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I have just bought my first Corvette and absolutely love it. Firstly its a 72 matching numbers Corvette Coupe. Original colour being Targa Blue with original interior code 412.
I have a few things I need to fix up but firstly I would like to get the original alarm system working.
When I turn on with the key nothing happens, well at least I don't hear anything arming. Not sure whether it supposed to make any noises but feel free to let me know. If it does arm I would like to trigger it to check it is indeed working. If it isn't working where are some areas of the alarm I need to troubleshoot first?
Hi c,
Welcome!
What a great looking car!
The alarm is controlled by the keyed switch on the taillight panel. That's how you turn it on and off. It gives no signal that it's 'set' as you turn it on.
The alarm is triggered by 3 switches when it's on; the push switch mounted on the front door jamb (hinge pillar) on each side of the car, and a switch for the hood mounted on the cowl to the rear of the wiper door actuator.
The flasher and relays for the alarm are located in the jack compartment below the fiberboard tray.
The 'horn' for the alarm is mounted high and forward in the left/rear wheel well.
Have you checked to see if those parts are still on your car and that the plungers are operated as the door and hood push on them, and then release when the doors and hood are opened.?
Regards,
Alan
Welcome to the forum, and I agree with Alan, that 72 is a beauty.
Look forward to hearing more in the future as you enjoy your new car.
Alan did, as he always does, a great job explaining what to look for so you have heard from one of the best.
Let us know if we can help any further and best regards,
David Howard
AllC34Me
I have just bought my first Corvette and absolutely love it. Firstly its a 72 matching numbers Corvette Coupe. Original colour being Targa Blue with original interior code 412.
I have a few things I need to fix up but firstly I would like to get the original alarm system working.
When I turn on with the key nothing happens, well at least I don't hear anything arming. Not sure whether it supposed to make any noises but feel free to let me know. If it does arm I would like to trigger it to check it is indeed working. If it isn't working where are some areas of the alarm I need to troubleshoot first?
Corvetteoz,
Allow me to add my name to the list of admirers of your new car, it is gorgeous. Maybe you saw my post from a few days ago regarding the key lock and anti theft switch on my early '77. I believe you have the same setup. If the microswitch has failed or the key lock is not contacting it that could close the circuit which may have led the previous owner to disable it. If that is the case the bad news is those parts will be very hard to get at. On my car the engine is out as well as the brake booster so I have easy access, I can't imagine what it would be like otherwise. Good luck and enjoy your new ride!
I have just bought my first Corvette and absolutely love it. Firstly its a 72 matching numbers Corvette Coupe. Original colour being Targa Blue with original interior code 412.
I have a few things I need to fix up but firstly I would like to get the original alarm system working.
When I turn on with the key nothing happens, well at least I don't hear anything arming. Not sure whether it supposed to make any noises but feel free to let me know. If it does arm I would like to trigger it to check it is indeed working. If it isn't working where are some areas of the alarm I need to troubleshoot first?
Very Nice car! Enjoy it! My cars original color was Targa Blue but it's been repainted what I believe is Bryar Blue. And thanks for asking about the alarm. I haven't even tried mine yet but thank you Alan for your response. Now I know what to look for!
I'll check out all those areas of the alarm and report back what I find.
In the meantime i'd like to get some advice also on my interior. My interior code is 412 and it's all original. However I need to buy some new seat covers from the States and noticed the Willcox Corvette has a sale on this weekend. Can anyone let me know what the quality and colour of the seat covers from Willcox are like? Also they only list a Royal Blue seat cover for a 72, is this the right colour for the 412 code?
I have a few little odd jobs to fix on the car and would like to keep it totally original.
I had a look in all those areas. Seems everythings there for the alarm to work. Horn is where is supposed to be, all the actuators are there but whether they work not sure. Relay and flasher unit were where they were supposed to be also. Found a jack and wheel spanner in there to my surprise, looks original. In that compartment I found an orange wire and a black wire which had a male and female fitting that was not connected. They were the only 2 wires apart. I connected them and noticed the wires and plugs starting to get hot. I then disconnected them and wrapped some tape around them for safety. What are these 2 wires for (presuming the alarm)and why would they be getting hot because they look like they are meant to go together? Some sort of short somewhere?
Last edited by Corvetteoz; 03-03-2016 at 07:33 PM.
Reason: Add
Hi C,
Are the wires for the connectors for the flasher and relay in place? I can't tell from your picture.
You'll need to check with Willcox to find out which manufacturers seat covers they're selling.
