Emergency Flasher Retrofit for 122/1800    
first posted 6/99 R. Kwas, revisions on-going!  [Comments added]

Add-On Emergency Flasher Switch Location
SWF Emergency Flasher Switch
Emergency Flasher Upgrade Procedure (122/1800)
    Reference Information:  Nesan Emergency Flasher Switch
Retrofitted E-Flasher Switch in a 122 using the Nesan switch
Directional Indicator ORing Diode Modification
Retrofitted E-Flasher Switch in an 1800 using the SWF switch
Notes on Making In-Line Connections

Additional Information: 

Knob of SWF Switch disassembled
Practical Experience Adding Emergency Flashers 122

Details on Emergency Flasher Variation in late production 122



This article consists of notes on the subject and installation procedure for retrofitting an Emergency Flasher switch.  We occasionally have a O.E. switches (used), as found on some 1800s and early 140s, and seen in picture below available.  As these are getting more difficult to find, I am trying locate and stock other good option(s), see further below. 

Background:  In the late '60s, the Emergency Flasher (also sometimes known as: Hazard or Four-way Flashers) came into general use on new vehicles.  By tying both right and left directional indicator circuits together, the Emergency Flasher was created, giving the car double the visual impact when activated.  The original equipment Emergency Flasher switch was really an add-on, installed typically on late production 122s and 1800s by the stateside dealer, who mounted it (not particularly attractively) below the dashboard,  sometimes the right side, sometimes on the left of the Steering Wheel, as in the case shown below, when an Air Conditioning unit was fitted. 

Add-On Emergency Flasher Switch Location:

Picture source:  Fredrik Lofter's site.

Given the miniscule size of Directional Signals compared to later cars, it is a very worthwhile safety upgrade to retrofit a vintage Volvo with this feature.  Shown in the picture below, is one of the switches as used in early 140s (by German manufacturer SWF, with all wires removed, except the three required for a retrofit installation).  These quality switches had their own Blinker Element, and a knob with an indicator lamp very similar in appearance to those of the 122 and 1800, so will fit in nicely.

140 style Emergency Flasher switch by manufacturer SWF. 
A three terminal Blinker Element is shown in place, plugged onto the back.


In order for the switch to be instantly accessible, and to make for a nice, neat, O.E looking installation, I have successfully installed the switch in place of the cigarette lighter on both 122s and 1800s.  The 1800 installation shown below is in a new hole - the Lighter hole was already used for auxiliary lighting  and not available. 


Emergency Flasher installed in former cigar lighter hole 122S.


Emergency Flasher installed in a new hole in an 1800.


When installing the switch, the amount of room available behind mounting is an important consideration...at 3 3/4" deep behind the dashboard because of that Blinker Element, these switches are fairly long, and so won't fit just anywhere.  Measure twice before cutting metal to prevent clearance disappointments! 

SWF Emergency Flasher Switch:

SWF PN500.298 Switch and (3 terminal) Flasher Element side-view. 
Lighted Knob in ON position.  Blinker Element installed. 


Lighted Knob in ON position.  Blinker Element removed.

Link to:  Additional Information:  Knob of SWF Switch disassembled.


Switch and Flasher Element, business ends, allowing
detailed inspection of terminal numbering and designations. 

See also:  https://www.sw-em.com/Blinker_Relay_or_Element.htm#Three_Terminal_Blinker_Element_in_the_Fuel_Injected_1800    


Emergency Flasher Upgrade Procedure (122/1800, using the 140 Style Switch):


This procedure has been prepared with the utmost care. However, it is strictly a guide to be used in conjunction with normal, cautious shop practice.  I cannot accept liability for all your actions (especially the part where you drill through your thumb!).  Work Safely!

Special tools required:  140 style Emergency Flasher Switch, various Crimps and Crimping tool,  7mm or 9/32" nut driver.

Refer to electrical diagrams:  122 Wiring Diagram, 1800 Wiring Diagram

1.  Prepare switch wiring:  Remove all wiring except for a Blue wire on L terminal, a Green wire on R terminal, and a Red wire on terminal 30. 

