52 replies to this topic

[Rubbershorts]

5 terminal relays are the same as 4 position relays with a crossover terminal. powering 86 connects 30 to 87 as it disconnects 30 from 87a

Thanks Ethel.

[Rubbershorts]

I don't think the power source matters as much for old cars. It says in the diagram to use the power from the ignition switch (but not the ignition system i.e. individual coils on modern cars).
 
I've powered mine from a relay that's switched by the ignition switch. I've also powered it in the 12V accessory port (cigarette lighter) 
 
If you pick on of the fused terminals from the fuse board that gets 12V when the key is on then that will be fine

Brilliant, thanks Timmy.

[Rubbershorts]

I don't think the power source matters as much for old cars. It says in the diagram to use the power from the ignition switch (but not the ignition system i.e. individual coils on modern cars).
 
I've powered mine from a relay that's switched by the ignition switch. I've also powered it in the 12V accessory port (cigarette lighter) 
 
If you pick on of the fused terminals from the fuse board that gets 12V when the key is on then that will be fine

Brilliant, thanks Timmy.

Just had another look at the diagram. Why does it have two lives? It has a permanent and a switched. What did you use for your permanent live Timmy? Daz.

[gazza82]

I don't think the power source matters as much for old cars. It says in the diagram to use the power from the ignition switch (but not the ignition system i.e. individual coils on modern cars).
 
I've powered mine from a relay that's switched by the ignition switch. I've also powered it in the 12V accessory port (cigarette lighter) 
 
If you pick on of the fused terminals from the fuse board that gets 12V when the key is on then that will be fine

Brilliant, thanks Timmy.

Just had another look at the diagram. Why does it have two lives? It has a permanent and a switched. What did you use for your permanent live Timmy? Daz.

The relay? Switched is the circuit to operate it and requires little power - usually pins 85 & 86. Permanent is the main feed, 30 & 87, and can require heavier gauge cable depending on what is being powered.

[Rubbershorts]

I don't think the power source matters as much for old cars. It says in the diagram to use the power from the ignition switch (but not the ignition system i.e. individual coils on modern cars).
 
I've powered mine from a relay that's switched by the ignition switch. I've also powered it in the 12V accessory port (cigarette lighter) 
 
If you pick on of the fused terminals from the fuse board that gets 12V when the key is on then that will be fine

Brilliant, thanks Timmy.

Just had another look at the diagram. Why does it have two lives? It has a permanent and a switched. What did you use for your permanent live Timmy? Daz.

The relay? Switched is the circuit to operate it and requires little power - usually pins 85 & 86. Permanent is the main feed, 30 & 87, and can require heavier gauge cable depending on what is being powered.

Ah, thanks Gazza. Can I run both wires from the fuse box then? One switched, one permanent? With the permanent being suitable for over 5 Amps? 5 amps being the fuse size in the diagram?

[Ethel]

You've got an electromagnet inside  between 85 & 86. When it's powered it moves the contacts from the resting 87a to 87. There are many ways you can wire one up depending on the application.

 

For your application it may be best to power 85 or 86 from an ignition live (solid green) & earth the other. You can then run 30 or 87 off a permanent live and connect the other to your  sensor power input.

 

 

A quick google suggests a Bosch LSU4.9 is unlikely to draw more than a couple of amps, so it could probably cope with being wired direct to the ignition circuit.

[timmy850]

Honestly the relay is a bit of overkill for a < 5A device. If you’re using the existing fusebox to get the switched 12v and then adding a 5A fuse there’s likely to be no issues

[68+86auto]

The original switches and wiring don't seem to handle any additional load or even the factory loads. Heaps of small additional loads add up too. If it's the only additional load then you will probably get away with it though. It is best to fit a relay and you can then use it for other accessories too.