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: July 30, 2021 CONTACT

D O M A I N S

Mysteries of the 240 Headlight Step Relay	Eliminate the 240 Step Relay
How to Remove Terminals	760-960 Headlight Relay
Headlight Relay Harnesses	Bosch Terminal Designations
Or go to the 240 Headlight Page

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

1975-85 240
This headlight relay was used in these early 240s.
PN 1307991 Headlight Step Relay.

1986-93 240
Later 240s also got the 1307991 step relay, but these cars were also fitted with a "MAIN" (in-dash) headlight relay.
Here's a look at the main headlight relay in the 240 center dash.

This relay one is found next to and to the LEFT of the power door locking relays, which can be seen in the photo.
This photo was taken with the entire dash removed. You should be able to get to it by removing the center air vents and 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.

Main Headlight Dash Relay, This relay exists as a MAIN headlight relay in the 1986-93 240, using Volvo PN 1324749 (or 1235013)
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 relay, replacements are avilable HERE:
https://www.prancingmoose.com/volvorelays.html#pickerrelay

Why did Volvo add this "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 early headlight switches would stop happening. It solved that problem, but then heat melt damage would sometimes begin to occur in the relay plug.
The reason for this melting is due to slow corrosion of the power contact point in this plug (the Red/Green wire is the power). This damage can happen slowly over many years. The corrosion will cause resistance in that power connection, which generates more heat. More heat causes more corrosion, etc. The cycle continues until things begin to get hot enough to melt like the photo at left. Not all main relay plugs have this happen, however most have some evidence of damage after 30 years. This condition eventually damages the power circuit to the point the relay loses power and fails to operate. Often making a repair can be as simple as cleaning the terminals and relay posts or replacing the bad terminal inside the plug and the plug too if it's melted bad.

HOW CAN THIS BE PREVENTED?
CLICK HERE for info on ACZP

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

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 30 years and my current 240 is way over 30 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 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 recommend that you smear a little anti-corrosive zinc paste on those connections.
Many people in the Volvo community gravitate toward Ox-Gard, which does a similar 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 alumunum 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 corrosion which may have already begun. Anti-Corrosive Zinc Paste (or 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 otherwise begin to form in that connection.

Ron 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.

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 is on the opposite side on the late relay. 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 relay from the housing. Then the internal relay portion can be turned 180 degrees and re-installed.
This literally takes 30 seconds.

Relay Function
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

Keep in mind that a 240 does not have an "All Flash" function.
With a 240, the high/low beam lever has TWO positions. So with your headlights ON, you can pull the lever back to the momentary position and it will alternate between low and high beams. With the headlights OFF, pulling the lever back will FLASH the high beams. A 240 does not have the capability to flash high and low beams all at once. It will only alternate between low and high or only flash the high beams.

240 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 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 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 can 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 1392900 and has been no longer available new for many years.
Used relays are showing up online for OVER $200!
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 1975-85 FACTORY HEADLIGHT WIRING

240 1986-93 (with dash relay) FACTORY WIRING

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

<<< 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.
1975-85 240

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 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 are some Volvo specific diagrams that have been available on-line for many years. These use the same principles:
http://www.vclassics.com/archive/relays.htm

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 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 $200!
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 below.

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 below

In the 1990 760 Greenbook, this "A-E" relay is described as the Headlight Relay.

Here's the "F" relay shown in the above diagram. This has the Bulb Failure function.

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 this book.
So at some time there was a transition from the black headlight relay shown above to a later relay (shown below), which has an INTERNAL bulb failure sensor.

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 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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