Internal connection details of the 140 style Emergency Flasher Switch
SWF PN500.298 with Blinker / Flasher Element. 

2.  Disconnect vehicle Battery before proceeding.

3.  If mounting the Emergency Flasher Switch in hole originally intended for cigarette lighter, remove lighter, disconnecting power wire from back of lighter, and using nut-driver at back of ignition switch, removing other end of this wire from terminal 54 (Ignition Power).  If not replacing lighter, do not touch its' power wire.  In both cases, connect the red wire from Emergency Flasher Switch terminal 30 to terminal 30 (Battery Power) of ignition switch (has heavy black wire and possibly others).  Include an in-line fuse-holder with a fuse rated at 10A. 

4.  Mount switch.  Be aware, switch is 3 3/4" long behind panel.  If mounting in former cigarette lighter hole, washers should be used to center the switch as well as keeping it from falling through the (much oversized) hole.  The switch bushing also requires a good electrical connection to the dashboard sheetmetal, as it is the ground return current path for the indicator lamp in the knob.

5.  Locate Wires [on a 122 - Blue (left directional signal circuit)  and Green (right directional signal circuit) - on a 1800  Green/Red (left directional signal circuit) and Green/White (right directional signal circuit)] under dashboard [located by steering column harness (make careful incision through sleeving to gain access), or at connector (in case of 122) or harness (in case of 1800) of wires which run up A pillar, over roof and to rear of vehicle] and connect to these, by first cutting, then using butt crimp and suitable crimp-tool to reconnect wires, adding the appropriate wire which route to emergency flasher control switch (see also:  Notes on Making In-Line Connections below).  Route wires along existing harnesses taking care to stay clear of moving linkages under dashboard such as wipers and steering column. 

6.  Double check wiring, resolve any items of question before proceeding. 

7.  Reconnect vehicle Battery. 

8.  Verify operation of Emergency Flasher control.  Note: The indicator lamp in the knob should flash, but the instrument panel directional indicator will not.  

[Comments on this procedure are welcome] 


Addendum for 544 / 210 or even 444 / 544 (6V) vehicles.

Although I haven't personally upgraded one of these vehicles, it is certainly still a very good idea. 

Refer to Wiring Diagrams:  544/210 Wiring Diagram, 544 (6V) Wiring Diagram, 444 (6V) Wiring Diagram.

From the 544/210 and 544 (6V) and 444 wiring diagrams, the color codes are similar to the 122...Green for Left, Blue for Right directional circuits, and these wires should be easily accessed at harness going to the directional indicator. 


Reference Information:  Nesan Emergency Flasher Switch 

As the 140 style switches have been getting more difficult to find, I have started looking for a reasonably priced, similarly styled alternative...what I found as a possibility, is a Nesan switch (Made in Turkey, from what looks like probably originally a German design) with a similar looking lighted knob, shown below.   This switch does not have a separate Blinker Element associated with it, so wiring it into a vintage Volvo is a bit more complicated as it needs to use the existing Blinker Element (this means seven total wires instead of just three as with the 140 style switch!), but the switch has the necessary contacts and switching function that it will work out well. 

I am looking into stocking these switches...it looks like a quality component, but I will pass my final judgment once I get one in my little hands to inspect.  Please e-mail to check availability. 

UPDATE:  The Nesan switch is of decent, usable quality, but no-name clones are now on the market...I was way less than impressed, actually borderline appalled by their construction and internal quality...these clones are typical china-shit product which looks just like the real thing, but is utter TRASH!  Buyer Beware!

NESAN Emergency Flasher Switch.  Accept no copies!

Below is a marked-up copy of the 122 Wiring Diagram incorporating this switch.  The color of wiring at switch shown in the mark-up below would be my suggested colors, as they are consistent for the most part, with harness colors.  Note that original Red wire at Blinker Element must be cut as shown.  Simple butt crimps should be used to connect the E-Flasher Sw wiring to these cut ends.  I recommend butt crimps for the in-line taps on other wires also, see:  Notes on Making In-Line Connections below

 I have left the file large so that it can be copied and printed with high detail for reference while carrying out the work.

