Fuse box relays

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George McMurtry
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Fuse box relays

#1 Post by George McMurtry »

Is the horn relay the same as the high beam relay? Horn relays can still be purchased but there are no original high beam relays available. If not the same, does anyone have an NOS high beam relay or a known good used relay?
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Edwin Ek
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Re: Fuse box relays

#2 Post by Edwin Ek »

Horn relay is black. Headlight relay is grey. At least on the later cars. They show up on eBay frequently.
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Greg Bryan
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Re: Fuse box relays

#3 Post by Greg Bryan »

The relays are different in operation as well = the light control relay is a two pole device where power is switched from one output to the other. The horn relay is a on-off device on its one output. With that said, the light control relay could be used as a horn relay, but the horn relay will not suffice for a light control relay.
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Albert Tiedemann
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Re: Fuse box relays

#4 Post by Albert Tiedemann »

Yellow relay function and part number? Anyone?
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Edwin Ek
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Re: Fuse box relays

#5 Post by Edwin Ek »

Yellow relay is for foglights. Function is to not allow high beams for headlights when fog lights are on.
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Greg Bryan
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Re: Fuse box relays

#6 Post by Greg Bryan »

Wes - the part number on the yellow relay is W-594/P/St - this is a normally-closed relay. It opens the circuit when energized
As Edwin says, the power to the coil comes from the high beam circuit, so when high beam is selected, the coil is energized opening the relay and cutting power to the Fog Light circuit.
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E Rutherford
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Re: Fuse box relays

#7 Post by E Rutherford »

Just to set the record straight on relays. Yes there is a horn relay, typically black. There is NOT a headlight relay. There is a Signal Light relay. The signal light relay only performs the function of flashing the highlights. A head light relay would would join the power to the device (battery to headlights as in Leoni's H4 relay system), thus reducing the load on the switch.

On early cars there is a button on the floor to switch from high to low beam. T5 and later it is built into the T/S switch.

You can use a modern relay to replace your signal light relay AND its hidden behind the fuse box cover (T6 and later).

Shameless plug - Klasse356.com sells them :D

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Hugo Karasawa
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Re: Fuse box relays

#8 Post by Hugo Karasawa »

What I understand in a 356C these relays are used:
I do not know what relays are used in earlier cars.
Attachments
Yellow relay fog lights SPST NC ( single pole single throw normally closed )
Yellow relay fog lights SPST NC ( single pole single throw normally closed )
Relay spst nc.jpg (5.35 KiB) Viewed 626 times
Black relay horn, SPST NO (single pole single throw normally open)
Black relay horn, SPST NO (single pole single throw normally open)
Relay spst no.jpg (5.17 KiB) Viewed 626 times
Grey relay Headlight flash signal, it is a SPDT (single pole double throw ) relay
Grey relay Headlight flash signal, it is a SPDT (single pole double throw ) relay
relay spdt.jpg (6.47 KiB) Viewed 626 times

Hugo Karasawa
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Re: Fuse box relays

#9 Post by Hugo Karasawa »

And if you have an extra grey relay you can use it instead of a yellow or a black , you will just have to connect it different.

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