Below are two of the relays in my 1973 BMW 3.0CSi. Changeover relays with diode: used for suppressing coil voltage spikes, 85 and 86 terminals become polarity sensitive; 86 must remain a positive designation if the diode tracks according to the diagram example below. It’s the reason nearly every ignition coil on a European car has the numbers “15” (power from ignition switch) and “1” (low voltage to distributor) on the two small terminals, and also why starter motors are labeled “15” and “30.” Perhaps it is most useful in describing, understanding, and troubleshooting relays since the function of a relay, the socket it sits in, and the wiring of that socket, can always be reduced to the DIN terminals. 0000021691 00000 n When the coil of the relay is at rest (not energized), the common terminal (30) and the normally closed terminal (87a) have continuity. Something you really need to be careful of is the difference between so-called “Type A” and “Type B” relays. continuity. 87 and/or 87a will be connected to your controlled accessories that you wish to turn on and off with your relay. a relay provides no protection from overload or short-circuits. on some cars, this can burn out the igni-tion coil. All DIN relays should have the terminal numbers on the bottom. Check out my NEWEST 5-Pin Relay video here: https://www.youtube.com/watch?v=W2Mr2Zgv1Ck This is a how-to for wiring Bosch-style Automotive relays. Terminal 87 is linked to pin number 87b, giving double outputs from the single NO contact. 30, 87 - Normally open (N/O). They’re called DIN-standard relay terminal numbers; DIN stands for Deutsches Institut für Normung (German Institute for Standards). SPDT Relay : (Single Pole Double Throw Relay) an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one normally open terminal (87). You can swap them the other way, however—a relay with a resistor or a quenching diode can generally take the place of one without them. 0000010756 00000 n This is the most common type of relay. 0000003118 00000 n 0000008072 00000 n The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof.. When the relay is at rest 87a is connected to 30, and when the relay is energised 87 becomes connected to 30 (but never both at the same time). The most common electromechanical switch is a simple wall switch used to control the lights i n your ... style of relay. Numbers of a Relay 85 and 86 are the coil pins while 30, 87, and 87a are the switch pins. trailer <<963E8F1A88EA45369BD4162173F235A3>]/Prev 145210>> startxref 0 %%EOF 48 0 obj <>stream In it, the switch inside the relay has not just one position, but two—current can flow to one of two terminals at a time. Well maybe the above relay is for your headlights. h�b``�b``�````�ˀ The SPDT relay is one of the most useful configurations due to its flexibility-it can be used as a switching device, to isolate circuits, to interrupt circuits and to interrupt and switch at the same time. simply leave pin 87a disconnected. Here is a circuit diagram of a SPDT relay with a shorting diode. Look for relay diagrams or a relay schematic that is printed on the side of the relay to determine it's function. That’s still the plan, although you’re about to learn a bit of German. Other than the new ones usually being in a plastic case instead of a metal one, they haven’t really changed. Why are five listed? Basic 4 Pin Mini Relay ISO relays are currently used by … When you turn your headlights on you send voltage to pin 30 which when the relay is not active sends it right out to pin 87a, which happens to be your low-beams. H�tT�n�0}7��cŒt�����:���Z˳���Q�8醵P$�rtH��!6�Q/����1�T`$I -``�6X�A��ٳ���u�m@H�$�X��q��U���$͠��g$��qT�Y��y �w[�~�D��),Ө�Y�1����1L�h��m��� )�˸���0�,���J͓�Ũ�^j~`�� z�'Nw݇����~�����H�zX3e�����EK\�1ܙ��0"g t Rd��\7-S��N!�I!��'`�5z� ��#�*1�[����n��1nbߏr����f,��eЏC/� If the coil is not activated, 30 will always be connected to 87a. 0000021097 00000 n The resistance should be 75 ohms 5 ohms. Here is the DIN standard numbering of the four terminals on every relay: Output to device, normally open, pulled closed when coil is energized, Output to other device, normally closed, pulled open when coil is energized. I doubt you’ll find a car built since the 1980s with a relay that doesn’t follow the DIN standard. 0000022132 00000 n 0000138578 00000 n There’s also a less common kind called a Single Pole Double Pole (SPDT), or “changeover” relay. This way the middle 87b pin may be used as an extra power output. 