Retrofitted E-Flasher Switch in a 122 using the Nesan switch (uses the existing Blinker Element):   

Notes on Circuit Function:  In the OFF position, upper part of switch routes Ignition Power to Blinker element normally, and L and R circuits, connected to lower part of switch, are separate and not connected to each other.  When switch is placed in the ON position, upper part of switch powers Blinker element by Battery Power, by way of in-line fuse (recommended), lower part of switch ties L and R circuits together, and to output of Blinker Element, as well as Indicator in the knob.   

Emergency Flasher can be used at any time (as it should be able to), since it is powered by Battery...Ignition ON or OFF, and Indicator lamp in knob will flash along with Directional Signal lamps at vehicle corners.  Normal Directional Indicator in Instrument Panel will not flash along when E-Flasher is activated, unless the Diode Modification shown below is also made.  This also applies to the 1800 installation below. 

Directional Indicator ORing Diode Modification: 

The original Directional Indicator in the Dashboard is of a single lamp design, that is, it uses the unpowered side lamps as the chassis return path for the powered side, thereby applying power across the indicator lamp (when signaling right, current in indicator lamps flows in one direction, when signaling Left, in the other direction!).  This is a clever solution which allows use of a single indicator to show two separate functions.  However, this clever solution does come with drawbacks, which make themselves known under two conditions. 

1.  The "Clever Solution" will not function with an E-Flasher switch installed, since both Right and Left side indicator circuits are tied together for the E-Flasher function.  By definition, when the two circuits are tied together, there is no voltage difference between them necessary for the "Clever Solution"!...but a simple modification is possible!  In order to allow the Directional Indicator to blink along with E-Flashers, a Diode ORing circuit modification can be added as shown here: 

Original configuration showing direction of current flow through Blinker Indicator.  With Diode Modification, Blinker Indicator power
 can be powered by Right and Left circuits normally, OR both when tied together by E-Flasher Switch.  This circuit change makes current
 flow in only one direction in Blinker Indicator, so also would allow the option of making it an LED.

2.  Since direction of current flow in the "Clever Solution" changes, this solution also has problems (doesn't work!) when LED lamps are installed for the Directional Lamps!  Recall that LEDs have a specific and only one direction of current flow...an incandescent lamp (like the Directional Indicator in the Instrument Panel) doesn't care!  

The finer optical points which must be considered with LED installation are covered here:  https://www.sw-em.com/Amazon_Rear_Light_Fixture_Restoration.htm#Considering_LED_Replacement_Lamps 

The finer electrical points which must be considered with LED installation are covered here:  https://www.sw-em.com/Blinker_Relay_or_Element.htm

See also:  Practical Experience Adding Emergency Flashers 122


Retrofitted E-Flasher Switch in an 1800 using the SWF switch with its own Blinker Element (vehicle will have a total of two Blinker Elements after this modification, but this is not a problem...the one associated with E-Flasher Sw will be just along for the ride most of the time...!):  

Notes on Circuit Function:  As the Emergency Flasher Switch has its own Blinker Element, all it needs is Battery Power from Ignition Switch Terminal 30 and connection to the Right and left Blinker circuits.  Three wires (plus a good connection to the mounting panel to return the Indicator current), but that's it! 

Flasher will of course be available any time, but if switch is engaged with Ignition ON and also one of the Directional Indicators, there may be some weird timing of Flashers as they are powered by two sources interacting, but nothing will be damaged...simply turn off the engaged Directional Indicator and the Emergency Flashers will blink at the corners as expected.


Link to Consideration of the Emergency Flasher and associated in an 1800ES:  Four Terminal Blinker Element in the 1800ES
Here, the E-Flasher was a factory installed function, so it is not so much a "retrofit" situation, but much can be learned by studying this factory installed feature. 


