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. Last week we offered a simple example using a relay that turns on an electric motor. Do I need to use a fuse if I use a relay? 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. Favorite Answer. 0000002165 00000 n Remove relay from connector before Testing. 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. Relay with dual contacts Well maybe the above relay is for your headlights. 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. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof.. 0000093859 00000 n An SPDT relay is connected to both the heater blower box and a/c, allowing one of them to be on at a time, but not both. I'd simply use a switch, as long as the switch is capable of handling 1 amp of current. The ohmmeter should show continuity between terminals 30 and 87A. It energizes the electromagnet, which connects 30 to 87 and powers the device. Both are available from Bentley Publishers and Amazon. simply leave pin 87a disconnected Does a relay take the place of a fuse? 0000086290 00000 n If the coil is not activated, 30 will always be connected to 87a. -Relay used to make isolation in two different circuits with different properties .-Relays are switches that open and close circuits electromechanically or electronically. ����+�l��W���B����E�µ�U�ʼ���ԟ?��|�e�������bk���pz�g0�謏ߍ��U���͝��. 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. 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. 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. 20, 30 and 40 amp relays are common in automotive use. 0000003118 00000 n 85 and 86 are the coil pins while 30, 87, and 87a are the contact pins. 0000010475 00000 n 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. 0000051581 00000 n 87 and 87a are the two contacts to which 30 will connect. 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. Other than the new ones usually being in a plastic case instead of a metal one, they haven’t really changed. These automotive relays have the standard five pins and can be wired to be Normally Open (N.O.) 0000004860 00000 n Basic 4 Pin Mini Relay This is overwhelmingly the most common kind of relay found in a car. Relays control one electrical circuit by opening and closing contacts in another circuit. Humor me for a moment; I’ll get to that in a moment. 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). closing 30 and 87.This type of relay is known as a single pole,double throw (SPDT). if your relay has more than 5-leads/pins then it is most likely a DPDT, MPDT, or OK, that’s not quite all there is, but it’s close. 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/� You can’t tell, but that’s 85 on the right, and 86 on the bottom. 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. using pins 30 & 87, Normally Closed (N.C.) using pins 30 & 87a, or wired as a Change Over (both N.O. 86 85 87a 30 87 Black Lead Red Lead 3D View Bottom View Schematic View 86 85 87 30 87a. 0000021345 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. 0000138578 00000 n Terminal 30 is connected to the battery. 0000022575 00000 n 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. h�b``�b``�````�ˀ 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. a relay provides no protection from overload or short-circuits. When the external switch is thrown, terminal 86 receives 12 volts. Sometime around the middle of the last century, German cars began following DIN 72552, which is a numbering standard for automotive electrical terminals. 0000076529 00000 n The coil is located between pins 85 and 86. 85 and 86 are the coil pins while 30, 87, and 87a are the switch pins. 87 and 87a are the two contacts to which 30 will connect. Live it. Yes, the 87A is used for an extra throw on part of the switch side of the relay. 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). Normally open or normally closed types. Connect the ohmmeter between terminals 30 and 87A. 0000009478 00000 n In the photo below, I’ve removed one of the relays from its socket and turned it over. A wide array of coil voltages and contact configurations ensure there is a D series 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. 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. This way the middle 87b pin may be used as an extra power output. 0000105260 00000 n When the relay is energized, 87 and 87a change places—87 is disconnected from 30, and 87a is connected to 30. (Don’t worry.). 0000022132 00000 n In a changeover relay, the 87a 0000001414 00000 n 0000021691 00000 n 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. My relay has more than 5-leads/pins? 0000090477 00000 n use the carputer with the engine off. Output for a Relay Realizing that 85 and 86 are the coil pins, these pins will be transferring the current through their coil. Something you really need to be careful of is the difference between so-called “Type A” and “Type B” relays. Note that there are only a handful of online references to “Type A” and “Type B” relays. 30 - Terminal 30 is common.One side of what-ever is being controlled goes here. Pin 87a is usually not used when supplying +12V to a load, and the terminal is left open, or unconnected. 0000007213 00000 n Two circuits (terminals 87 and 87a ) have a common terminal (30). trailer <<963E8F1A88EA45369BD4162173F235A3>]/Prev 145210>> startxref 0 %%EOF 48 0 obj <>stream The kind of relay I’ve described above, with the four DIN connections, is a Single Pole Single Throw (SPST) relay. Look for relay diagrams or a relay schematic that is printed on the side of the relay to determine it's function. The resistance should be 75 ohms 5 ohms. I see no reason to use a relay in this case. Looking at the diagram below, you can see the pinout of a typical 12V relay. Learn it. Normally closed (87a) indicates when the relay is NOT energized (on), this pin IS connected to the common terminal or a closed circuit. 0000002031 00000 n That’s the fifth row in the above table. Here is a circuit diagram of a SPDT relay with a shorting diode. Since the motor is grounded, this causes the motor to turn on. 0000006367 00000 n More importantly, relays are used in virtually every type of electronic device to swit ch voltages and electronic signals. 0000010588 00000 n I believe generally it will switch the power from 86 to either 87or87A. Below are two of the relays in my 1973 BMW 3.0CSi. 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. Rob Siegel has been writing the column The Hack Mechanic™ for BMW CCA Roundel Magazine for 30 years. 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. 0000003214 00000 n 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. 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. 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. 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. 