i'm helping a friend repair the alarm system on his 70 vette. so far i have got this far, repaired a broken wire and the activation switch and i hear the relay if i have any door or hood open, which i should as that is making the relay circuit. my issue is the diagram from wilcox i do not think is correct. unless the horn for the alarm is isolated and a separate horn from the car horn.
the wiring diagram i have from wilcox does not look like it will work.
1. red wire from fuse to switch to horn to relay term 2 and that is one side of the relay coil.
2. then going thru the coil to term 1 and that then is white to a flasher relay and the door/hood pins.
3. the relay coil then passes the circuit to the common side of the contact inside the relay and then when a door is open to make the coil circuit the contact closes to a black wire going to a ground.

what makes no sense is term 1 white goes to a flasher unit and thru to a yellow wire that looks like it goes to ground at the horn. this circuit looks to me that it just can't work.unless the horn is isolated by itself, and not connected to the metal of the car. where does the black wire from the relay term 3 actually go? it says body lock pillar and that view is german to me.
maybe we are just activating the alarm system wrong? we closed the door and key locked it, then on the switch in back we turned to 3pm. and then i figure it is activated, am i correct? then i reached into the car and opened the hood and that should have activated the alarm correct! if this is wrong then can someone give me the steps to set the alarm provided the wilcox wiring is correct.

one more item if the horn is isolated by itself where might i find t? thanks for any help. bob p.

 

The alarm horn on my 73 is located under the rear deck behind the driver.

 

thanks i will have ron look in there for a horn. ir there is one in there and then it should be mounted on plastic so the wiring diagram might be ok. i see the 73 diagram looks almost the same and i thing the one on the wilcox site is wrong and the one i seen for the 73 is more accurate and show work. thanks

 

I probably wasn't clear about the location. It's under the rear deck outside behind the LR wheel.

 

I probably wasn't clear about the location. It's under the rear deck outside behind the LR wheel.
he doesn't have that on the 70 vette. he has 3 storage compartments in the cabin behind the seats the one behind the driver has the battery, behind the passenger has jack and the relay and flasher relay, the center one is smaller like a glove box.

i moved the wires and they travel under the carpet heading to the drivers door pin, but then i loos them. this is what i did saturday, i removed the factory relay it was bad, took a regular relay made a small harness and pushed the blades into the factory plug. then i used a saddle clamp and connected a car horn to the wires including the separate ground and put the horn in with the jack. now he as an alarm when the doors open and the hood goes up. not factory but works and is loud enough.

still would like to find the original alarm horn.

so in this repair i found a broken main power wire the key activation switch was bad and the factory alarm relay was bad. plus i believe the alarm horn is bad as i can't find it to tell for sure. so out f this whole mess the only originals thing i kept was the flasher relay. so i basically rebuilt his alarm system. thanks so far for the help

 

I checked my parts book illustration and it only depicts the 73 and 74 alarm horn which is where I said behind the left rear wheel up under the deck. That leads me to believe that the 70 alarm horn was in a different location. It never made any sense to me to have an alarm horn that was accessible outside the locked vehicle. Very easy to reach up under there and cut the wires. Maybe they located it in a fender well under the hood.

 

73shark i found it, was where you thought behind the drivers tire up above the muffler and on a plastic panel. boy was that a hard item to locate. nowhere on the web could i gat an answer. the c3 group told me the same thing as you did so now i have seen it and ron is going to attack it this week and bring it to me to see if i can repair it for him. he also need to get the hood pin switch and terminal ends along with the activation switch. then it is done. thanks for the help on this item bp.

 

Since I have side exhaust, I forgot about it being above the mufflers.