4 0 obj <> endobj xref 4 45 0000000016 00000 n My relay has more than 5-leads/pins? Yes, the 87A is used for an extra throw on part of the switch side of the relay. While you can expect that any small square relay follows the DIN standard, my ’70s-era BMW 2002s have several weird-looking non-ice-cube relays that also follow the standard. 0000003165 00000 n OK, that’s not quite all there is, but it’s close. The relay is best thought of as two separate circuits: A low-current control circuit that supplies power to the electromagnet, and a high-current load circuit that is enabled when the switch contacts are pulled together and allows a lot of current to flow to a load device. 85 and 86 are the coil pins while 30, 87, and 87a are the switch pins. Numbers of a Relay. 20, 30 and 40 amp relays are common in automotive use. 0000007213 00000 n The numbers 85, 86, 30, 87 & 87a (or other numbers for different relay configurations) are normally moulded into the plastic next to each pin and also shown on the circuit schematic. How they The following simplified circuit diagram is often used to easily understand how a relay operates: The numbers 85, 86, 30, 87 & 87a (or other numbers for different relay. 0000076529 00000 n 0000123309 00000 n Q. 0000001522 00000 n If the coil is not activated, 30 will always be connected to 87a. Connecting Additional Devices to the Remote Turn On Wire. 0000051581 00000 n Unless it’s an emergency, I don’t recommend replacing one of these with a generic DIN relay without the suppression hardware, as it’s there for a reason. 0000052066 00000 n For this reason, you need to be very careful rummaging through the spare parts box to find a relay if one of yours has died, or accepting one from a well-meaning passer-by. It has a #30 pin (common) with two #87 pins (Normally Open) that are connected internally. On mine, you can see the labels for terminal 87 at the top and 30 on the left. You can think of this as the switch in OFF. Relay with double output . 0000001196 00000 n Since the late 1970s, nearly all of the relays that follow the DIN standard have a very uniform look—they’re little 1-inch cubes. Since terminal 85 is connected to ground, this causes current to flow through the coil in the electromagnet, which pulls the two internal switch contacts (30 and 87) together. We can now describe the relay circuit in the figure above using the DIN terminal numbers: Every DIN relay works this way. This is overwhelmingly the most common kind of relay found in a car. -Relay used to make isolation in two different circuits with different properties .-Relays are switches that open and close circuits electromechanically or electronically. Q. which pin would generally be common contact, open contact, and close contact - by Kory (vancouver, wa) A. I bought a 5-pin relay, can I still use it as a simple on/off(4pin) switch instead of a changeover switch? I see no reason to use a relay in this case. 3 - PIN 4 - PIN 5 - PIN ISO STANDARDIZED RELAYS ISO relays were designed to try and standardize relay connections, making it easier to test and design systems. 0000022575 00000 n Those few twists notwithstanding, to say it again, if you understand that powering terminal 86 and grounding terminal 85 energizes the coil, which then pulls the switch contacts together, connecting 30 (power) to 87 (the device), you know what you need to know. Pin 87a is usually not used when supplying +12V to a load, and the terminal is left open, or unconnected. YES. 0000077309 00000 n His new book, Ran When Parked: How I Road-Tripped a Decade-Dead BMW 2002tii a Thousand Miles Back Home, and How You Can, Too, is available here on Amazon. 0000021666 00000 n When the relay is energized, 87 and 87a change places—87 is disconnected from 30, and 87a is connected to 30. In any circuit with a DIN relay, without looking at a wiring diagram, you know that: Terminal 86 supplies power to the relay’s internal electromagnet. So how could we use this? 0000105260 00000 n 0000002603 00000 n 0000002031 00000 n The D series ice cube general purpose relays provide excellent functionality and are ideal for any application from controlling smaller loads, to those requiring high current-carrying capacity. Both are available from Bentley Publishers and Amazon. In the photo below, I’ve removed one of the relays from its socket and turned it over. First, let’s review. 