0000001196 00000 n 0000010756 00000 n 0000123309 00000 n Let’s look at a square DIN relay and the socket it sits in. 0000001522 00000 n 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). Looking at the diagram, we see the pinout of a typical 12V relay. What is a 50 51 relay? I bought a 5-pin relay, can I still use it as a simple on/off(4pin) switch instead of a changeover switch? 0000010657 00000 n 0000052066 00000 n They’re called DIN-standard relay terminal numbers; DIN stands for Deutsches Institut für Normung (German Institute for Standards). continuity. 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. Note, a standard relay is also sometimes referred to as a 'Mini Relay'. I bought a 5-pin relay, can I still use it as a simple on/off switch instead of a changeover switch?-yes. Note that each pin is numbered. Terminal 85 grounds the […] 30, 87 - Normally open (N/O). NO! So when the electromagnet pulls the two internal switch contacts together, current flows from terminal 30 out terminal 87, which is connected to the device we want the relay to control, in our case an electric motor. This type of relay allows you to wire two systems (such as a pair of lights) to activate at the same time. 0000101078 00000 n ... Pins 30 and 87a will be connected. It simply connects 30 (power) to 87 (the device). 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. 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. 0000051321 00000 n The relay is a remote-controlled switch that works on the principle that a tiny amount of current can be used to energize a little internal electromagnet. 87 and/or 87a will be connected to your controlled accessories that you wish to turn on and off with your relay. The following diagrams show the other types of commonly used automotive relays: Whenever installing a relay,use a quenching When the relay is energized (ON), pins 3 and 5 have continuity. How to Wire Automotive SPDT Relays. 87 and 87a are the two contacts to which 30 will connect. of current to the load. That’s all it is. DIN 72552 covers far more than just relays. 0000003165 00000 n Q. Using a 30 amp SPDT relay, connect terminal #87 to. When the relay coil is energized, pins 87 and 30 will be connected. (ASD) Relay Testing With An Ohmmeter. First, let’s review. 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. Think of this as the relay in the Normally Closed (OFF) position. The most simple form of relay. 0000009422 00000 n It has a #30 pin (common) with two #87 pins (Normally Open) that are connected internally. & N.C.) using pin 30 & both pins 87 & 87a. 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. You can think of this as the switch in OFF. Or you can order personally inscribed copies through Rob’s website: www.robsiegel.com. you must still fuse your power wires! Last week we talked about the standard DIN numbers used on relays and the incredible utility they represent. %PDF-1.4 %���� 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. Sometimes the DIN numbers are also on the socket, but on this one they’re not. 4 0 obj <> endobj xref 4 45 0000000016 00000 n So how could we use this? I doubt you’ll find a car built since the 1980s with a relay that doesn’t follow the DIN standard. 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." 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. 0000005587 00000 n YES. In addition, he is the author of Memoirs of a Hack Mechanic and The Hack Mechanic™ Guide to European Automotive Electrical Systems. 0000086327 00000 n Surprisingly, although the numbering of DIN relays is standardized, the terminal locations on DIN relays are not completely standardized. If you have the relay “type” nailed down, within both SPST and SPDT relays there are a few variations with internal diodes and/or resistors for noise suppression. ISO relays are currently used by … I found an SPDT relay in my 1972 BMW 2002tii in an unexpected place: the air conditioning. 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). 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. ������ ��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 0000008072 00000 n Relay with double output . 0000004051 00000 n “Normally” refers to the state of the relay not being energized. The relay coil is what is activated to perform the “switching” action. It is reproduced below—this time with numbers on it. 0000076764 00000 n Why are five listed? This term means that the single armature terminal (or pole, pin30) can be connected (or thrown) to two other terminals, pins 87a and 87. 0000022831 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. Connecting Additional Devices to the Remote Turn On Wire. What are those numbers? This is the most common type of relay. 0000008707 00000 n We can now describe the relay circuit in the figure above using the DIN terminal numbers: Every DIN relay works this way. 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 the normally closed position of the internal switch. On mine, you can see the labels for terminal 87 at the top and 30 on the left. The most common electromechanical switch is a simple wall switch used to control the lights i n your ... style of relay. 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Terminal 87 is linked to pin number 87b, giving double outputs from the single NO contact. Numbers of a Relay. When the coil of the relay is at rest (not energized), the common terminal (30) and the normally closed terminal (87a) have continuity. Note that each pin is numbered. 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. YES! 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 … They’re often called DIN relays, or ice cube relays, or Bosch relays, as many of them were originally made by Bosch. That’s still the plan, although you’re about to learn a bit of German. 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. This type of relay will work for this application also, but you will not use pin 87a. 30, 87A - Normally closed (N/C). Numbers of a Relay 85 and 86 are the coil pins while 30, 87, and 87a are the switch pins. One of these will be used to ground your current, while the other will be connected to a switched power source. A micro relay is a smaller version of the more popular standard relay and are used when space is at a premium. 0000002603 00000 n There’s also a less common kind called a Single Pole Double Pole (SPDT), or “changeover” relay. Q. which pin would generally be common contact, open contact, and close contact - by Kory (vancouver, wa) A. 0000021666 00000 n 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. on some cars, this can burn out the igni-tion coil. The newer the car, the more variants you’re likely to find. All DIN relays should have the terminal numbers on the bottom. 0000021097 00000 n On/Off switch instead of a SPDT relay, can i still use it as a relay. Double Pole ( SPDT ), or combinations thereof i still use it as a single Pole double Pole SPDT. Relays control one electrical circuit by opening and closing contacts in another circuit energized... Called a single Pole double Pole ( SPDT ) 86 85 87a 30 87 Black Lead Red Lead View. 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