Notes on Making In-Line Connections:

It's always preferable to make connections to wires at an end using a Paralleling Terminal.  Two options which retain the positive mechanical advantages are see here:

Paralleling Terminals

...but sometimes, [as with retrofitting an Emerg. Flasher] this is just not practical or possible...so when making the necessary connections to existing wires in the middle of a run, or in-line, for a reliable connection, crimp connection to the middle of an existing cable.  I recommend using butt crimps to restore the connection, and adding the new wire.   Best practice when crimping a wire is to cut, and strip the wire, apply ACZP to the stripped strands, and crimp them into a proper butt crimp of the correct size-range for the wire gauge (taking into account that the one side will have more strands because of the added wire), using a quality crimping tooland/or technique (see:  http://www.sw-em.com/Wiring Notes.htm#Crimp_terminals_Tools_and_making_a_Proper_Crimp  )...of course, when I want the absolute best and most permanent, reliable crimped connection I can make, I solder it !! (then protect with heat shrink tubing)...because there's just no beating a Gas-Tight-Joint!  See also:  740_harness_meltdown.htm#permanent_wiring_repars

I recommend very much against the Scotchlok clip-on, Insulation Displacement Connectors (IDC) shown below, also known amusingly as "Strom-Diebe" (Current-Thieves) by the Germans (maybe because it reminds them of the way we tapped into the Russian's telephone line running under East Berlin during the Cold War.  See the fascinating story of:  Operation Gold  or Turning a Cold War Scheme into Reality   ...in any case, see below for my explanation of why these are a "Scourge upon the automotive electrical land!", and should never be used.

...because I totally agree with it, I will also show this picture I saw on Bill Pollack's site...: 

Excerpt from my entry on Tom Bryant's Blog:  https://thosbryant.wordpress.com/2014/06/28/saturn-fuse-box-repair-1998-1999-redux/
 (yellow highlights are not a part of my original post but added for emphasis):

"I don’t agree with your positive assessment of the “Clip-On” [Schotchlok] connectors you show. They work by cutting and displacing wire insulation. Unfortunately, they also cut into the conductor (they’re actually designed to, with a sharp edge and an undersized slot for the conductor), so they are also damaging the conductor and decreasing its cross-section (BAAAAD) [to say nothing of the potential damage in the form of stress-riser they are without a doubt adding to the conductor...and that in a vibration environment!!  Egad!!]. They are merely OK (short-term) under laboratory conditions only (clean, dry, non-moving), but in a vehicle (and long-term), the connection they make is totally susceptible to moisture, and vibration – at least!  I REFUSE to use them…I throw them out (and I don’t throw ANYTHING out), and I replace them when I run across them. 

Again my rule is: If I want the BEST crimp connection I can get…I SOLDER IT(!), so functionally, I’m OK with your solder/shoegoo technique of adding a connection in the middle of a wire, but for a cleaner final appearance, I would use heat-shrink tubing immediately over [freshly applied] silicon RTV (which had not cured). As the tubing shrinks, it compresses the fluid RTV around the insulation, effectively resealing it completely (just as your goo does)…only a bit neater.
If you must make a permanent connection with very good reliability (only second to the soldered connection) to a wire with no access to its terminations (the preferred place for adding a connection!), and also no ability to solder, cut wire, strip both ends, add new stripped wire, crimp into butt-crimp (suitable for gauge of double wire) after dipping twisted strands into ACZP (see:  http://www.sw-em.com/anti_corrosive_paste.htm ).  Additional protection by heat shrink is optional. " 


Shown below, from:  http://www.powerboxer.de/elektrik/66-stromklau  ...a BMW motorcycle enthusiast site, a graphic of why NOT to use these little electrical land-mines-in-waiting.  Their function is based on first cutting through the insulation, then into the stranded conductor (YIKES!  Cutting into or simply nicking  the conductor is one of the first BIG NO-NOs anybody having anything to do with electricity learns about...and that in a vibration environment!!  No thank you!).  Graphic is in German, and he calls it Stromklau - a variation on "Electrical Thief", but even non-German speakers will get a lot from the graphics showing how critical dimensions of the wire are for these to work at all... 

Conductors are shown as a solid orange (1) and this is not really correct...this is oversimplified...a solid conductor would not be able to flatten its shape as shown (2, 3) for this connection strategy to work at all.  Conductor should be shown as multi-stranded type (added better and more detailed graphic below!), so that as it is forced into the connection slot, slot splays open a bit under the force, strands also rearrange a bit into the available reduced space, and those conductors contacted by the sharp edges as the conductor is pressed into place are actually cut and weakened.  Add some vibration, and you can guess the inevitable outcome!