There are only a couple of manufacturers who supply all the vendors that sell interior parts.
You'll want to make sure just exactly what blue you have in your car and Willcox should be able help you with that.
As far as keeping the car totally original….I believe you'll find that ALL the seat covers available now have a Comfort-Weave material that's noticeably different than the original. It's close, but not quite accurate.
So, check what's out there!
Regards,
Alan
The switch in the key lock is a pretty common failure spot. It gets a lot of water and road dirt up under there. Also, the alarm horn that Alan told you about in the rear can lock up or fail.
Hi C,
Are the wires for the connectors for the flasher and relay in place? I can't tell from your picture.
You'll need to check with Willcox to find out which manufacturers seat covers they're selling.
There are only a couple of manufacturers who supply all the vendors that sell interior parts.
You'll want to make sure just exactly what blue you have in your car and Willcox should be able help you with that.
As far as keeping the car totally original….I believe you'll find that ALL the seat covers available now have a Comfort-Weave material that's noticeably different than the original. It's close, but not quite accurate.
So, check what's out there!
Regards,
Alan
Hi Alan,
Yes the wires on the flasher and the relay are all there and connected. Would you know what the orange and black wires are for in that same compartment? 3 wires run off the horn also so it looks to be all there. I havent even tried to see if the alarm even works lol.
I tried the alarm and yeah it definitely does not work
Last edited by Corvetteoz; 03-03-2016 at 08:13 PM.
Reason: Add
- a pin switch at each door jamb in the back (not the hinge side)
- a pin switch for the hood (located above the wiper door actuator)
- a latching relay in the passenger side rear compartment
- a turn signal type blinking relay located next to the latching relay
- a horn in the driver's side rear 1/4 panel (above the muffler)
- a key switch in the rear panel to arm and disarm the system
This is how it works:
1) +12v is fed to one side of the key switch on the orange wire
2) when you arm the system by turning the key switch, the other side of the key switch gets +12v, which also sends +12v to one side of the horn and one side of the coil of the latching relay
3) when one of the three pin switches is closed (by opening the doors or hood) they send a ground signal to the other side of the coil of the latching relay, which in turn latches the normally open contacts closed, which sends a ground signal through the blinker relay on to the horn, which then honks in a cycle like a turn signal light does.
4) the only way to disarm the system is to turn the key switch to the off position, which breaks the +12v being fed to the latching relay, causing the previously latched set of contacts to open. Once set off, the alarm will sound until disarmed, or your battery runs out.
The whole thing works off ground signals. It may sound confusing, but it is really quite simple. When I did the body off resto to my car, I found that the alarm horn's diaphram was shot and the blinker relay was shot. Replaced the factory alarm horn with one called "the freeway blaster" that I found at the parts store, and replaced the blinker relay with a new one, and it works like a charm. The pin switches are often not working, so you might want to check them too. the door pins are servicable through the access door located in the rear wheel wells in front of the wheel. These pins have three wires on them: ground, alarm, and door ajar light; they serve a dual purpose, set off the alarm and light the door ajar light. The pin switch for the hood gets its ground at the wiper motor.
Hi C,
Are the wires for the connectors for the flasher and relay in place? I can't tell from your picture.
You'll need to check with Willcox to find out which manufacturers seat covers they're selling.
There are only a couple of manufacturers who supply all the vendors that sell interior parts.
You'll want to make sure just exactly what blue you have in your car and Willcox should be able help you with that.
As far as keeping the car totally original….I believe you'll find that ALL the seat covers available now have a Comfort-Weave material that's noticeably different than the original. It's close, but not quite accurate.
So, check what's out there!
Regards,
Alan
Originally Posted by 7t2vette
The alarm system consists of:
- a pin switch at each door jamb in the back (not the hinge side)
- a pin switch for the hood (located above the wiper door actuator)
- a latching relay in the passenger side rear compartment
- a turn signal type blinking relay located next to the latching relay
- a horn in the driver's side rear 1/4 panel (above the muffler)
- a key switch in the rear panel to arm and disarm the system
This is how it works:
1) +12v is fed to one side of the key switch on the orange wire
2) when you arm the system by turning the key switch, the other side of the key switch gets +12v, which also sends +12v to one side of the horn and one side of the coil of the latching relay
3) when one of the three pin switches is closed (by opening the doors or hood) they send a ground signal to the other side of the coil of the latching relay, which in turn latches the normally open contacts closed, which sends a ground signal through the blinker relay on to the horn, which then honks in a cycle like a turn signal light does.
