Blinker Relay (or Element or even Repeater Motor*) Notes
12/15 - R. Kwas  Revisions, on-going [Comments added]

Two Terminal Blinker Element in the 122
Three Terminal Blinker Element in the Carbureted 1800

Three Terminal Blinker Element in the Fuel Injected 1800
Four Terminal Blinker Element in the 1800ES
12V 544 Blinker Circuits


Background:  Blinker Elements are used to supply the intermittent blinking function to indicating circuits like the Directional Indicators and Emergency Flashers.  If the Directional Indicators stop working, it can be for a number of reasons (lamp failure, open fuse, or open circuit connections), but once normal troubleshooting points to the Blinker Element (see:  Electrical Troubleshooting Notes, Troubleshooting Directional Signals ), it should be noted that minor but significant differences exist between circuit of 122 and 1800 vehicles.  The 122 (and 12V 544s), use Two Terminal Elements, early 1800 use Three Terminal Elements, and  injected 1800s and 140s use Three or Four Terminal Elements.

In a circuit using a Two Terminal Element, the Blinker Control Lamp is connected across the two Directional Indicating circuits and is powered a bit uniquely.  The one side receives voltage from the powered Directional circuit, and the other side is not directly connected to chassis, but indirectly connected to chassis by way of the (unpowered) other Directional Indicator side circuit (while these lamps are not powered and OFF, they represent a low resistance to chassis, perfectly adequate for the return current connection for a 2W indicator lamp).  This is a cost-saving measure allowing an indication with just one Control Lamp on the dashboard, and this was more common for the European Automakers.  American Automakers typically had separate Control Lamps for each side.  These were simply an additional low wattage lamp supplied by each side's circuit.  I guess in Europe, they figured a reminder Indicator not specifying the side was enough, where in the US, they had an Indicator for each side...      

In circuits using Three Terminal Elements, a separate terminal from the Bylinker element powers the (single) Control lamp on the dashboard to remind driver that a Blinker is on.      

The Four Terminal variation adds a Chassis (31) connection which suggests their internals are using electronics (which couldn't function without a negative return current path...but these electronics also allow current monitoring to detect a bulb-out condition!).  

Technology of Blinker Elements:  Thermal (Bimetallic) Element vs. Electronic.  Elements of long ago employed a bimetallic element which was heated by the current going out to the Indicator lamps.  As the element heated, the heat cause the element to bend, opening a contact to the Load, depowering it and allowing bimetallic element to cool.  Cooling remade the contact and reestablished Load current, repeating the cycle. This is similar to the strategy and technology used  for the "Voltage Stabilizers" of the late 1800 and 140 from about '69 on.  Link:  Voltage Stabilizer  

Link to Additional Information:  Thermal Blinker Element

It stands to reason that since heating of the bimetallic element is a function of the Load Current, these elements are not suitable for use with LED replacements.  This is why when changing to LED lamps, Blinker Element must be also changed to a modern one using electronics to generate the cyclic blinking.  (See Additional InformationThermal Blinker Element not Suitable for LEDs)

It has also been observed that if a Blinker is a bimetal type, the dashboard Indicator blinks along with the corner Directional Indicators.  With electronic Blinker Elements, the dashboard Indicator blinks alternate to the actual Indicators of the vehicle (manufacturer dependent of course).  Timing of electronically controlled Blinker Elements is also less dependent on Load current...except for the type that have a load current sensing feature.  These blink at a faster rate when the load current drops from two lamps to one lamp, giving driver a lamp out indication in this manner. 

Blink Frequency Changes to Indicate Bulb Out:  The electronic Blinker Elements monitor the typical Load current and if this decreases (usually, but not always caused by a bulb out condition), these increase the blink frequency.  This is intended to alert driver to the condition.  When a bulb out condition occurs with the older Thermal Elements, sometime they don't cycle at all (recall the heating element requires Load current to function).  Also, a Blinker Element has no way of differentiating between decreased current cause by a bulb out or changing to LED.

On Thermal Elements, current will not flow to operate the heater element without the proper load connected to the output terminal...again this can be explained by the decrease in circuit Current.  

So one can see, there are many variations, depending on technology of element or manufacturer.  When replacing a Blinker element, one should ask for one with the same number of terminals, preferably terminal letter designation, and specify if lamps are incandescent or LED replacements.  ...and with so many variations, the final test is to simply check function in the vehicle.   