Scotchloks are available for different wire gauges, but 4, 5, 6 below show how conductor OD is critical to allow this concept to work at all...at 4, conductor OD is too big to force into the available slot (it would result in some combination of splaying the contact slot open, as well as cutting the conductor...a mechanical mess with unpredictable electrical function!), at 5, conductor is marginally too small resulting in a contact with low cross-sectional area (poor current handling capability!), and possibly intermittency, finally at 6, conductor is much too small resulting in not fully cutting through insulation in the first place.  With that many possible ways to fail, both short and long-term, the reader can see why I hate them...

 Source:  http://www.powerboxer.de/elektrik/66-stromklau   My mark-ups.

Here is a more detailed diagram of what happens when using Insulation Displacement Connectors...you get the cut conductor strands for free immediately, and Lord knows what in the future! 

IDCs are for weenies who don't know how to solder or make a proper crimp connection...and who don't care about long-term reliability of their own work.  They should never, ever, ever be used in a vibration environment like a car or even worse:  motorcycle!...you have been warned!! 

Link to Soldering Notes:  http://www.sw-em.com/Wiring%20Notes.htm#Soldering_Notes
Link to Crimping Notes:  http://www.sw-em.com/Wiring%20Notes.htm#Crimp_terminals_Tools_and_making_a_Proper_Crimp

The above information reoccurs at this Link, along with other notes.  See:  Wiring Notes and Related Information


Addition Information: 

Knob of SWF Switch disassembled. 

In the Lighted knob of the SWF Switch is a replaceable incandescent Bulb!  If the Bulb is not working first thing to check is if the switch housing is is making a good contact to the metal Dashboard, as this is the current return path for the lamp (ONLY, rest of the E-Flasher function would still work fine if this connection was poor or open!). 

To check a nonfunctioning E-Flasher Sw Indicator, turn ON the Flashers by pulling control knob...if indicator does not flash along with the audible clicks of the Flasher Element, push the Switch lightly to the side to possibly reestablish a poor Dashboard connection...if this causes the indicator to function as expected, the Bulb is not the problem!...simply unscrew Knob and tighten the Bushing Nut securing Switch assembly to Dashboard, replace Knob, and recheck. 

If manipulating switch grounding while E-Flasher is clicking away still brings no function, Bulb can be suspected...  Unscrew Knob, and carefully check for Bulb Resistance across the two connections at the base (it should be about 120Ohms)...if none is measured, carefully flex the black rubber knob in order to allow removal of Red Lens...then securing spring.  Bulb can then simply be pulled from its socket and tested on its own, and replaced as necessary.

Disassembled E-Flasher Switch Knob showing a partially internally plated bulb...
bulb may actually still function and light, but a badly blackened glass envelope will
clearly decrease light output...then, it just might be a good time to replace the bulb. 

Bulb Info: 

Volvo PN 277747, 942327 und 989800 (these bulbs are used in numerous places and models, therefore multiple PNs).

Bulb glass wedge base lamp 12 V 1,2 W
Socket version: W2x4,6d


Practical Experience Adding Emergency Flashers 122:  [Note:  These notes are not yet complete!]

If the addition of E-Flashers is accompanied by changing over to LEDs...it gets a bit more involved and complicated...first, an LED suitable Blinker Element must be installed, second, the Dashboard Indicator must be specifically considered for the type of vehicle and type (number of terminals) of Blinker Relay. 

122 - Diode Modification Necessary See above: https://www.sw-em.com/emergflash.htm#Directional_Indicator_ORing_Diode_Modification  ...also under OR-in Circuit Notes tech Article: Single Lamp Directional Indicator

1800 - No Diode Mod necessary IF a three terminal Blinker Element is in place.

444/544/210 - TBD [I believe circuit is similar to the 122, but I need to study and verify this!] 

Direct replacement for Bimetal 3 Terminal Blinker Element used in the E-Flasher Switch.

