I get lots of questions about relay operation so I thought I would post up some info. I dont know if it is sticky worthy but it will be here if any one wants to search.
A relays operation is simple, Low amperage signal input and high amperage output. It is often used so the computer has the ability to turn on and off a device that has more amperage than the computer can handle.
Some examples are cooling fans, A/C clutch and fuel pump. There are also non computer controlled devices such as , the horn, and starter.
Operation is as follows.
pin 87 is the main feed which will more than likely be hot all the time unless it is running through the ignition switch , then it may be on at certain positions of the key.
Pin 87a, not commonly used but when it is needed it is powered when the command signal from 85 is not present. output of this total opposite of pin 30.
Pin 30 will be the load, or the component that is to be switched on and off.
Pin 86 will be connected to the ground
Pin 85 will be the pos + command on signal which will come from a control device such as a computer or low amperage source.
Pins 85 and 86 are sometimes switched around, in reference to their inputs. at times the computer output will be a negative command on, which then pin 86 will be a +12v source.
Relays are very useful components , they can be use build isolation circuits . Such circuits are used in alarm and remote start installation. Especially in situations where the output of the alarm is a positive and the component to be attached needs a negative to turn it on or off. Examples would be power door locks and dome light circuits.
01 cav w/01 3400 gam gt 4t45e
Here is some further info on them. Tey are all basically the same thing, a couple have pin 87a.
01 cav w/01 3400 gam gt 4t45e
Great post. There so simple but so complicated to some.
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Quote:
A relays operation is simple, Low amperage signal input and high amperage output. It is often used so the computer has the ability to turn on and off a device that has more amperage than the computer can handle.
Actually that's not accurate. What you are stating above is more the characteristic of a transformer, not a relay. By definition a relay is an automatic switch used to separate two circuits. Relays themselves can use low amperage circuits to switch high amperage ones on and off, or it can also be used (although not typically in the automotive world) to use high amperage circuits to switch low amperage ones on or off. There are also very few relays that are physically controlled by the computer, most of them are from cabin switches (wipers and headlights for example).
The best way to think of a relay is just a junction between two or more circuits of different potentials where one circuit is used to switch another circuit on or off (turning on one side of the relay doesn't necessarily always turn on the other side, most relays have Normally Open and Normally Closed contacts that when the relay is energized, they will either close or open the circuit).
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You must be bored, your the only one so far that thought that was what it meant.
No transformers on cars anyway. so whats the point.
You know I could go into transformers right now , but its not worth the time to explain.
The reason for what I said was to be very general, Ya cant go into coils, voltage, and amperage results when trying to explain a operation of a device. Its general info not an education.
01 cav w/01 3400 gam gt 4t45e
