72 Blazer under hood wiring?

[7D2N]

I could use some help identifying this set of wires (the looped set) they were not hooked to anything when I got the Blazer and this is where the end up under the dash. the 3 wires are black, blue and brown/white stripe. I'm trying to figure out what it does.

Thanks
7D2N

 

[bp71k5]

The relay you have circled is the horn relay. There should be a big fat green wire coming off of it that goes to the horn.

 

[7D2N]

bp71
no green wire there, does horn relay provide power to other items (beside the horn) or what propose does the horn relay serve?

Thanks
7D2N

 

[bp71k5]

bp71
no green wire there, does horn relay provide power to other items (beside the horn) or what propose does the horn relay serve?

It only powers the horn. Are there any wires coming off of that go to the horn?

 

[7D2N]

Brian,
The second pitcure shows how it is now, there is a horn wire but not from the shown relay. I have to solve a couple wiring issues I need to correct.

Thank you
7D2N

 

[bp71k5]

Brian,
The second pitcure shows how it is now, there is a horn wire but not from the shown relay. I have to solve a couple wiring issues I need to correct.

I went out and looked at mine. My horn relay looks different and has a different connector but is in the exact same spot.

I guess it's not the horn relay. I compared it with the other relays I have and it doesn't look like anything I have. Maybe take it off and look for a part number marking.

 

[70jimmy]

Looking at my Haynes manual the only brown with white wire used on the 67 to 72's begins under the dash where your second pic shows then goes into the bulkead connector on the inside of firewall, that bulkhead connector is held on by two screws that are diagonal from each other. Looks like this is actually the fuse panel, coming out of the same place where the brown with white stripe wire connects is a brown wire that goes back to to the cluster connector which has two sides and 5 wires on left and 7 wires on right. The brown wire is 2nd from the top, or if mounted sideways it would be on the bottom row 2nd from the right. This is the instrument cluster circuit and the brown wire is listed as Gen. Lp. In the engine compartment off the back of the fuse panel / harness connector this wire changes to dark blue and goes to the horn.

Your firewall wiring is a little different from mine. The only wire I have coming out the engine side of the firewall in that area is a black wire and it runs to the back of the vehicle into the plug for tailights, reverse lights, lic plate lamp etc. Also the manual shows a Brown wire coming from this area on the firewall to the tail and stop lamp harness connector.

A brown wire that goes straight from the fire wall to the left front marker lamp then splices to the right front marker lamp.

SO TO SUMMARIZE LOOKS LIKE THE BROWN WITH WHITE SHOULD GO TO THE HORN.
BLACK WIRE TO THE REAR OF THE VEHICLE TO THE TAILLIGHT HARNESS CONNECTOR
BLUE WIRE TO PARKING LIGHTS

Wiring on this old of a vehicle can be a crap shoot with many people splicing and rewiring all over the place and they don't usually pay attention to gauge color or route that wires should take.

Good Luck.

 

[70jimmy]

Right now I can't see very well under my dash, but in the next several days I will have to drop my computer to replace my speedo cable so I should be able to get a better look at the underdash wiring.

Ok heres the info:

On my jimmy the plug that goes into the horn relay is a 3 prong, two on top side by side and one centered below. It is like your relay but turned sideways to the left.

Top left plug closest to firewall (Black Wire) goes to the end of the curved Directional Signal Connector plug.

Top right plug furthest from firewall (Green Wire) goes to back of fuse panel

Center lower plug (Red Wire) goes to back of fuse panel

*******************************************************************
Haynes manual shows

20 guage black wire goes from horn relay to side of Dir. Sig. Conn. If you were looking at the connector like a backwards C it would be the top spot. Then on the other side of the connector 18 guage black wire goes to horn button

12 gauge dark green wire goes to back side of Bulkhead connector (fuse panel) left side 2nd row from left 2nd spot from top, then on the engine side it changes to 16 gauge brown wire and goes to voltage regulator, plug 4, they may be labeled F, 2, 3, 4

12 guage red wire splices into 2 wires both 12 guage red, one goes to back of fuse panel, 2nd row from left center top to bottom, other wire goes to light switch connector, which should be the plug on the back of the switch to turn headlights off and on.

That is the best I can do.

 

[70jimmy]

The curved plug in the upper right of the 2nd pic should be the Directional signal connector.