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Relay wiring

3K views 19 replies 9 participants last post by  dsd1983 
#1 ·
I bought a switch panel for my car off ebay.

It came with a relay and it is a 4 prong with 3 wires. I have not seen this before. It has 30&85 together on the relay.

This unit did not come with any instructions. So I am kind of not sure here.
I have googled this type of relay and checked summit and did not find anything.

Does anyone have insight on this?

Here is the link to the unit I bought
New 12V Ignition Switch Panel Engine Start Push Button LED Toggle for Racing Car | eBay

The relay wires are numbered like so
Blue=87
Red=30
Black=86

Thanks

Doug
 
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#4 ·
To answer your question.....

Terminal 30 is the common
Terminal 85 is one side of the relay coil
Terminal 86 is the other side of the relay coil
Terminal 87 is the Normally Open
Terminal 87a is the Normally Closed

So I assume with 30 and 85 bridged, when the Power switch is switched on, the relay is energized and connects 30 and 87.... which sends power out of 87. I also assume, 86 is the relay coil ground. Basically using the relay as a secondary switch to switch a higher amp draw component.
 
#5 ·
"Should be two wires for power these should be black and red" I have never seen a relay with a black "power" wire. As always it could be any color........ but I have only seen red, yellow or blue as + voltage wire colors and have only seen black as a ground.

HEI Dizzy's (at least what I'm used to) draw 4 amps running and may pull 20 during the start surge...... so your 20 amp should work fine (wouldn't recommend you running the dizzy thru a relay). GM starter solenoid about 3-4 amps....... it's the horn and headlights that need the higher amp relays

IMO the relay in the kit was intended to provide power to the three aux switches or provide a power out when you press the start switch. you could wire the switches anyway you wish, and as stated above bosh style relays are the way to go. Many vehicles use the bosh type, in various sizes and shapes, I like the Oman(spelling may not be correct) relays that come in Fords and Doges...... very small and compact.
 
#7 · (Edited)
To me, thats a non-thermostat controlled electric fan relay,whereas the fan is on whenever the ignition is on..or to a toggle switch...red to switched 12v--- blue to fan---black to ground.Could be used as a fuel pump relay,but the blue wire(color of most electric fan wiring) is telling me fan relay.The white crossover wire in your relay would eliminate where the thermostat option wires would normally be.
 
#8 ·
IMHO, stick with EOD Guy's overview, which best gives you the relay's projected operation. Most importantly, get a small motorcycle/scooter 12V battery, and use it to bench-test the relay to confirm its operation in its currently wired state, then you will confidently know for sure.

Also, I'm curious, what vehicle are you planning to wire this switch panel into? That might allow for us to give you a more detailed answer to the overall wiring of the panel, not just concentrating on the relay wiring......
 
#10 ·
a few things...

what are you installing it on..

what items are you powering..

you have the starter..

the ignition system

the instrument cluster.

is the alternator light in the instrument cluster controlling the alternator or do you have a true One wire alternator.

do you have wipers,

do you have a heater fan and ac compressor ?

do you have a radio.. or stereo system.

that is probably a 30 Amp 12 volt ISO relay..

you may want to study the lower right corner of this fairly large poster from bosch relays..

http://aa-boschap-sg.resource.bosch...ories__auto_parts/MKG3_Relaisposter_de_GZ.pdf

you will also want to download this automotive relay wiring guide..

http://www.dlcparts.com/images/BoschGuide.pdf



you might want to look at those imported switches to see if the AMP rating is listed on the sides.

you will want to figure out what you want to power with the switches .. and what you want to power with relays...

Relays reduce the LOAD going thru the switch contacts.. most relays take less than 1 amp to turn on by powering the coil..

if you are removing the stock ignition switch.. you may want to also install a BATTERY CUT OFF SWITCH... so your car will be safe to be around if anybody gets in a pushed the button.. going. .i wonder what this does..

i would imagine that the RELAY included will be activated by the covered swtich on the left and cut power to the PUSH button switch.. so there is no chance of the starter getting powered unless the ignition switch on the left side is UP and latched under the safety cover. makes it slightly safer to be around..

you can with a remote battery cut off switch.. either install just a push rod with a Knob like NHRA mandates.. or instead of or also.. install a PTO cable so you can turn the switch from the drivers seat remotely.

if you are wiring up a stock production wiring harness for a car or truck.. do you have a proper wiring diagram for that car.. so you know what you need..
 
#11 ·
I got it working
Thanks for all the insight



The red toggle is the relay power switch
Push Button for the starter
ACC 1 is for 7 gauges and electric cutouts
ACC 2 is for MSD Box 6AL
ACC 3 is for electric fuel pump

This is for my 69 charger

I left all the stock electrical in the car like it was
When I swapped in my 440 I put in switches
I just wanted to get a different looking panel and found this one
 
#12 ·
it kinda defeats the purpose of a relay when you power it from the switch??
usually you trigger the relay with the switch, and power it from the battery,,
to keep the load [amps] off the switch??
not sure what the plan is tho??

x2 check the amp rating on those switches..
 