4) the only way to disarm the system is to turn the key switch to the off position, which breaks the +12v being fed to the latching relay, causing the previously latched set of contacts to open. Once set off, the alarm will sound until disarmed, or your battery runs out.
The whole thing works off ground signals. It may sound confusing, but it is really quite simple. When I did the body off resto to my car, I found that the alarm horn's diaphram was shot and the blinker relay was shot. Replaced the factory alarm horn with one called "the freeway blaster" that I found at the parts store, and replaced the blinker relay with a new one, and it works like a charm. The pin switches are often not working, so you might want to check them too. the door pins are servicable through the access door located in the rear wheel wells in front of the wheel. These pins have three wires on them: ground, alarm, and door ajar light; they serve a dual purpose, set off the alarm and light the door ajar light. The pin switch for the hood gets its ground at the wiper motor.
Hope this helps.
Thanks mate. The system is quite simple but complicated for a novice like me. Would I be right in presuming the orange wire in the jack compartment is the wire that connects to the alarm key lock? As this got hot when I connected it might indicate there is a short in the lock.
The door ajar light comes on when the drivers door opens so it looks like that pin is working correctly. How do I check the other pins to make sure they are working with a multimeter?
Thanks mate. The system is quite simple but complicated for a novice like me. Would I be right in presuming the orange wire in the jack compartment is the wire that connects to the alarm key lock? As this got hot when I connected it might indicate there is a short in the lock.
The door ajar light comes on when the drivers door opens so it looks like that pin is working correctly. How do I check the other pins to make sure they are working with a multimeter?
I can't remember the wires in the jack compartment off the top of my head, but I can get back to you on that. There would be no short in the key switch itself because there is no intentional reference to ground at the key switch, it simply connects the two +12v wires together......unless somehow part of the switch is accidently grounded.
Each side rear door pin switch that turns on the door ajar light and sets off the alarm has 3 wires:
-ground reference
-ground to door ajar light
-ground to alarm relay
When the door is opened, the contacts close, and the 3 wires are connected together. Just because the door ajar light works, you can't assume the alarm is also getting the ground reference. I can't remember the wire colors at the pin switches, but you just need to identify which one from each side goes to the alarm relay, and use a meter to check for continuity between a good known ground and each wire to see if there is continuity when the door opens.
I can't remember the wires in the jack compartment off the top of my head, but I can get back to you on that. There would be no short in the key switch itself because there is no intentional reference to ground at the key switch, it simply connects the two +12v wires together......unless somehow part of the switch is accidently grounded.
Each side rear door pin switch that turns on the door ajar light and sets off the alarm has 3 wires:
-ground reference
-ground to door ajar light
-ground to alarm relay
When the door is opened, the contacts close, and the 3 wires are connected together. Just because the door ajar light works, you can't assume the alarm is also getting the ground reference. I can't remember the wire colors at the pin switches, but you just need to identify which one from each side goes to the alarm relay, and use a meter to check for continuity between a good known ground and each wire to see if there is continuity when the door opens.
I'm showing how much of a novice I am when it comes to multimeter use but anyway
Which setting do I put the multimeter on, presuming ohms?
Also if you could find out for me what the orange and black wire are for in the jack compartment which is pictured above, that would be a big help?
I'm showing how much of a novice I am when it comes to multimeter use but anyway
Which setting do I put the multimeter on, presuming ohms?
Also if you could find out for me what the orange and black wire are for in the jack compartment which is pictured above, that would be a big help?
Okay, here is a pic of the wires in my jack compartment:
My car is an early production '72, built in August '71, so yours may have different color wires if there were production changes later on. The only orange wire I have is for the light in the center rear compartment, and it has nothing to do with the alarm system. There is also a black wire the same gauge as the orange one that also goes to the center rear compartment light, which is turned on and off by a pin switch that the compartment door operates. The orange and black wire in your pic is for this light. When you connected them together, you connected a positive directly to a negative....you may have blown a fuse. On the left side of your pic, you can see where the compartment light goes, as well as more of the wiring for it.
So now I know the white wires are the ones that bring the ground reference from the 3 pin switches to the alarm relay and flasher.
For checking continuity, you would set your multimeter to the continuity setting if it has it; it looks like this:
Okay, here is a pic of the wires in my jack compartment:
My car is an early production '72, built in August '71, so yours may have different color wires if there were production changes later on. The only orange wire I have is for the light in the center rear compartment, and it has nothing to do with the alarm system. There is also a black wire the same gauge as the orange one that also goes to the center rear compartment light, which is turned on and off by a pin switch that the compartment door operates. The orange and black wire in your pic is for this light. When you connected them together, you connected a positive directly to a negative....you may have blown a fuse. On the left side of your pic, you can see where the compartment light goes, as well as more of the wiring for it.
