Topic: Good news and bad news
in Forum: C3 Electrical
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Whoa - quite a pic! I've been in that exact pose more than a few times in the last week!

|UPDATED|4/16/2013 11:17:42 PM (AZT)|/UPDATED|
I have a pic of my own now:
What's this relay looking thing? I think it or the wiring downstream from it is where my problem lies. It's mounted to the back side of the bulk head behind the seats - accessed by removing the tray from the pass side storage compartment. It's got a three prong connector, pink, white and black (two on the same prong). The pink has 12 volts between it and ground (both the white and the blacks appear to go to ground). It makes a loud click when hooking up the battery - always has. Can't seem to find it represented in the wiring diagram. But if I disconnect it my current drain is gone. 0.00 on the ammeter!
|UPDATED|4/16/2013 11:17:42 PM (AZT)|/UPDATED|
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
That, my friend, is the relay for the Alarm. So...if it is staying energized, sounds like you have an alarm that is always armed, for whatever reason. Goody! MORE troubleshooting! 
Or...if you're not interested in the alarm working, just leave the relay out.

Or...if you're not interested in the alarm working, just leave the relay out.

Joel Adams
C3VR Lifetime Member #56
My Link
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Excellent! Problem solved at least for now - think I'll leave it out. Haven't had a working alarm since I bought the car 11 years ago. PO said it would drain the battery if it was used - guess he was right! I messed with the fender switch sometime in the last year in a half-hearted attempt to get the system working, but it looks like all I did was make it so it was always energized. Eventually I will get the system working, but will save that project for another time!
Thanks Joel and others for the advice and encouragement!

Moderator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Dave, do you have the Service Manual for you car? It has the alarm system troubleshooting info in it. I have the info too, if ya need it.

Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
So glad you found it Dave! Now I might know why the alarm switch is missing on mine inside the front fender; probably was draining the battery! I still have the relay and flasher in the jack compartment but no switch behind the key lock on the fender.
2012101154624r.jpg)

Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
Dave - Glad you found something - I'm curious now.....going out to pull the tray out of my compartments to take a look.
Joel...it was only a matter of time before that made it on the forum...
or was it out here before & I missed it? 



Thanks all! I'm glad I found it, too! Now I can start putting stuff back together and hopefully get it out on the road for a show here two Saturdays from now.
Joel: I don't have the service manual. I just have the AIM and a Haynes manual. The Haynes does have wiring diagrams, but I don't think it has troubleshooting for the alarm. Any chance you could email it? I'll PM you with my address.
Greg: that fender switch is problematic. I'm 90% sure that's the problem with mine. It's one of those kind of switches that its default position is closed if I remember right. The little button on it has to be under constant pressure to keep it open. It's the same switch that is used in both headlights, I think to trigger the warning light if they're not popping up. Good luck to you in getting the alarm working. Always been on my long range plan....
Bobbi: Thanks for the encouragement and good luck to you, too! Electrical drain is a pain! But not an insurmountable problem if you know how to use a multimeter.

Moderator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Case75 said: So glad you found it Dave! Now I might know why the alarm switch is missing on mine inside the front fender; probably was draining the battery! I still have the relay and flasher in the jack compartment but no switch behind the key lock on the fender.
Just to be clear, the key cylinder you insert the key into on the fender IS the alarm arming switch. The other, second switch is the "Anti tamper" switch. Its purpose is to set the alarm off if anyone removes, or otherwise tampers with the key switch. The key cylinder switch will have two wires coming right out of it, and the anti-tamper switch(which is in fact the same switch for the headlight warning) fits into a bracket underneath the key switch, and is pressed up tight against the key switch.
Barb, that fun pic has been posted here before....you musta missed it...

Dave, I'll get what info I have together and send it your way.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
The harness that goes to the rear has one larger gauge orange wire which feeds both the box light and the main interior light (they work independently ground wires). There is a splice in the stock harness in that bundle, if I remember right, under the door sill plate about mid-way of the seat, and the larger gauge wire turns into two smaller gauge orange wires that go to the interior and box lights. My interior light experienced a minor short, and that orange wire actually melted all the way up wire to the splice but didn't blow the fuse. I was working on the car with the door open, and realized I had a problem when the interior filled with smoke. :(
Ironically, the two footwell lights (on the same fuse) continued to work. It was a good demonstration that a short can draw current but leave the rest of the circuit functional. Was enough current to melt the wire, but not blow the fuse. Those orange wires are hot even with the doors closed, but current won't normally flow unless the doors are open which makes the ground path (or the small switch is made closed when you open the storage compartment).
Long story short: if that wire has a nick in it and it finds a ground, you'll slowly drain the battery.
The rear harness unplugs close to the fuse box. You can pull it, remove the orange wire with a small screwdriver and plug the rest back in. That'll disable the rear two lights. See if you still have a current draw.
Sorry this is so wordy. But I'm an Engineer: why use five words when five hundred will do? :)
Ironically, the two footwell lights (on the same fuse) continued to work. It was a good demonstration that a short can draw current but leave the rest of the circuit functional. Was enough current to melt the wire, but not blow the fuse. Those orange wires are hot even with the doors closed, but current won't normally flow unless the doors are open which makes the ground path (or the small switch is made closed when you open the storage compartment).
Long story short: if that wire has a nick in it and it finds a ground, you'll slowly drain the battery.
The rear harness unplugs close to the fuse box. You can pull it, remove the orange wire with a small screwdriver and plug the rest back in. That'll disable the rear two lights. See if you still have a current draw.
Sorry this is so wordy. But I'm an Engineer: why use five words when five hundred will do? :)

"Let them that don't want none have memories of not gettin' any."
- Brother Dave Gardner
Thanks for the info and advice - definitely had planned to isolate the two lights in the back but now I am fairly confident it's the alarm circuit which uses the same fuse. Joel sent me the wiring diagram for the system and it seems simple enough that I think even I will be able to troubleshoot and hopefully get it working like new. (I am an engineer, too, but not an electrical engineer). I ordered a new anti-tamper switch from Bair's yesterday - will start there! Would love to someday get all the retro 70's features of this car working someday, like the rinky-dink alarm system and all the buzzers and warning lights - getting there one step at a time.
in Forum: C3 Electrical
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