#13 · (Edited)
JJLT1 - I am going to wire the relay to the battery like you are talking about.
And use the switch to trigger it.

The starter button has its own 15A circuit breaker and I plan to just wire it from the battery to the breaker and out to the solenoid.

All the toggle/flip switches on this panel are shown at 20A.

I am bench testing all this. I have a workbench with a battery, test light, wires etc.

Did the Charger a few years back and I just started working on it again

Thanks for the help everyone

Will post update, install pics

Here is a pic of the car
 

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#14 ·
there are some inportant things to know about external MSD boxes..

to make them live.. you need to hook the thick black wire to a good ground that is connected to the body but also the engine block/heads..

there are a few racers who have created 4 ring terminal harnesses for the ground..

one ring terminal for the back of one head.. one for the back of the other head.. one for the distributor housing if you are running a module inside the distributor.. and the last one to the firewall or where ever the MSD thick black wire is connected..

when the spark comes out of the coil.. it goes thru the wires and across the spark plugs. but it does not end there.. it has to make a complete circuit.. back to the module that is hooked to the coil.. that is the thick black wire..

guess what.. if you have the thick black wire hooked to the battery as the directions say.. all you spark return has to go up the negative battery cable to get to the long thick black cable to the msd box..

with a firewall or engine ground.. the spark return path is a LOT shorter.. and there is less chance to have the spark return try to get to the module ground via some other path..

please print and perform this test..

http://i.imgur.com/WMDprhm.jpg

test 5 is to the connector near the battery or to the threaded stud on the starter relay and you will expect 7/10ths of a volt with the engine running and the headlights on of voltage drop.. as the stock designed charging systems on Dodges go a LONG way..

with the additional current draw of the MSD box.. you may want to think about running an additional wire from the alternator output to the positive battery so you bypass the long long wiring thru the amp meter.. you can also remove one amp meter nut and move the free wire to the top of the other amp meter stud nut.. and install the extra nut on there. that bypasses the amp meter.. unless it shorts out.. and it should not with only power on one stud. the reason for the alternator to positive battery wire is to remove the multiple passes thru the bulk head connector also..

this is all up to YOU... please at least perform the voltage drop test i linked..

15 inch braided ground straps are available at most parts stores to hook the engine/head to the firewall in the help section.. 3/8 ring on one end.. 1/4 on the other end. .

this is important for the reason that the alternator puts out its electrons on the negative side. and almost 2 volts more than the battery can supply.. run the voltage drop test to prove its properly hooked up..

thank you for listening.

my brother in law had a 68 charger.. somehow he took it to el mirage.. bone stock 383 4barrel automatic car.. ran 156 MPH. the motor only lasted a few days after that.

decades ago i worked for a paint store with my dad.. they sent me on a rush delivery to the burbank studios.. dukes of hazard set.. i got there.. general lees parked all over the place. i made my delivery.. got the invoice signed.. just turned to leave to check out the generals and the crew in the sound stage parted at the big door.. 2 german shepherds on leash walked in followed by cathrine bach in full daisy duke costume. what little there was of it.. think she looked good on the TV.. you should have seen her in person. that image is burned in the back of my brain.. i completely forgot to look at the generals as i was leaving.
 
#15 ·
wayne

thanks for the response. I will do the test and the msd ground the way you are talking about.



I did get the relay wired up and I used the

the black wire for the ground
the red wire went to the 12v out on the toggle switch
so when the switch comes on the relay comes on
the blue wire is out power the rest of the panel


I will take some pics of the action and post later today or tomorrow
will keep updating

Thanks to all

Doug
 
#16 ·
Each of your switches can be used to throw a relay for higher amp draws etc.....

You might think about installing a 70 amp circuit breaker to feed you entire electrical system, that's how I have mine wired..... everything except the Batt-to-Starter cable is run thru a 70 amp CB. If something shorts BC pops shutting of the entire system..... no melt down. It also makes it nice when working on the electrical system, manually pop the CB and the system is dead and no smoke leaves the wires etc....... My car sits all winter, had to use a trickle charger in the past, this winter with out the trickle..... no issue with a flat battery.
 
#17 · (Edited)
You guys are spot on here with that 70A CB. I will change to that.
That is similar to the maxi fuse I used on a painless system I installed on my falcon a couple years ago.


Did not get anything done over the weekend. Took the wife out of town for a couple days.



I will work on it more this week and will update with some pics and stuff.

Thanks for all the help
 
#20 ·
got everything iinstalled

Used the relay that came with the switch panel to power of the three switches on the right side

the push button switch is wired up on its own to the starter

three switches on the right
one goes to MSD box
one to fuel pump relay
one to aftermarket gauge

the fuel pump relay and the relay for the switch panel installed under the dash next to the switch panel for easy access
 

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