Turn Signal, Brake Lights and Horn

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jr78c15

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Rockport Texas
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Harold Fisher
Truck Year
1978
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c15
Engine Size
350
78 GMC High Sierra

I replaced my turn signal cam and after installation the turn signals, brake lights and horn does not work. The emergency flashers work. When installing new cam I did hit the horn and think this might have something to do with this. Sorry in advance if this is a stupid question but I'm new to this.

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bucket

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Have you checked the fuses under the dash?
 

jr78c15

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Harold Fisher
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1978
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c15
Engine Size
350
I see a fuse for tail lights but not horn and turn signals. All fuses look intact.

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Matt69olds

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Your turn signals are most likely on fuse A, what the manual calls traffic/hazard? Any chance the turn signal switch connector at the base of the column is unplugged? Can you hear the horn relay click when you push the horn button?
 

bucket

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Also check that you are relying on the correct diagram. That one states '77 and '80. '78 and older were glass fuses, '79 and later were blade fuses. Iirc, the fuse boxes are organized a little different.
 

jr78c15

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Dec 10, 2019
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Location
Rockport Texas
First Name
Harold Fisher
Truck Year
1978
Truck Model
c15
Engine Size
350
No clicking when pressing the horn, I will check the connection this morning. This diagram looks like the one in the truck but I’m not positive it’s the correct one.
 

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