0000010657 00000 n %PDF-1.4 %���� 87 and 87a are the two contacts to which 30 will connect. The most simple form of relay. That electromagnet (a little coil of wire wrapped around an iron core) then pulls two internal switch contacts together that allow a much larger amount of current to flow. 0000051321 00000 n The operating voltage of a relay is generally in DC.Small signal relays and low voltage power relays are usually in DC, but mains control relays and contactors quite frequently have AC coils.The rest of the terminals of a relay are used to connect either a AC(generally 50/60Hz) or DC circuit. of current to the load. 85 and 86 are the coil pins while 30, 87, and 87a are the contact pins. On the relay on the right, you can see the little schematic drawn on the side of it, which looks remarkably like my hand-drawn diagram showing the coil of the electromagnet with terminals 86 and 85, and the switch with terminals 30 and 87. 0000005587 00000 n These automotive relays have the standard five pins and can be wired to be Normally Open (N.O.) Since the motor is grounded, this causes the motor to turn on. 0000009478 00000 n Looking at the diagram below, you can see the pinout of a typical 12V relay. A wide array of coil voltages and contact configurations ensure there is a D series relay … use the carputer with the engine off. More importantly, relays are used in virtually every type of electronic device to swit ch voltages and electronic signals. Connect the ohmmeter between terminals 30 and 87A. 0000101078 00000 n I bought a 5-pin relay, can I still use it as a simple on/off switch instead of a changeover switch?-yes. When the relay is energized (ON), pins 3 and 5 have continuity. Normally closed (87a) indicates when the relay is NOT energized (on), this pin IS connected to the common terminal or a closed circuit. Or you can order personally inscribed copies through Rob’s website: www.robsiegel.com. Not all cars follow the DIN relay numbering standard—vintage British and American cars certainly don’t—but the standard was eventually adopted by virtually all automotive manufacturers. Favorite Answer. Surprisingly, although the numbering of DIN relays is standardized, the terminal locations on DIN relays are not completely standardized. Terminal 30 is connected to the battery. When the electromagnet isn’t energized, terminal 87 is normally open as it is in an SPST relay, but a second terminal, 87a, is attached to … Looking at the diagram, we see the pinout of a typical 12V relay. The relay coil is what is activated to perform the “switching” action. When the relay coil is energized, pins 87 and 30 will be connected. 0000086327 00000 n ������ ��30H2�3�`���Bn�6�i��5�g$Wh~t��� �>�1�1�e)g���)@��:��>�&��f��"���!�����lr�2�%& Y�d�H3�� V`� endstream endobj 5 0 obj <>>> endobj 6 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text/ImageC/ImageI]/Properties<>/XObject<>>>/Rotate 0/TrimBox[0.0 0.0 612.0 792.0]/Type/Page>> endobj 7 0 obj <> endobj 8 0 obj <> endobj 9 0 obj <> endobj 10 0 obj [/Indexed/DeviceCMYK 1 21 0 R] endobj 11 0 obj [/Indexed/DeviceCMYK 250 22 0 R] endobj 12 0 obj <>stream Single Pole, Double Throw (SPDT): If you have a relay with an 87a pin in the middle spot, it is a SPDT relay, sometimes called a "changeover relay." ����+�l��W���B����E�µ�U�ʼ���ԟ?��|�e�������bk���pz�g0�謏ߍ��U���͝��. The kind of relay I’ve described above, with the four DIN connections, is a Single Pole Single Throw (SPST) relay. Note that each pin is numbered. A relay is an electrically operated switch.It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. Note that each pin is numbered. 0000086290 00000 n Micro relays are more compact than the standard size and are an ideal choice when you need to save space - for example in an ATM fuse box set up with mini fuses. if your relay has more than 5-leads/pins then it is most likely a DPDT, MPDT, or Don’t call up a parts supplier and say, “I need a Type A DIN relay.” The take-away message is that you need to inspect and compare the pinouts of the old and new relays. (Don’t worry.). 87 and 87a are the two contacts to which 30 will connect. In it, the switch inside the relay has not just one position, but two—current can flow to one of two terminals at a time. The coil is located between pins 85 and 86. This type of relay allows you to wire two systems (such as a pair of lights) to activate at the same time. This term means that the single armature terminal (or pole, pin30) can be connected (or thrown) to two other terminals, pins 87a and 87. Sometime around the middle of the last century, German cars began following DIN 72552, which is a numbering standard for automotive electrical terminals. Rob Siegel has been writing the column The Hack Mechanic™ for BMW CCA Roundel Magazine for 30 years. I'd simply use a switch, as long as the switch is capable of handling 1 amp of current. It simply connects 30 (power) to 87 (the device). & N.C.) using pin 30 & both pins 87 & 87a. NO! 0000007909 00000 n Terminal 85 grounds the […] Sign up for the latest automotive news and videos—in short, everything for people who love cars, Last week, we talked about the relay, and we did our best to keep it simple. You can imagine a SPDT relay being used to switch between low beams and high beams (in fact, it’s a little more complicated than that, since there’s the flasher circuit, but conceptually it’s still a decent example). 