Relays in the '74 electrical circuits

Bmachine

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In another post, Chris asked:

It would be good if you posted pics of the 74 relays like I did so we know the locations as well.
Since I am trying to make sense of my electrics as well, I thought I would take a few pics and trying to correspond them with the diagram. Again, this is 74 only as the previous years have several differences. Also, mine started life as an automatic so that will come into play as well.

Engine bay above the battery from left to right as seen from the motor:

The leftmost pic is a relay that is "hanging" there and was not secured anywhere when I got the car. It is possibly the automatic choke relay (117 on diagram)
The we have the group of 3 attached to the inner fender.
The left one is the fog lights which also affects the high beams (15 on diagram)
The middle one is Horn (16 on diagram)
The right one is for the AC fan (not on the diagram that I can see)

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Bmachine

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Under the dash, nest to the fuse box:

6 relays attached to inner fender:

From L to R:

1: ?
2: Load shed relay for window system (114)?
3: Load shed relay for window system (114)?
4 (big black one): ?
5: ?
6: Possibly Starter relay for automatic (91) ? As you can see in the pic, here it is removed from its bracket and there is a single black wire connected to it

The 7th is laying on the fuse box door. No idea what it is at this point.

Needless to say, any help filling the blanks would be greatly appreciated.
Unidentified so far are:
Low beams (18), Hi beams, Load shed relay (38)

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Bmachine

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Credit due to these threads which shed lots of info:



 
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Bmachine

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According to sfDon in the first thread above:

"I believe the high beam filaments act as the ground at pin 85 on the fog light relay.
Once the high beams are turned on and the lows are off the ground becomes a positive at that pin which gives the relay a positive at pin 85 and no longer a positive at pin 86 deactivating the relay.
Note pin 85 is the connector with 3 white wires, 2 that go directly to the high beams and one from the high/low beam switch. Also note that the right high beam wire in the schematic has a labeling error or errata with its reversal of the description of wire color from “ws “ to “sw “.
The positive at pin 86 comes from the fog light switch directly from the low beam circuit.

So- low beams power the fog light switch which activates the fog light relay.
With low beams off- no fog lights.
With high beams on- no fog lights
Only with low beams on and fog light switch on do you get fog lights.
And if you wire low beams to stay on with high beams you still get no fog lights.

The “toggle” is fog lights go off when low beams go off or high beams go on."
 
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HB Chris

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I don’t know as much about 74s but the wiring diagram colors will tell what is what pretty easily. Under dash relay with yellow wires (unique to 74) is always low beam, hi beam is always white next to battery. Never seen an AC relay by battery but that is what you have. 74 diagram has window load shed relays, just match the colors. Horn is unique also, must be the violet brown. Don’t know why you have relay where regulator once mounted for the alternator either.
 

Bmachine

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Yes. In theory it should be easy to match the colors from the diagram to the actual wires. But for some reason I find a lot of discrepancies between the diagram and what I have in my car. I’m almost wondering if the diagram is not the right one. I’m using the one you sent a while back.
 

Ohmess

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Bo -- You probably know this, but the toggle feature of the fog lights is to meet federal regulations as to how many lights you can have illuminated facing forward at any one time.

Some comments on your pictures:

-- As Chris notes, the relay hanging where the voltage regulator had been in the older cars looks like a modification to your car based on the screw and nut used to hold it in place. My guess would be that this was done to allow for the use of a newer relay.

-- If the connection to the flying relay mount in your eighth picture is function, is some type of hack fix. It is not a safe connection with this much of the connector exposed. Moreover, that type of spade connector is designed to snap into place once connected so as to prevent it slipping out of place. You would not use that type of permanent connector on a relay mount because you have to mess up the connector, and possibly the relay mount, if ever you needed to change it. And, of course, that type of relay mount is intended to be fitted into a sheet metal slot somewhere.

-- The connector with the two black wires laying loose in your last picture needs a home. It is difficult to see the connector, but it looks like one of those female connector that mates up to an opaque white connector.

Are you trying to fix something specific?
 
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HB Chris

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OK, I’m back from the Targa. Under the dash the two relays with red, green/red, green and brown are the two window relays. Your low beam relay next to them has red, green, yellow/white and brown.
 

HB Chris

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The relay where the regulator belongs is hi beam, remove relay and see if hi beams can flash. Hi beam is white. Relay in middle is horn, unplug and test, green/yellow, brown/yellow, red, black. Forward most relay looks like A/C relay which you stated, I wonder if all 74s have one there, that’s a new one for me at least. The round connector under the dash is backup lights, diagram shows only three pins, you have five, but colors are correct for backup, green/white, blue/white and grey/red.
 

HB Chris

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Hazard relay was is laying on hood access door, black/white, green/violet, brown, green yellow. Large rectangular relay by window relays is the wiper washer control relay. Black/blue, black/red, brown/black, black, brown/red.
 

HB Chris

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In front of wipe wash relay is the main load shed relay, two large red wires, brown, green/violet, green. Edit: empty socket is for Automatic only starter relay, black and brown/black. Choke relay had green/white, black, green/blue but this was on booster mount I believe. You are on your own from here!
 
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sfdon

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Confirming Chris-
In dash
3 load shedding relays
Wisch wasch (washer) relay
Low beam relay
Automatic Tranny starter relay
Hazard relay


Engine bay

Horn relay
Hi beam relay
Fog relay
AC relay
 

Bmachine

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For some reason my “Fog lights” (which we now know also controls the hi beams) is empty. (See pic in first post). Looking through my box of parts I have found a Hella RA002 566-03. Doing a search on the site, I found several posts which said something to the effect of “If the pins fit in the holder and it is 12volts, it will work fine.” This sounds pretty far reaching but if that is the case, am I correct to assume this one will be fine for that Hi beams relay?

8C58C3E5-2A11-44F0-8B6D-DA9835658603.jpeg
 

HB Chris

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The small can relays were used on 2002s so they can be used but the 74 turns off fog when hi beam selected so it must be a unique relay. Do you have hi beams?
 
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