failure is at the power connector on the relay plug, which can become burnt/melted (more info below).
If you need one of these relays, replacements are available HERE:
https://www.prancingmoose.com/volvorelays.html#pickerrelay

Why did Volvo add this 1986+ "MAIN" headlight relay?
Volvo added this relay to the 240 to take the heavy current load away from the dash headlight switch, so the heat-melt damage typically found in MOST early headlight switches would stop happening.
Much more detail about the headlight switch problem is found in the Headlight Page HERE.

This relay solved that switch problem, but then heat melt damage would sometimes begin to occur in the relay plug as seen in this photo.
The reason for this damage is due to slow build-up of corrosion on the power contact point in this plug (the fat Red/Green wire is the power wire).
This damage happened slowly over many years. The corrosion will cause resistance in that power connection, which generates heat. More heat causes more corrosion, etc. The cycle continues until things begin to get hot enough to melt things. Not all main relay plugs have had this happen, however most I've seen have some evidence of damage after 30 years. This condition mainly affects the plastic plug, but it can eventually damage the relay. Often making a successful repair can be as simple as cleaning the plug terminals and relay posts or replacing bad terminals inside the plastic plug. Replacing the plug too is a must if it's melted bad like the one pictured.
HOW CAN THIS PROBLEM BE PREVENTED IN THE FUTURE?
CLICK HERE for info on ACZP

Here's a nice video showing how to locate and change this center dash main headlight relay:
https://www.youtube.com/watch?v=G9wftGCBWXc

240 HEADLIGHT CIRCUITS AND FUNCTION DIAGRAMS

I created this detailed 1984 function diagram below in 2023 so that almost ALL circuits and connectors and all connector pins can be seen. Please email if you have any questions or corrections.
Click image for larger, high-resolution photo.

I created this detailed 1986 and later function diagram below in 2023 so that almost ALL circuits and connectors and all connector pins can be seen. Please email if you have any questions or corrections.
Click image for larger, high-resolution photo.

ANTI-CORROSIVE ZINC PASTE (ACZP)
If we can just just keep our electrical connections clean and tight, almost all of the electrical issues would be gone forever. That would be nice, right?

I have owned a number of Volvos over the last 35 years and my current 240 is 40 years old. It almost never has electrical problems. Nothing like the endless numbers of other 240s out there that I hear about so often. What's the difference you ask? The main difference is that my 240 has been always garaged all of its life. Why is that important? Because leaving any car out in the open elements for years and years slowly introduces corrosion to grounds and power connections until things begin to go wrong.
So if you own one of those cars that has been outside forever, it's not too late. You can still clean as many grounds and electrical connections as possible.
And while you're at it, I strongly recommend that you smear a little anti-corrosive zinc paste on those connections.
Many people in the Volvo community are already familiar with Ox-Gard, which does a very good job.

The below information was contributed by Ron Kwas and should come in very handy to old Volvo owners:
Anti-Corrosive Zinc Paste (a generic name for zinc dust contained in a grease) was originally developed for and later required by electrical codes for use on aluminum to copper electrical connections (or other dissimilar metal connections). No, it's not the same as Dielectric Grease, which is often incorrectly recommended. Dielectric Grease can offer some protection in the form of encapsulation from moisture, but it also carries with it the potential disadvantage of locking in moisture or existing corrosion which may have already begun forming. Anti-Corrosive Zinc Paste (ACZP) is the next evolution of the encapsulation principle, because zinc (the lowest on the Galvanic nobility chart) neutralizes corrosion on a micro-scale to truly protect connections on a long-term basis during the encapsulation, INCLUDING an added protection from corrosion which may have begun to form in that connection.

Ron Kwas uses and recommends Penetrox A (by Burndy). Many Volvo fans are familiar with Ox-Gard, which is a similar zinc compound. Ron and I are huge advocates of treating ALL electrical connections on our cars (except of course High Voltage Ignition connections) with a suitable version of this material.
You can learn more about this stuff at Ron's page here:
http://www.sw-em.com/anti_corrosive_paste.htm

Unlocking the Mysteries of the Volvo 240 Headlight Step Relay.
And Test Procedure.

VOLVO PN 1307991.
This step relay is found in the Volvo 240 from 1975 to 1993. It will be seen under your hood on the left inner fender, except for the 1993 model, where it was switched to the RIGHT inner fender.

This relay was made in two different versions (same part number), however both versions function exactly the same and both are interchangeable.
The EARLY version can be identified below with two less contacts. The extra contacts in the LATER version do not change the function at all. It just adds redundant contacts.

Regarding these early or later relays being interchangeable, THEY ARE, however keep in mind that if you use an early relay on a later car AND your car just happens to use those extra two contact pins, you'll need to re-wire those contact pins to the two outside pins.

MOUNTING BRACKET CHANGE
If you're observant, you'll notice that the mounting bracket on a later relay is on the OPPOSITE SIDE. This doesn't affect the function, but it might affect the harness plugs, because if you use a newer relay in an older car, the harness plugs will need to be twisted 180 degrees to work. That will add unwelcome stress on your wires.
A simple solution is shown below.