Two Terminal Blinker Element in the 122 and earlier Models:  The 122 uses a two terminal (thermal) Blinker Element typically located in a clip secured by one of the screws which also mounts the Choke mechanism bracket under the dashboard.   (Reference excerpt of 122 Wiring Diagram below. )  Electrically, it is series with Ignition Power provided by the Fuse 1 circuit and routes this to the Traffic (Directional) Indicator Switch.  Driver can then select to indicate Right or Left.

[Comment: ...or to leave them OFF while maneuvering in traffic, making me and other drivers wonder what other unpredictable actions might be coming up...or after having engaged the Directional Indicators, drivers can also leave them on continuously, completely oblivious to the never-ending clicking noise and blinking Dashboard Indicator in front of them, causing me and other drivers to wonder if they're taking the "right way around the earth"...and proving that "it takes all kinds".]  Remember:

Dashboard Indicator of the 122 circuit is wired across the two (left and Right) circuits in somewhat of a clever way...  If, for instance, Right Indicators are selected by driver, side of Indicator connected to the Left circuit effectively completes the current path to chassis through the low (OFF) resistance of the Left directional lamps.  

Two terminal Blinker Element and associated circuit, extract of 122 Wiring Diagram. 

In the 122 Wiring Diagram, Blinker Element terminals are not really labeled with standard numbers or nomenclature, because at the time, standardization of DIN 72552 was in its infancy.  However, the element is supplied by the load terminal of Fuse 1 (Fused Ignition Power), by way of a daisy-chain of wiring which supplies some of the other loads on that circuit...and 49a is shown as the label of the power terminal on the Directional Indicator Switch. 

See also Reference information:  Roffe and Bjorn test Directional Indicators


Three Terminal Blinker Element in the Carbureted 1800:  In the 1800, a three terminal Blinker Element is used.  It is powered by Ignition Power from the Fuse 1 circuit.  This type of element has a third terminal (P for Panel, in the British nomenclature), which supplies power to the Panel (Dashboard) Indicator.  The observant reader will notice this Dashboard Indicator implementation as different from the 122 circuit, because of that third terminal. 

Three terminal Blinker Element and associated circuit extract of (early) 1800 Wiring Diagram. 


Three Terminal Blinker Element in the Fuel Injected 1800:  In the injected 1800s a three terminal version was used, located on the back of the Emergency Flasher Switch similar to the 140s. 

Three terminal Blinker Element and associated circuit extract of (early) 1800E Wiring Diagram.

SWF Emergency Flasher Switch business-end, with associated 3-terminal Flasher Element.

Terminal designations on SWF Emergency Flasher Switch:

Switch (CW)  :  49a,   C (31),   49/30 
Flasher (CCW):   L,      P,           X

...this should make it clear, which Flasher terminal is associated with which switch terminal. 

Links to Deutsche Industie Norm (DIN) specification (DIN 72552), which standardizes the numbered terminal designations:
Extract from the spec.     
Complete listing (German).


This section has been rewritten, as new info (including correction details) has recently been learned in the course of troubleshooting a non-functioning Directional Indicator System on a '73 1800ES.  [Jun 2022]

Four Terminal Blinker Element in the 1800ES:  In the 1800ES, a four terminal version (with a separate chassis connection node) is shown on the factory Wiring Diagrams.  The separate chassis connection is necessary, because by the time the ES model came on-line, the technology of the Blinker Element had was no longer the simple, current operated, bi-metallic style, but it was now a fully electronic circuit, with bulb-out (current magnitude) sensing.  The BE is also no longer plugged into the back of the Emergency Flasher Switch, but secured to the Dashboard separately from the push-to-activate Round Switch shown here. 

1800ES dashboard showing late rocker switches, and push-to-activate Emergency Flasher Switch.

Push-to-activate Emergency Flasher Switch, rear view.


Four terminal Blinker Element and associated circuit extract of ('72) 1800ES Wiring Diagram.  Fourth wire (Highlighted Orange) is the chassis
(Grey Wire) connection, which is not present (or necessary) in earlier three terminal units, plugged into the back of SWF style Emergency Flasher Switch.
  Note also that Emergency Flasher Switch is shown in the OFF position, with the ON position being indicated by arrow (up, counter to what is shown
on other Wiring Diagrams, because it is now the push-to-activate Emergency Flasher Switch.


