In an attempt to fix my starter switch problem I got a 2 pole single throw relay and asked for a pigtail also. Well he gave me a pigtail with 4 leads coming out of it. Thats fine as I don't need to use the center, normally closed, pin.
What I don't get is the extra jumpers on the pigtail. I am almost positive I don't want them here for my use. I am curious though. It seems to me that a jumper from 30 to 85 and another jumper with what appears to be some resistor or small fuse inline goes from 85 to 86 would defeat the whole purpose of the internal switching of the device.
What is the purpose of these? Is it application specific? What would you use this set up for? Came from a car stereo/alarm shop.
I will probably just cut off the little jumpers and use the pigtail's 4 wires.
I can put up a pic later if needed.

 

Likely a diode to help control the inductive current spike when you turn the relay off. Helps protect whatever is turning the relay on and off. And the 30-85 jumper is likely to allow easier connection of the relay, all you need to do is ground 86 to turn it on, power comes from 30 terminal (aka a switched ground configuration). But you need switched power setup for the starter, the solenoid gets 12 volt power to turn it on and it is grounded (via the starter being bolted to the engine block).

 

So I don't need to cut any of these jumpers? And in this configuration I'd use 85 as + and 86 for the ground instead of 86(+) and 85(-). It wouldn't work with 86 as + and 85 - with the jumpers set up this way, right? 30 would get power from 85 as well as direct, fused battery power which will not tax the old switch? Path of least resistance, I guess.
I am going to splice into the switch and starter wires instead of cutting the wires. This is because I still hear the C.O.R click when I hit the start posotion with the key and don't think I should cut that off.
Does this sound right?

 

Well, you want the ignition switch to turn the relay on, it supplies 12 volts and assumes the other end of that load is grounded (i.e. just like the starter solenoid). So you would NOT want to have 30 tied to 85, you want them independent, unless of course you want to wire things the way Toyota did:
- http://www.4crawler.com/4x4/CheapTri...l#OtherOptions


Problem with the way Toyota wired things is that all the power for the relay ends up flowing through the tired old ignition switch, so there is no gain by adding the relay (other than allowing the neutral start thing to work). Sp the way mine is, 85 from the solenoid wire, 86 to ground, 30 to the battery (fused or circuit breaker) and 87 to the solenoid terminal.

 

Can 85 and 86 have the +,- either way? So I do need to cut both of the jumpers so I have only the 4 main wires from the pigtail? The jumper from 85 to 86 with the diode(?) is okay or not? Seems harmless to me as power only gets there with the key.

 

Relays are non-polarized, just a coil of wire, current flows they magnetize and go click. They even work off of AC current. Problem is the diode, if you keep it, it probably has to be oriented the right way. Why? Diodes are uni-directional, current flows one way and not the other. It is there to short out and soak up any negative voltage spike as you cut power to the coil. If you reverse polarity on the diode, it will conduct all the time, as least until it pops.

 

I can read some writing on the diode and one end has a grey top similar to a duracel but grey.
l
XXXXXX this part is grey
lIN4005l
l TO l
l__.___l
l
Does this identify the currnet flow direction?

 

Yep:
- http://en.wikipedia.org/wiki/Diode

 

Okay I now see the direction of flow but is this being used in reverse bias mode? I want to learn but think I don't really need this diode. It didn't come with the relay just with the pigtail. I'm not sure but I think the direction of flow to this diode is the opposite from of the flow through the relay. The diode only works as the power is turned of or the key is released from the start position.
Am I close?

 

Simple step, lose the diode, it is not like your starter solenoid has any diode around it and it is a MUCH BIGGER coil/inductor than the little relay and makes a much bigger spark.

And yes, the diode is likely hooked up backwards. Why. Like I said before, to keep the voltage from going negative when you turn off the relay. Problem with an inductor, like a relay coil, is that when it has a magnetic field (i.e. it is turned on) and you kill the current, that field collapses and as Mr. Faraday was keen to point out, when an electrical conductor is inside a moving (collapsing) magnetic field, a voltage is induced. Since the field is shrinking, that voltage will go negative then slowly return to 0 volts. Problem is things like computers or tiny switches turning a relay on and off do not like to see big negative voltage spikes so you add the backwards diode to short out the relay coil when it is turned off. You can see this happen with the starter solenoid easier, if you energize it by hand then disconnect the wire, you'll likely see a good sized spark when you disconnect the wire, probably much bigger than the spark when you touched the wire to the solenoid terminal.