It's a very simple task to pry open the crimps and remove the top outer housing. This is NOT hard to do. Then the housing can be turned 180 degrees and re-installed onto the relay bottom.
This literally takes 30 seconds.

Step Relay Latching Function Explained
This step relay has a LATCHING function. A latching function works like this:
You can click and release a momentary button or switch (in this case it's pulling back on the 240 high/low beam lever) and the relay will then LATCH (or lock) in one position or another. It reverses with each pull of the lever.
So with this step relay, one click latches "ON" the low beams. And another click latches "OFF" the low beams and latches "ON" the high beams.
In a 240 the latch function is activated by a GROUND signal, which is created by pulling the high/low beam lever.

Here's a short video on the step function between high and low beam.

https://www.youtube.com/watch?v=Nwb485qhWtA

ALL FLASH function? No!
Keep in mind that a 240 DOES NOT have an "All Flash" headlight function.
With a 240, the high/low beam lever has TWO "click" positions. So with your headlights ON, you can pull the lever back to the momentary position and with each pull it will alternate between low and high beams.
With the headlights OFF, pulling the lever back to the momentary position will FLASH the high beams. High beams only. A 240 does NOT have the capability to flash high and low beams all at once.
Your only choices will be:
1. Alternate between low and high.
2. Or flash the high beams.

240 Step Relay Function and Testing

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

How to Use Commonly Available Relays
to ELIMINATE or REPLICATE 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.

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. Someday they will become too expensive or maybe even extinct. As original Volvo 240 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.

Here's a quick little rabbit trail for owners of SOME OTHER Volvo models:

760 and 960 Headlamp Relays

As an example of what could happen to the availability of 240 step relays someday, these images below are of the headlight step relay found in a 1988-94 Volvo 760 and 960 series. This relay is PN 1362900 and has been no longer available NEW for many years.
Used relays are showing up online for OVER $200!
I have been working out a similar solution to offer a way to eliminate THIS relay.

CLICK HERE
to see this separate section at the BOTTOM of this page.

BACK TO THE 240 STEP RELAY

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. If you need detailed info about the bulb failure sensor, go to: https://www.240turbo.com/volvo240mods.html#bulbfailsens1

240 1975-85 FACTORY HEADLIGHT WIRING

This is a bottom view of the 240 step relay plug connectors.

240 1986-93 (with in-dash headlight relay) FACTORY WIRING

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 often melt from the heat.

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 complete this project is one of these. They are easy to find. You can search for "LR35 relay" or “VW latching headlight relay.”
It's also available as Porsche PN 111941583. The aftermarket versions are basically copies of a VW/Porsche headlamp dip relay. Cost will be around $20 to $30. This is a special mechanical latching relay. The latching function is identical to what the Volvo 240 step relay does.

NOTE: I have found no available connector plugs that will fit this relay. Those male pins are standard .250 inch (6.3 mm), so simple 1/4 inch crimp spade connectors will be fine until something better is found. Feb 2023 update on that: https://turbobricks.com/367210

STANDARD MINI RELAY

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

This relay can be an SPST type as shown in these images. The original Volvo relay had a 30 amp rating. 40 amp capacity relays are easy to find too, so I recommended upgrading to 40 amp.
SPST means Single Pole, Single Throw. An SPST relay will usually have 5 pins, with the center pin marked 87b (or sometimes just 87). The center pin is not used in this project.

With this type of relay, pins 87 and 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.

1975-85 240

1986-93 240

When this mod is done, the original step relay and connector plugs can be eliminated, but for illustration value, here's a diagram that shows the pins in the original Volvo step relay connectors 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 Headlight Step Relay Plugs

 Here we have a typical relay socket plug used in Volvos.  NO, This is NOT really a headlight 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.

Headlight Relay Harnesses

This is a good project for anyone with any older Volvo, especially if you have or want to to upgrade to brighter bulbs or headlights.
For the best info I know, begin reading Daniel Stern's page on this subject. He also has several useful diagrams for designing and building your own relay harness.
http://www.danielsternlighting.com/tech/relays/relays.html

Here is a Volvo 240 specific diagram showing how an upgraded relay harness can be made. The relay triggers (relay are connected to and triggered by 56a and 56b) can be taken from the fender harness connectors or if you want to bypass the bulb failure relay, you could take those triggers from terminals 56a and 56b directly from the 5-pole headlight step relay connector.

This diagram assumes you would use one relay to control both low beam headlights and another relay for the high beams.
The above 9004 bulb socket came on all 1986-93 USA 240s. A European E-Code headlight will typically use an H4 bulb.

UPDATE 2018:
Wagonmeister is offering ready made 240 headlight relay harnesses, like this one below.

760 and 960 Headlamp Relay

As an example of what can happen to the availability of unique step relays, which I hope doesn't happen to the 240, this below is the headlight step relay found in (approximately) 1988-94 Volvo 760 and 960 series.
This "A-E" relay is PN 1362900 and has been no longer available new for many years.
Used relays like this one have been known to show up online for OVER $200!

