Relay wiring

Hello. I’m wiring up heated seats (aftermarket Mazda RX8 fitted by a PO). I’m using OE dash switches and am using relays. I have 2 questions that I keep going round in circles over.
1. Do I need a fuse between output pin 87 before accessory in addition to battery to pin 30 fuse?
2. Are OE switches switched negative or positive and does it make a difference if I switch into pin 86 with 85 ground, or round the other way?

Cheers.

Just a fuse to the feed (30) will be OK - I like the relays with the fuse built in ...
85 is relay ground.

Cheers @miktdish

110Matty said:

Hello. I’m wiring up heated seats (aftermarket Mazda RX8 fitted by a PO). I’m using OE dash switches and am using relays. I have 2 questions that I keep going round in circles over.
1. Do I need a fuse between output pin 87 before accessory in addition to battery to pin 30 fuse?
2. Are OE switches switched negative or positive and does it make a difference if I switch into pin 86 with 85 ground, or round the other way?

Cheers.

Click to expand...

What oem dash switches are you using, for what vehicle? From memory the td5 style switches are a switched earth so need wiring differently to a normal toggle switch. I use toggles in my 110, but remember needing to use a twin relay setup for my additional lights on the td5 to get them to come on automatically with main beam and come on with the dash switch.

miktdish said:

Just a fuse to the feed (30) will be OK - I like the relays with the fuse built in ...
85 is relay ground.

View attachment 314435

Click to expand...

It depends how much additional kit you are planning on fitting. I originally had the fused relays as above but as part of my rebuild moved to a full additional fuse panel (form blue sea) and a separate relay holder box for all the additional relays.