Bosch 5 pin 12v relay help

[Circuitrider]

I am installing a fuse box today and want to use a relay to keep all accessories that will eventually go into that box switched.

I have a Bosch 5 pin relay and I'm not sure what goes where. I know I have to use ground, hot from battery, but I'm not sure if I take a positive or negative from (e.g. horn) to be switched and what pin it goes to.

85 (???) What goes here? Switched wire? +, -, ?
86 ground out to fuse block
87a (???) What goes here?
87Hot in from battery
30Hot out to fuse block

Can you check this and help me make sure I do this right?

Thanks!
Matthew

 

[Motogiro]

I am installing a fuse box today and want to use a relay to keep all accessories that will eventually go into that box switched.

I have a Bosch 5 pin relay and I'm not sure what goes where. I know I have to use ground, hot from battery, but I'm not sure if I take a positive or negative from (e.g. horn) to be switched and what pin it goes to.

85 (???) What goes here? Switched wire? +, -, ?
86 ground out to fuse block
87a (???) What goes here?
87Hot in from battery
30Hot out to fuse block

Can you check this and help me make sure I do this right?
Thanks!
Matthew

Hey Mathew!
Check out this link: Relay Basics

Pins 85 and 86 will be the coil voltage. The coil operates the mechanical part of the relay that make the contact/s open and/or close. There are many different types of relay configurations which will vary with number of contacts, normally open or normally closed contact sets etc. Many different power handling configurations.

For your operation pin 85 will connect to red with white tracer wire on the relay at the top of your battery. Pin 86 on your relay will go to the negative/ground. If you get pin 85 and 86 reversed in this set up it won't matter because the coil doesn't care which polarity it's connected to. It will operated the relay.

Pin 87 will go to the positive battery terminal. You will want this wire to have an in-line fuse near the battery terminal.

Pin 30 will go to your new fuse panel positive lead.
Pin 87a will not be used in your set-up. There will be no voltage on pin 87a if you wire the relay as I've described so you can just leave it blank.

Have fun!

 

[FinalImpact]

In addition to ^^ above ^^

With a bikes battery, an ohm meter and some cheapie alligator clips you can verify relay operation pretty quickly but I'm guessing most are marked and Cliff's info should resolve any questions.

One thing about crimping; a 12 gauge wire should be able to withstand nearly 100 in/lbs of pull and not come apart. So, any basic tugging on a wire joint should not slip or fail completely.

Have fun!

 

[Circuitrider]

I already have the horn installed. I am just trying to find the "trigger" to make sure the key shuts off the new fuse box. So does the same setup work for the fusebox as the horn as listed above?

Thanks for the help!

 

[Motogiro]

I already have the horn installed. I am just trying to find the "trigger" to make sure the key shuts off the new fuse box. So does the same setup work for the fusebox as the horn as listed above?

Thanks for the help!

Sorry... I just edited the hookup for your relay box. See my post#2

 

[Circuitrider]

Sorry... I just edited the hookup for your relay box. See my post#2

No worries! Thanks for the help!

 

[Motogiro]

No worries! Thanks for the help!

Here's another schematic that might work....Lol!

 

[FinalImpact]

Any need to add a protection DIODE here Mr Cliff?
[MENTION=2579]Motogiro[/MENTION]

I mean, yes, the relay will work and function, but switching it off will generate high voltage which will be sent through the wiring harness.

 

[Motogiro]

Any need to add a protection DIODE here Mr Cliff?
[MENTION=2579]Motogiro[/MENTION]

I mean, yes, the relay will work and function, but switching it off will generate high voltage which will be sent through the wiring harness.

It never hurts to add a protection diode but most all inputs on sensitive modules today incorporate protection. Also once you add the protection the coils wiring will become polarity specific.