My goal was to work out a similar solution to offer a way to ELIMINATE THIS RELAY in a similar way as the 240 step relay can be eliminated.

PN 1362900 relay below.
This relay does not have an integrated Bulb Failure Sensor function inside (some later versions do).

And there is also apparently a Canadian version of this relay, PN 3523535. This photo ABOVE was sent by Jesse W.
The relay is the same as 1362900, except for the extra Pin #15 above, which is thought to be for activating Daytime Running Lamps (DRLs) which were required in Canada.

In May 2023, Jesse F. sent me a 1362900 relay to test. The info below will outline the results.

The connections ABOVE demonstrate how I was able to get this relay to function. Take note that the STEP function of alternating between high and low beam will only function after the relay receives power from the headlight switch (in the 'ON' position). So you might ask, how does the high beam function work when the headlight switch is OFF? It works because the high beam switch bypasses this relay when the lever is pulled to the 'FLASH' position. Power to the high beams in this situation comes directly through the high beam switch and goes directly to the high beams, not through the headlight relay.

What about the second set of contacts (56, 56a and 56b) at the bottom?
Those are duplicates of the top contacts. Their functions are not totally clear, but I suspect they feed to the fog light switch or the bulb failure sensor. Either way, they have no affect on the STEP relay function.

1362900 Internal Image

Then I created a VIDEO below of the test result.
Activating the step trigger (which replicates activating the high-low beam lever switch), will cause the two coils to alternatively connect. This action creates a closed circuit which alternates from low to high beam. If you watch closely, you can see the coil contacts move alternately. If you blink you'll miss it.
https://youtu.be/M1f1ZiFJZhI

RESULTS

The above image is meant to show SIMPLIFIED circuits needed to operate a universal latching relay and mini relay in the 740. These are the same two relays used in the 240 diagrams in this page.
Resources for locating these two relays CAN BE FOUND HERE.

HERE IT IS.
GUIDE FOR DELETING THE ORIGINAL 1362900 RELAY
The below diagram is meant to show the NEW CIRCUITS you can add between the 740 relay socket (with original relay removed) and these two replacement relays. I didn't have a 740 to actually try this out, but Chris V. in Dallas did this mod to his 1990 760 and has confirmed it is again working as it should. Feel free to email me if you have any comments questions or feedback.

Simple MALE 6.3 mm terminals like this below can be used to insert into the empty relay socket slots.

CONTACT ME if you have a comment.

Other Related Relays

In the 1990 760 Greenbook, the "A-E" relay above is described as the "Headlight Relay." As mentioned above, this relay does not have a Bulb Failure Sensor function (which is found in later relays). The Bulb Failure function in the above car is done separately by the yellow "F" relay shown in the above images and also in the below photo.

Here's the "F" relay shown above. This "F" relay serves as the Bulb Failure Sensor.

Later Relays. Bulb Failure Sensor function was integrated into the Headlight Relay.
In the 1994 960 Greenbook, the "A-E" relay is pictured and described as the Headlight Relay with Bulb Malfunction Indicator. No "F" relay is shown in these diagrams, so by 1994 there was a transition from the black 1392900 headlight relay to a later (yellow relay shown below), which has an INTERNAL bulb failure sensor function.

This can get confusing (especially for me, since I don't have one of these cars) 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. This High/Low Beam diagram shows a headlight relay and a separate bulb failure sensor.
CLICK FOR HI-RES IMAGE.

This is a later Volvo headlight relay that uses an INTERNAL bulb failure sensor.
Note the "K" terminal mentioned above.

Here are the USA/Canada HEADLIGHT and FOGLIGHT diagrams for the 1994 960. The high/Low Beam diagram shows a headlight relay with "K" terminal, noting the internal bulb failure sensor.
CLICK FOR HI-RES IMAGE.

Note from Simon W. in Hawthorn, Australia (July 2021)
"Thank you for your wonderful website. You asked for comments about relays, in particular the AE which is a classic I'm sure you know, controlling the high beam and low beam headlights. As you said there are profiteers who want $300 for used one so it pays to keep them going."

"Mine was was driving me crazy, would not turn on low beam, but fine on high beam and on close inspection of the mechanism inside the case, I noticed a tiny pad missing from the contact on the low-beam solenoid. There were signs of arcing, consistent with the intermittent nature of the fault. Sometimes the lights would turn on but mostly not."

"I tried a mod on one of the low-beam solenoid contacts, the one missing its little pad, simply bending the end slightly and voila! It worked, lights back in business."

"They said it was a sealed unit which of course is untrue. They are made by Hella, old school, solid copper and even an amateur like me can figure out how they work."

"The 960 wagon is quite rare here but I love it's versatility and the smooth straight 6 engine. So it's great to keep it going with such a simple solution."

Bosch Terminal Designations

If you've ever wondered where all of those relay and component terminal numbers came from, they were standardized by Bosch and a list of those numbers and their meanings can be found at the following link:
http://dastern.torque.net/techdocs/boschterm.html

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