78 Alarm
Thread Starter
Racer
Joined: Dec 2004
Posts: 306
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From: Naples FL
78 Alarm
I still cant seem to get the alarm on the 78 to work. I replaced the switch under the hood and the ones on each door work properly. What else am I missing? Is the something I should check on the t-tops or is the door key switch bad?
Thanks
Tony
Thanks
Tony
Burning Brakes
Joined: Jul 2008
Posts: 876
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From: Canastota Ny
have you checked the horn in the ?rear? fender to make sure it works? my 79 alarm didnt work either. so i first tryed the horn. replaced it (front fender) and i now have a fully functioning alarm again!
before i knew anything about corvettes i went to look at one and asked the guy, does the alarm work? he turned the key and i heard thumping from the rear fender (75) that was the bad horn trying to go off. when he turned the key the alarm should have armed. with it going off it told me that one of the pin switched somewhere was open or bad. the horn will only sound when the switch is grounded
1. both doors
2. hood
3. both T-Tops
before i knew anything about corvettes i went to look at one and asked the guy, does the alarm work? he turned the key and i heard thumping from the rear fender (75) that was the bad horn trying to go off. when he turned the key the alarm should have armed. with it going off it told me that one of the pin switched somewhere was open or bad. the horn will only sound when the switch is grounded
1. both doors
2. hood
3. both T-Tops
Last edited by 1nicecorvette; Sep 22, 2008 at 09:38 AM.
Burning Brakes
Joined: Jul 2008
Posts: 876
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From: Canastota Ny
yup!! instead of a siren they used another horn. its will be in the rear drive side fender or if my years are incorrect it will be in the front drivers side fender.
its all just a simple circuit run through a relay off the key switch in the fender. key switch arms the system by leaving the circuit open. once any of the pin switches is opened (door hood t-top), that will close the loop to ground and hence the horn goes off.like a home window security system. but there is no timer so when the battery dies from the alarm going off all night, "it's over johnny, IT'S OVER!!"
Last edited by 1nicecorvette; Sep 22, 2008 at 09:47 AM.
Race Director
Joined: May 2006
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From: Dayton, Ohio
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Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
yup!! instead of a siren they used another horn. its will be in the rear drive side fender or if my years are incorrect it will be in the front drivers side fender.
its all just a simple circuit run through a relay off the key switch in the fender. key switch arms the system by leaving the circuit open. once any of the pin switches is opened (door hood t-top), that will close the loop to ground and hence the horn goes off.like a home window security system. but there is no timer so when the battery dies from the alarm going off all night, "it's over johnny, IT'S OVER!!"
its all just a simple circuit run through a relay off the key switch in the fender. key switch arms the system by leaving the circuit open. once any of the pin switches is opened (door hood t-top), that will close the loop to ground and hence the horn goes off.like a home window security system. but there is no timer so when the battery dies from the alarm going off all night, "it's over johnny, IT'S OVER!!"
The switch is integrated into the door lock so when you lock the door you're activating the alarm. T-tops weren't included in the alarm system until late 78. My April 78 Pace Car does not have them...think it was incorporated like July or something.
I was surprised to learn tho that the orange and yellow wires route back to the horn relay...well maybe the orange. They do terminate at the same block.
but the horn relay in 78, is hanging off the harness under the driver's side dash. Look between the steering column and the fuse box...I've just replaced it as well trying to get horn operational on this 78.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
What aqua is describing is correct for early C3s but its changed by 78. The alarm horn is located on the inside of the driver's side front fender...to the right of the washer fluid bottle.
The switch is integrated into the door lock so when you lock the door you're activating the alarm. T-tops weren't included in the alarm system until late 78. My April 78 Pace Car does not have them...think it was incorporated like July or something.
########################################
**************************************** ***********
I was surprised to learn tho that the orange and yellow wires route back to the horn relay...well maybe the orange. They do terminate at the same block.
but the horn relay in 78, is hanging off the harness under the driver's side dash. Look between the steering column and the fuse box...I've just replaced it as well trying to get horn operational on this 78.
The switch is integrated into the door lock so when you lock the door you're activating the alarm. T-tops weren't included in the alarm system until late 78. My April 78 Pace Car does not have them...think it was incorporated like July or something.
########################################
**************************************** ***********
I was surprised to learn tho that the orange and yellow wires route back to the horn relay...well maybe the orange. They do terminate at the same block.
but the horn relay in 78, is hanging off the harness under the driver's side dash. Look between the steering column and the fuse box...I've just replaced it as well trying to get horn operational on this 78.
The horn relay you referred to hanging above the fuse box is the relay for the regular horn activated by the button on the steering wheel and is 3 wire and is fused by the "stop/hazard fuse".
The relay for the ALARM is in the center console and is a 4 wire and fused by the "courtesy light fuse".
Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
I agree with the first part of your post but in the second part you started confusing the ALARM horn with the "get the heck out of my way" horn or the "hey baby your hot" horn.
The horn relay you referred to hanging above the fuse box is the relay for the regular horn activated by the button on the steering wheel and is 3 wire and is fused by the "stop/hazard fuse".
The relay for the ALARM is in the center console and is a 4 wire and fused by the "courtesy light fuse".
The horn relay you referred to hanging above the fuse box is the relay for the regular horn activated by the button on the steering wheel and is 3 wire and is fused by the "stop/hazard fuse".
The relay for the ALARM is in the center console and is a 4 wire and fused by the "courtesy light fuse".
But we must not be talking about the same anti-theft horn or perhaps I did not describe the location well. The NCRS tech guide describes its location as "installed in the driver's side fenderwell, aft of the windshield washer reservoir."
My wiring diagram (Olsen) shows a anti-theft protector switch. I take it that its the same as the relay. Shows the ground leads back to the anti-theft key switch (door lock key assembly).
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
DW...your absolutely correct on the location of the anti-theft horn relay. I pulled out my AIM and sure enough there it is along with the anti theft flasher.
But we must not be talking about the same anti-theft horn or perhaps I did not describe the location well. The NCRS tech guide describes its location as "installed in the driver's side fenderwell, aft of the windshield washer reservoir."
My wiring diagram (Olsen) shows a anti-theft protector switch. I take it that its the same as the relay. Shows the ground leads back to the anti-theft key switch (door lock key assembly).
But we must not be talking about the same anti-theft horn or perhaps I did not describe the location well. The NCRS tech guide describes its location as "installed in the driver's side fenderwell, aft of the windshield washer reservoir."
My wiring diagram (Olsen) shows a anti-theft protector switch. I take it that its the same as the relay. Shows the ground leads back to the anti-theft key switch (door lock key assembly).
On the "anti theft protector switch"-the switch is located at the door lock.If the door lock cylinder is "popped" out of the door the alarm will go off.Below is a pic from Wilcox showing the protector switch as item number 3.As you can see the protector switch "assembly" also holds the door lock cylinder in place.
[[So no the anti-theft protector switch is not the same as the relay.]]
Le Mans Master
Joined: Sep 2002
Posts: 5,236
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From: Myrtle Beach SC