75 Alarm problem
Thread Starter
Instructor
Joined: Mar 2013
Posts: 180
Likes: 21
From: Chesterfield Mo
75 Alarm problem
I replaced the alarm switch inside the fender and replaced door switches. I made sure the switch button was depressed against the lever turned by the key as specified in the AIM manual. Now the alarm horn sounds when I turn the key to arm the system. The door switches appear to be adjusted correctly as the door ajar light functions as it should. I think the hood switch is adjusted correctly. What would make the alarm sound when I turn the key to arm it?
In general can anyone explain how the system is supposed to work.
In general can anyone explain how the system is supposed to work.
Le Mans Master
Joined: Aug 2006
Posts: 7,411
Likes: 1,551
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
A few things to check!
Have you checked the relay?
Could it be that the contacts are stuck closed?
Or has the flasher gone bad?
Could it be that the contacts are stuck closed?
Or has the flasher gone bad?
Thread Starter
Instructor
Joined: Mar 2013
Posts: 180
Likes: 21
From: Chesterfield Mo
i don't think it has anything to do with the relay or flasher as it honks the horn repeatedly. I have checked that the door and hood switches are depressed when the key is turned to set alarm. Turning the Key on the fender switch causes the horn to activate.
How do I check the fender switch to see if it is defective or not adjusted properly. I don't understand how turning the key to set the alarm causes it to honk and when I turn the key to off the horn stops honking.
I suspect the new fender switch but it is so hard to get to I don't want to try to readjust or replace it unless I have to.
How do I check the fender switch to see if it is defective or not adjusted properly. I don't understand how turning the key to set the alarm causes it to honk and when I turn the key to off the horn stops honking.
I suspect the new fender switch but it is so hard to get to I don't want to try to readjust or replace it unless I have to.
Pro
Joined: Dec 2015
Posts: 576
Likes: 107
From: colo
If you look at the exploded diagram above, it shows a tab " B" that should depress the button "A " when armed.
Check and make sure the " 1 " is forward enough to depress " A ". If it is, then one of your contacts ( door or hood ) is setting the alarm off.
Check and make sure the " 1 " is forward enough to depress " A ". If it is, then one of your contacts ( door or hood ) is setting the alarm off.
Safety Car
Joined: Oct 2016
Posts: 3,730
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From: Way too effing close to the city.......NRA Life Member!
2022 C3 of the Year Finalist - Unmodified
gsimon767......just curious how this was resolved. I have the same issue with my low mile 1976 C3. It was re-painted 3 years ago so I'm wondering if a wire were left off or something was not put back correctly. When I turn the key/switch on the fender, the horn sounds within a second or so? It was my deceased cousin's car so I can't ask him about previous issues. He owned it for 25 plus years.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
i don't think it has anything to do with the relay or flasher as it honks the horn repeatedly. I have checked that the door and hood switches are depressed when the key is turned to set alarm. Turning the Key on the fender switch causes the horn to activate.
HOW did you check this???? IF you LOOK carefully at the wiring diagram...you will need to check the WHITE WIRE at the FLASHER and see if it is grounded or not. IF it is GROUNDED...then your alarm will go off when you turn the key....simple as that.
How do I check the fender switch to see if it is defective or not adjusted properly. I don't understand how turning the key to set the alarm causes it to honk and when I turn the key to off the horn stops honking.
IF you want to check the switch at your fender switch....you can remove the connector and using an ohmmeter...make sure the switch is OPEN. IF the switch is closed and you get an ohm reading...then it is NOT adjsueted correctly.....it MUST be open.
I suspect the new fender switch but it is so hard to get to I don't want to try to readjust or replace it unless I have to.
HOW did you check this???? IF you LOOK carefully at the wiring diagram...you will need to check the WHITE WIRE at the FLASHER and see if it is grounded or not. IF it is GROUNDED...then your alarm will go off when you turn the key....simple as that.
How do I check the fender switch to see if it is defective or not adjusted properly. I don't understand how turning the key to set the alarm causes it to honk and when I turn the key to off the horn stops honking.
IF you want to check the switch at your fender switch....you can remove the connector and using an ohmmeter...make sure the switch is OPEN. IF the switch is closed and you get an ohm reading...then it is NOT adjsueted correctly.....it MUST be open.
I suspect the new fender switch but it is so hard to get to I don't want to try to readjust or replace it unless I have to.
I bet your under hood switch is the problem. Those are very touchy and can fail.
DUB
Last edited by DUB; Oct 9, 2016 at 06:11 PM.
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Thread Starter
Instructor
Joined: Mar 2013
Posts: 180
Likes: 21
From: Chesterfield Mo
gsimon767......just curious how this was resolved. I have the same issue with my low mile 1976 C3. It was re-painted 3 years ago so I'm wondering if a wire were left off or something was not put back correctly. When I turn the key/switch on the fender, the horn sounds within a second or so? It was my deceased cousin's car so I can't ask him about previous issues. He owned it for 25 plus years.
It seems that if a thief punches out the keyed switch they will cause the button on the anti tamper switch to release and sound the alarm. Crude but effective.
There are two wires to the anti tamper switch. I assume it can be bypassed if the two wires are connected. I ordered a new switch and made sure the button was pressed in tIghtly. It is very difficult to get to but can be done by reaching under and arround the master cylinder to loosen the nut under the switch.
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
how about the switch under the hood, that goes off if the hood is raised?? (my 76 has it , don't know what year yours is.) Make sure you have the correct switches, also.
Last edited by lvmyvt76; Oct 10, 2016 at 08:23 PM.
Safety Car
Joined: Oct 2016
Posts: 3,730
Likes: 293
From: Way too effing close to the city.......NRA Life Member!
2022 C3 of the Year Finalist - Unmodified
I replaced the alarm switch inside the fender and replaced door switches. I made sure the switch button was depressed against the lever turned by the key as specified in the AIM manual. Now the alarm horn sounds when I turn the key to arm the system. The door switches appear to be adjusted correctly as the door ajar light functions as it should. I think the hood switch is adjusted correctly. What would make the alarm sound when I turn the key to arm it?
In general can anyone explain how the system is supposed to work.
In general can anyone explain how the system is supposed to work.
Last edited by OLE442; Oct 25, 2016 at 09:05 PM.
Thread Starter
Instructor
Joined: Mar 2013
Posts: 180
Likes: 21
From: Chesterfield Mo
It sounds like even though you think the button on the fender switch is pushed in, it is not. I had to wedge a large socket between the edge of the mounting shelf and the switch while I tightened the nut on the bottom of the switch. The socket kept the button depressed while tightening the nut. I had the exact same problem you are having. You can take the switch out of the circuit by unplugging the switch wires. If you can then turn the key without the alarm sounding the switch button is not depressed enough. It takes a lot of pressure to hold the button in.