Relay question

Howard R · Post by **Howard R** » Thu Jul 21, 2005 3:22 pm

I recently put in fog lights in my '69. .They are connected to the wire in the engine bay that is controlled on the steering wheel stalk. I put in an inline fuse. I have had them on with the low and high beams... No problem. I've read rcommendations that a separate relay should be installed, or there is a possibility of frying wires. Now here's the question. What does a relay actually do? And, aren't the fog lights going thru a relay anyway?

Redtail · Post by **Redtail** » Thu Jul 21, 2005 4:17 pm

A relay acts as a second switch that controls the main power to the foglights. Usually relays have 4 spade connectors - one goes to ground, one to the foglights, one to the + battery terminal and one to the foglight switch. The minimal amount of power drawn from the foglight switch is only enough to keep the relay open (not enough to fry your wires). Power to burn the foglights is drawn directly from the + terminal of the battery, through the relay, and out to the foglights. Make sure these wires are 10 or 12 gauge and they [shouldn't] fry on you.

hope that was clear - correct me if i'm wrong here TR!

cheers

Howard R · Post by **Howard R** » Thu Jul 21, 2005 4:33 pm

Zack, since nothing is frying, I guess I'm OK. Wouldn't my additional inline fuse stop the frying if the wires were overloaded?

Post by **Datrock** » Thu Jul 21, 2005 4:48 pm

Hi Howard, If your fuse box is the single row I would use the relay setup, if it is the double bank fuse box you should be fine. The 68 and early 69 have both headlights going through one fuse the late 69 has a fuse for each headlight.
I used to run fog lightson my 68, I called them my life savers. I wired them separate from the light switch on a toggle. If you blow the headlight fuse on a early 69 all front lights will be out. Not cool... Bill

Howard R · Post by **Howard R** » Thu Jul 21, 2005 4:52 pm

Bill, I've got the double row fuse box. thanks for info. Also, isn't the inline fuse an extra safety factor?

Post by **S Allen** » Thu Jul 21, 2005 5:02 pm

Howard,

I would use a relay. I just did a write up and posted it to the main web site. I put one in for my cooling fan on the stroker. You can get there--------
http://www.311s.org/tech/electrical/relay.html

Pretty cheap insurance if you ask me.

Steve

Redtail · Post by **Redtail** » Thu Jul 21, 2005 5:03 pm

Howard,
The foglight switch in high windshield cars is on the stalk? cool. I ran the relay on my foglights just for added piece of mind, you can probably get away without it, but 35 year old wires are always suspect in my book.

If your inline fuse is on the wire the foglights draw power from, it should prevent your wires from frying between the fuse and the foglights. if it's close to the battery you should be pretty safe.

then again i carry around a fire extinguisher too. i'm just paranoid like that. This diagram is okay and basically shows how foglights are wired with a relay. Instead of grounding the lights back to the - side of the battery, most will ground themselves if they are mounted to a metal body panel.

Howard R · Post by **Howard R** » Thu Jul 21, 2005 5:08 pm

I gave some wrong info. The fog switch is on the headlight knob. When you turn the lamp light clockwise, on go the fogs. (i musta been thinking about my high beams)

Redtail · Post by **Redtail** » Thu Jul 21, 2005 5:09 pm

Does this diagram look like yours?

Howard R · Post by **Howard R** » Thu Jul 21, 2005 5:12 pm

Mine are grounded to the body. You sure know alot about these cars. I'm overwhelmed!

Redtail · Post by **Redtail** » Thu Jul 21, 2005 6:12 pm

Actually, as luck would have it, i just finished the wiring on my recent foglight install last night! so this is all fresh in my memory.

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