Terminal view of Four Terminal Blinker Element HELLA PN:  TBB26  4DB, 002479-07
Jim Perry picture used with his kind permission. 


Three Pin Bimetallic Blinker Element:  


Note British nomenclature as in the 1800 Wiring Diagram: B - Battery (well, not really...actually Ignition Power by way of Fuse 1, but who's counting...), L - Load, and P - Panel Indicator (Control Lamp or in this graphic: Test Lamp)


From our VW restoring friends at:

German nomenclature in this case:  15 - Ignition power, S54 - Load, and K (for Kontrolle - Dashboard Indicator)  ...and they printed the entire blinker circuit wiring  on the side of the Blinker Element...very handy!

Electronic Blinker Element:  

Good (external) Explanation of "Three Terminal Flasher Internal Circuitry" here:


Additional Information:  (Blinker Elements and LEDs)

Thermal Blinker Element not suitable for LEDs: 

[Excerpt from an e-mail]  "Thermal Blinker Element" simply means that the blinker element is an older style, which works on the basis of when lamps are ON, a bimetallic element within the Blinker Element is heated, causing it to bend, opening a contact, breaking the circuit (lamps go OFF), no current flowing allows the thermal element to cool back down, and bend back to starting position remaking contact, restarting cycle... and this whole principle is a function of the current going to the lamps. 

Naturally since this lamp current is significantly decreased when changing to LEDs, it throws a wrench into the whole operating principle of the thermal element blinker element.  ...this is where people simply "add resistors" ...these are essentially dummy loads which are added to the circuit in parallel to the lamps, to increase the lamp circuit current, and bring it back up to a high level which will allow the blinker element to work as intended.  But this is a true waste, because it truly wastes that additional current, strictly turning it into heat so that the old blinker can still see the old (high) current level and function as it did when incandescents were installed.  A MUCH better solution is to change over the blinker element at the same time to an electronic one (which does not use the "thermal element" technology, but an electronic timer to give the cyclic blinking).  These are available (ask for an LED suitable or compatible type!) and this is a one-time expense.  There are two-pin types or three-pin types of blinkers, so it's best to bring a blinker element into a parts supplier, and ask for an equivalent electronic one, and match it up before leaving, then try it in service to see it it plays well in a particular vehicle. 


Links to Discussions on the Subject: 

It would seem that an open Fuse 1 on a 122 will result in symptoms of no Blinkers!  That makes sense...Blinkers are supplied by Fuse 1! 

Brickboard Thread:  Electrical Mystery:

VOC Thread:  No Indicators P1800 (featuring the term "Repeater Motor" - thanks Cliverally!):



Directional Indicator Switch Mechanism  


References Information: 

Many Blinker Element Variations:  There are many variations of Flasher relays and Nomenclatures out there.  Some are functionally equivalent although the terminal designations are quite different.  Here a sample from the VW specialists at:   The top four are really the only ones used in vintage Volvos, but the four terminal RFL5 shown below is shown on the factory Wiring Diagram for the 1800E and ES models (although I have yet to see a four terminal Blinker Element installed on a vintage Volvo)...even on the units plugged into back of Emergency Flasher Switch, I've only ever seen three terminal units (see Four Terminal Blinker Element above) makes the point of taking your Blinker Element into the parts store with you to have them "match it up", then trying it in the parking lot before leaving...


The 12V 544 Blinker Circuits are substantially the same as in the Amazon, using a two terminal bi-metallic, current operated Blinker Element.  They also use the single Directional Indicator which does NOT lend itself to being changed to an LED without further consideration (See:  Single Lamp Directional Indicator  ): 


Bimetallic Element:  Link to a popular reference source:

Here is a nice explanation of an Electronic 3 terminal Blinker:


Roffe and Bjorn test Directional Indicators:


Always check and keep your Blinker Fluid filled! 

Finally...  Please remember: 


External material sources are attributed.  Otherwise, this article is Copyright © 2001-2022  Ronald Kwas.   The term Volvo is used for reference only.  I have no affiliation with this company other than to try to keep its' fine vintage products working for me, help other enthusiasts do the same, and also present my highly opinionated results of that process here.  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles! 

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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