Combo relay, where is it?, Fog lights in trouble? Options

[Dr Evil]

My fog lights don't come on and the fuse blows every time I pull the switch. I have been tracing the schematics and have found a relay; Haynes pg. 158 item #27 "combo relay"

I do not know what it does or where it is located.
Is it needed for the fog lights?

thanks (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif)

[914-8]

your foglight switch has 3 wires running out of it.

Black/blue goes to the headlight switch.

Brown grounds to the emergency flasher switch.

Grey/Red goes to the relay. The relay is located on main fuse panel (roughly under the steering column). Unbolt the panel and pull it down, I believe it is the first small round relay on the driver's side (next to the buzzer).

Do you need a relay for the foglights? Probably not - you could rewire the system to bypass the relay. Oddly, the headlights aren't run through a relay on Porsches, but the fogs are.

But, IMO, it's always best to run fogs/headlights through a relay. Makes life a lot easier on your switches.

In any event, you almost certainly have a short somewhere in the foglight circuit that is causing your problem, not a problem with the relay.

[914-8]

also, the wire that runs out of the relay to the foglights is white/yellow.

[Dr Evil]

Thanks, I have all of that already maped out. I was just looking for the aformentioned combo relay because it has wires in common with the relay for the fogs; terminal 30 of the relay fog attaches to power end of fuse 1 where combo relay also attaches. Terminal 56 on the master light switch shares with both the fog switch terminal 15 and the combo relay.

I am not realy thinking the combo relay is the culprit, but I don't remeber ever dealing with it.

Here is some more info for the archives:
The light in the switch turns on and stays on even after the fuse blows meaning that the connection between 15 (power in from main light switch) and 31 (ground on other side of switch light) are being connected. K supplies power to the fog relay coil so I am thinking that he relay is crapped out (shorted). It is a simple circuit, luckily.

Thanks for the info.

[914-8]

QUOTE (Dr Evil @ Mar 14 2006, 10:13 PM)

terminal 30 of the relay fog attaches to power end of fuse 1 where combo relay also attaches.

I don't see that on the diagram.

"Terminal 56 on the master light switch shares with both the fog switch terminal 15 and the combo relay. "

I do see that one.

I'm with you - I don't know where the mysterious "combo relay" is physically located in the car. Doesn't seem to be on the fuse panel or the relay bd in the engine compartment.

Hopefully it is just the foglight relay like you suspect! That's the clean and easy fix.

[rhodyguy]

p128 mike. fig.9.22 shows the auxiliary relay as "c" on the top side of the fuse panel.

k

[Dr Evil]

QUOTE (914-8 @ Mar 15 2006, 11:22 AM)

QUOTE (Dr Evil @ Mar 14 2006, 10:13 PM) terminal 30 of the relay fog attaches to power end of fuse 1 where combo relay also attaches. I don't see that on the diagram. "Terminal 56 on the master light switch shares with both the fog switch terminal 15 and the combo relay. " I do see that one. I'm with you - I don't know where the mysterious "combo relay" is physically located in the car. Doesn't seem to be on the fuse panel or the relay bd in the engine compartment. Hopefully it is just the foglight relay like you suspect! That's the clean and easy fix.

Sorry, it was late. I meant terminal 85. 30 gets power from fuse 10. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

[Dr Evil]

Kevin,
That shows the fog relay which can be seen schematically on pg. 162, #53


...go fish (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

[rhodyguy]

(IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif) i thought you were trying to find where the relay "lives". i thought the picture might get you to the right address. so you swapped that relay out? got any 5s?

k

[Dr Evil]

Na man, I know where the fog relay lives. I was just looking for the combo one for the hell of it. I have never seen it, had to fix it, it could just be a figment of my imagination. It does share wires with the fog wiring, though (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

[rhodyguy]

you might have to pull the front bumper and inspect the wiring where it passes thru the body. lots of chaffing to be had up there. taking the fogs apart and having those little springs flying everywhere is fun. did this just start out of the blue, or after you did something?

k

[rhodyguy]

so...does the combo relay provide switching for the high/low beams? have you done the hl switch mod where you can run around with the fogs on and no headlights?

k

[Demick]

Combo relay does the hi beam/low beam switching. On a '73, it is tied indirectly to the fog light relay at the #1 fuse, and at the #56 terminal of the headlight switch.

The #56 terminal at the headlight switch provides power to the fog light switch when the headlights are turned on. The connection at the #1 fuse is where the fog light relay gets it's ground connection from - and when the high beams are switched on, this connection goes to +12V - which causes the relay to lose it's ground and turn off the fog lights.

Demick

[Dr Evil]

QUOTE (rhodyguy @ Mar 15 2006, 12:24 PM)

so...does the combo relay provide switching for the high/low beams? have you done the hl switch mod where you can run around with the fogs on and no headlights? k

I can't legally do this mod in PA as it is specified int he inspection procedures that the fogs opperate as they originally do on our cars (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

Combo = hi/low, that makes a lot of sence. I still do not know where it is. The connection at fuse 1 can not go to ground other than through the relay as it is the direct power in that the relay is communicating to the lights which have their own ground. I am gonna help a friend by doing his brakes today so it will not be until later or tomarrow when I can let yall know.

Thanks for all of the input.

[rhodyguy]

must be some 914 savy inspectors in pa (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif) .

[Dr Evil]

Not 914 savvy, it just states that the fog lights shall not remain on while the high beams are activated (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) I'll modify them later (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)


So here is the data:
It was a short at the drivers light connector. It would have been found even faster had I not transposed the circuit incorrectly (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif) I hand drew the circuit and swapped the wires for 30 and 85...there is time I wont get back. Since I took a break yesterday I had a much easier go of it once I got restarted.

Short story, I HAVE LIGHTS! They are everything that I always thought they would be and more (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

My relay layout is not the same as the picture in the haynes manual. My horn relay is in the fog relay position (scared the hell out of me when I shorted it out and sounded off the horn). I found the combo relay. It is on a connector that is loose and sits up behind the relay/fuse panel on the back of the dash.

Thats all for now, thanks to all of you for playing (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)