So now I know the white wires are the ones that bring the ground reference from the 3 pin switches to the alarm relay and flasher.
For checking continuity, you would set your multimeter to the continuity setting if it has it; it looks like this:
Continuity test how-to:
Here is a helpful wiring diagram:
Mate your a legend. I'll have a look at it over the weekend.
In regards to the orange and black wire, maybe those were supposed to be connected to the middle compartment light instead of connecting them together, silly me, lucky I noticed it getting hot straight away.
Just checked the wires and you're right. The orange and black wires are for the light however the globe and posts have been removed.
The relay has 3 wires connected to it being red, black and white. The flasher has 2 white wires and a yellow wire. So it appears that the alarm components are all there.
Last edited by Corvetteoz; 03-03-2016 at 10:41 PM.
I could hear the pulse from under the door behind the passenger seat whenever I activated the system and opened a door or hood. But nothing from the horn. Upon inspecting that, the problem was pretty obvious, the horn was shot. I could not even turn the nut to remove it it was rusted bad. When I had a buddy put new magnaflows on, I had him remove that horn and replace it with a NOS one. Activated the system, opened the door, and Bingo, the alarm worked. I got lucky I think.
Beautiful car! But I must ask, what size are the tires, I will be replacing mine and like the look of yours very much. I am running 225 70 15's; they look good in the wells but yours look better. Thanks and Welcome!
I could hear the pulse from under the door behind the passenger seat whenever I activated the system and opened a door or hood. But nothing from the horn. Upon inspecting that, the problem was pretty obvious, the horn was shot. I could not even turn the nut to remove it it was rusted bad. When I had a buddy put new magnaflows on, I had him remove that horn and replace it with a NOS one. Activated the system, opened the door, and Bingo, the alarm worked. I got lucky I think.
Beautiful car! But I must ask, what size are the tires, I will be replacing mine and like the look of yours very much. I am running 225 70 15's; they look good in the wells but yours look better. Thanks and Welcome!
Thanks Kansas123
My tyres are 225/70/15 Indy Firehawk's. They are an excellent tyre and give a pretty smooth ride.
I'll check the alarm tomorrow and listen for any pulsation. Hopefully I get as lucky as you.
I could hear the pulse from under the door behind the passenger seat whenever I activated the system and opened a door or hood. But nothing from the horn. Upon inspecting that, the problem was pretty obvious, the horn was shot. I could not even turn the nut to remove it it was rusted bad. When I had a buddy put new magnaflows on, I had him remove that horn and replace it with a NOS one. Activated the system, opened the door, and Bingo, the alarm worked. I got lucky I think.
Beautiful car! But I must ask, what size are the tires, I will be replacing mine and like the look of yours very much. I am running 225 70 15's; they look good in the wells but yours look better. Thanks and Welcome!
Tried a test run of the alarm system today. Sadly I could not a get any pulse or any sign of even an alarm being on when I triggered the system. Where is the fuse for the alarm system?
I'm going to test the actuators on the doors and bonnet tomorrow. Could someone chime in exactly how I can test these with my multi-meter? I know how to test for continuity but exactly how to do it I'm not sure? Do I need the alarm turned on and exactly what wires do I need to test? Also which of the door actuators activate the alarm, the ones to the rear of the car or the ones at the front of the doors?
Tried a test run of the alarm system today. Sadly I could not a get any pulse or any sign of even an alarm being on when I triggered the system. Where is the fuse for the alarm system?
I'm going to test the actuators on the doors and bonnet tomorrow. Could someone chime in exactly how I can test these with my multi-meter? I know how to test for continuity but exactly how to do it I'm not sure? Do I need the alarm turned on and exactly what wires do I need to test? Also which of the door actuators activate the alarm, the ones to the rear of the car or the ones at the front of the doors?
Thanks all.
The ones in front are for the courtesy lights, the ones in the back are for the alarm. My car is not here and won't be for I don't know how long, or I would try to make sense of your situation and for that I apologize..... I will search my AIM and service repair manual and see if I can find something. Did you look at the fuse box and find anything labeled Alarm; I cannot remember seeing one on mine but it's been a while since I have looked. There may be an inline fuse in where the works are behind the pass seat. Here is something I just found:
03-03-2016, 10:42 AM
72 Alarm not working