From Thread:  https://www.facebook.com/527003992/videos/10159048976633993/ ...this is Flasher unit "Constant Busch" on Faceplant was able to locate in England, for direct replacement in the Emergency Flasher Switch, where he noted "...terminals correspond directly...".  His source:  https://www.electricalcarservices.com/Product.aspx?ProductID=2956&strReferer=search&PPGR=0&fbclid=IwAR2DGeuKJV7Y6PowvdrxPH4-dIOm8qkJYqoNQAkiYGvscHWaFIpSO7OReUo
See YT video he posted about this conversion and adding an Emergency Flasher Switch:  https://youtu.be/U_Gn8R0XEsE


Details on Emergency Flasher Variation in late production 122:

As noted above, the '68 US DOT requirement to include an E-Flasher Switch was initially satisfied in that the stateside dealer would add such a switch before delivery to the customer, and typically below the dashboard (where it was well-located to potentially seriously injure the legs of a driver in the case of an accident...actually dangerous, and really unacceptable from a crash-safety point of view). 

After some point in '68, [PLACEHOLDER FOR CHASSIS NO] the factory began integrating the switch into the dashboard and harness...and the switch they used is the same SWF switch detailed above, and which the author prefers when retrofitting. 

With the last Amazon configuration produced by the factory, this is a somewhat unique installation where an SWF E-Flasher Sw was added to the dashboard, located above the Fan Switch. 

Owner Craig Weaver has an example of such a '68 122, and has kindly provided pix. 

Location of the SWF above the Fan Switch (removed here for service).  Evident is also the coveted late model Knee-Guard.  [...much nicer than an add-on, knee-killing E-Flasher switch located there!]  


While helping Craig with troubleshooting of non-working Directional Indicators, he observed that there was only the one Blinker Element (located in the typical spot, at the back of the SWF E-Flasher Switch).  This suggests and it was subsequently confirmed that the chassis was wired similar to the 140, where the one BE handled both normal Dir Ind, AND E-Flasher blinking duties, and this begs the question of just how these SWF switches were electrically incorporated.  [Certainly not as the author has shown above, when installed as an add-on!]

Working with Craig, I have further investigated the configuration, and can report that the electrical configuration is indeed similar to that of the follow-on 140 model.  The Three-Terminal BE plugged into the tail-end of the SWF Sw performs both blinking functions, just like in the 140s. 


Wiring of the SWF Switch behind the dashboard, is by way of wires added to, and present in the oe harness.  Evident is the single Blinker Element in its typical location on the back of the SWF switch.  Connected wire color-codes also look familiar and are consistent with the color codes of the earlier 122 chassis!


Here is a marked up Wiring Diagram of the configuration: 

Note the "other ends" of Blk (Ign Power), and Red (Batt Power) wires are not shown here, because they were found to enter, and disappear into the oe harness, and the actual location where they terminate could not easily be determined...their function however is clear! 

Mark-up of Wiring Diagram showing the manner in which factory incorporated the Emergency Flasher in the last Amazons produced (for the North American market?)




Consideration of the late 1800ES Emergency Flashers from the standpoint of the 4-Terminal Blinker/Flasher Element:  https://www.sw-em.com/Blinker_Relay_or_Element.htm#Four_Terminal_Blinker_Element_in_the_1800ES

See above: Directional Indicator ORing Diode Modification

See this considered under the general category of ORing circuits:  Single Lamp Directional Indicator

Related link to video on changing to LED lamps:  https://www.youtube.com/watch?v=Z6Cuhs6dtZo


External material is attributed.  This article is Copyright © 1993-2024.  Ronald Kwas.  The terms Volvo, SWF, Nesan and Scotchlok are used for reference only.  I have no affiliation with these companies other than to try to keep their products working for me (except for the Scotchloks, which I wouldn't use even to start a bonfire! **), help other enthusiasts do the same, and also present my highly opinionated results of the use of various products and techniques here.  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, or worshipped, at the reader's discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles! 

** ...the reader might notice that the chinese, famous for cheapening up products and turning them into utterly useless shit, haven't even figured out how to cheapen these things up...that should tell you something...!) 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you don’t, you’re just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the odd metaphor and probably wise-a** comment. 


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