87 and 87a are the two contacts to which 30 will connect. Last week we talked about the standard DIN numbers used on relays and the incredible utility they represent. Last week we offered a simple example using a relay that turns on an electric motor. using pins 30 & 87, Normally Closed (N.C.) using pins 30 & 87a, or wired as a Change Over (both N.O. Do I need to use a fuse if I use a relay? One of these will be used to ground your current, while the other will be connected to a switched power source. That’s the fifth row in the above table. Normally open (87) indicates when the relay is NOT energized (on); this pin is NOT connected to the common terminal (30) or an open circuit. 0000010475 00000 n Note that there are only a handful of online references to “Type A” and “Type B” relays. How to Wire Automotive SPDT Relays. 86 85 87a 30 87 Black Lead Red Lead 3D View Bottom View Schematic View 86 85 87 30 87a. What are those numbers? That’s all it is. With the relay removed from the vehicle, use an ohmmeter to check the resistance between terminals 85 and 86. Before we discuss troubleshooting relay-related wiring, let’s review. I found an SPDT relay in my 1972 BMW 2002tii in an unexpected place: the air conditioning. Normally open or normally closed types. 30, 87A - Normally closed (N/C). Below are some examples of basic 12 volt DC car relays. Live it. If the coil is not activated, 30 will always be connected to 87a. The general kind of a relay makes use of electromagnet so as to perform opening and closing of contacts, whereas in the other types of approaches like in the solid-state type of relays they use semiconductor properties for controlling purposes without depending on the movable components. 0000076764 00000 n In a changeover relay, the 87a What is a 50 51 relay? The following diagrams show the other types of commonly used automotive relays: Whenever installing a relay,use a quenching I believe generally it will switch the power from 86 to either 87or87A. 0000004860 00000 n 0000003214 00000 n They’re often called DIN relays, or ice cube relays, or Bosch relays, as many of them were originally made by Bosch. ... Pins 30 and 87a will be connected. This type of relay will work for this application also, but you will not use pin 87a. you must still fuse your power wires! You can’t tell, but that’s 85 on the right, and 86 on the bottom. It energizes the electromagnet, which connects 30 to 87 and powers the device. Learn it. 0000008707 00000 n Output for a Relay Realizing that 85 and 86 are the coil pins, these pins will be transferring the current through their coil. 0000002165 00000 n Terminals 87, 85, and, on a changeover relay, 87a, are I believe always in the same place, but terminals 30 and 86 can switch places with each other. It is reproduced below—this time with numbers on it. Two circuits (terminals 87 and 87a ) have a common terminal (30). Next week, we’ll talk about troubleshooting relays and relay circuitry, and the all-important trick of bypassing a relay by jumpering across socket terminals 30 and 87. The newer the car, the more variants you’re likely to find. A micro relay is a smaller version of the more popular standard relay and are used when space is at a premium. Humor me for a moment; I’ll get to that in a moment. YES! 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To turn on wire ) to activate at the diagram below, you can ’ t follow the numbers. State of the more popular standard relay and the Hack Mechanic™ Guide to automotive... Amp SPDT relay, can i still use it as a 'Mini '! A standard relay is a smaller version of the relays from its socket and it. Terminal is left open, or unconnected 5 have continuity in a plastic case instead of typical... Switch in OFF the diagram below, i ’ ve removed one of the switch thrown... Stands for Deutsches Institut für Normung ( German Institute for Standards ) a 5-pin,! While 30, 87 and 87a are the two contacts to which 30 will.! S website: www.robsiegel.com to wire two systems ( such as a 'Mini relay..