Battery drain/electrical short.

[vettte_wings]

After three days my battery is dead. I know there is a short somewhere, but finding it is the hitch.

I noticed that after I disconnect the battery the clock runs for about three minutes and then stops, but it cant be the clock if its shuts down after three minutes, "right".

Any idea on how to make or buy a tester to find what’s running after the 77 Vette is shut off, what would be the proper procedure on checking the system out?

 

[vmrod]

Although I never did this YET (I think I may have a power drain too, but my car is on a 'trickle charger'), here is what I read on a previous thread.

1.) Disconnect the negative side of your battery.
2.) Install a test light between the negative side of the battery and the negative battery cable.
3.) (If the light is on, you have a drain.)
4.) Unplug all of the fuses on the fuse block. (Hopefully the light will go off at this point.)
5.) One at a time, plug a fuse back in place, and see if the light comes on. (Note which fuse it is, leave it unplugged, then go to the next fuse.)
6.) Hopefully most fuses have been plugged in, and the light is off. The remaining circuits (the ones that cause the light to come on) are the one(s) with the power drain.

The clock will cause a small drain. You can always disconnect it, and see if the clock circuit still has a power drain. Also remember that a 1977 had a car alarm system installed, and this may be causing a drain as well.

I have a 1966-1976 manual at home. Most of the wiring diagrams are pretty much the same for a 1977. (I own a 1977 myself.) If you narrow the drain down to a particular circuit, perhaps I can help trouble-shoot further.

 

[Bob Chadwick]

I had a clock in a mid 70's car that ran on a spring that would be would by electricity every once in a while (It used to set the alarm off everytime it wound the clock). I don't know of the vette clock is the same but that would certainly explain the strange behaviour of your clock.

 

[vettte_wings]

Thanks for the troubleshooting tip vmrod and it worked.

Clock, Lighter and Courtesy fuse, 20 Amp was the culprit.

Bobchad the strange behavior of my clock might be the fix.

The alarm must be on its own circuit, I didn’t see the fuse for it or maybe passed it up in the process.

At this time it doesn’t work, but it will.

You guys have the low down on the alarm?

 

[Bob Chadwick]

Yeah, get a good aftermarket one. The one in the 77 is just a siren that rings until the battery is dead. Get an aftermarket that has a kill switch, is time limited, etc. I had one put in for about $350 that has all that plus somekind of sensor that will detect if someone puts their hands inside the open t-tops.

Bob

 

[vmrod]

I agree with Bob.
The original alarm would sound if either the doors or hood were opened, if the T-tops were messed with, or if the on/off switch was tampered with (I think).
Unless you want originality, I would not use it either.

 

[vmrod]

If you really want to hook it up again, I have a shop manual. It's for a 1976, but I think it's close enough to use for a 1977.

 

[Bob Chadwick]

I played with mine until I realized its limitations.

Mine has the main power wire to the horn disconnected and the hood switch removed. When you connect the power to the horn it immediately goes off.

Someone posted at one point that the most likely cause of failure are two relays under the center console. One is under $10 and available from GM. The other is about $30 and can be one of two or three types, not all of which are available, though supposedly NAPA can test and if necessary, come up with a replacement.

The electrical troubleshooting manual has a pretty good explanation as well and I'd be happy to copy the couple of pages and get them to you.

Bob

 

[vmrod]

Bob,
I noticed that there's a small button. It looks like a pushbutton with a rubber boot on it. It is located in the area of the factory alarm key switch. I think the button has a black and white wire connected to it. I'm pretty sure this is part of the alarm system. It either sits next to the key-switch (acts as a tamper switch), or it is some kind of alarm bypass switch (which sounds corny, because smart crooks would simply press the button).

Maybe that pushbutton has been removed or is not in it's proper place. But really, it doesn't matter much unless you want originality. The new alarms are far superior.

(On another note...I will be drawing upon your A/C and heater vent experiences in the next couple months) Your web-site is helpful.

 

[Bob Chadwick]

I don't have that button and I didn't notice it in the electrical manual. Mine is a later (?) model that had the switch built into the door lock. It doesn't matter as I have already added the remote system. I need to add the electric door locks and have it hooked to the alarm and I'll have a complete keyless entry system.

Glad my site is helping. The HVAC system was one of the first items I tackled simply because it was too hot to drive here in Atlanta. In some ways it is the only area that I feel that I have a good understanding of.

Good luck when you attempt it. With a basic understanding it is not too difficult, its just difficult to access.

Bob

 

[vmrod]

Try the humid heat of Louisiana!
Well I'll remove my entire dashboard soon. It is a little easier for me, because I don't have a roof above me. (I luv my vert)

First, I am dying to take it out around the block. I am so close! So far, the brakes, steering, and rear suspension is better than ever! I can't wait to try it out. Then after a few quick drives, I'll yank her insides out, patch up the vacuum lines and adjust the controls, then add lots of insulation/underlay. Right now, I'm still overjoyed that I finally installed my oil press sending unit in a nice location, and also replaced the front and rear transmission seals.

 

[Bob Chadwick]

The passenger side, center and upper pad are easy. It is the driver side pad that is the fun one. Tight spaces, all those wires and the lip on the steering wheel that the pad has to go under. Get your self one of those cheap mirrors on the telescoping arms. If you put a light on the floor shining up this makes it easier to see what you are doing when you put it back together.

Bob

 

[vmrod]

OK. Do I need to totally remove the driver's side dash? Or can I leave it on and just use the mirror idea? I guess that I just need to make sure that the vacuum lines are hooked up, and any vents close all the way. What do you suggest?

 

[Bob Chadwick]

You may not shouldn't have to remove this pad. If your headlights work, then you are way ahead of the game on this pad. If the don't, you can access the vacuum lines that come to the headlight switch with the top pad out. They then go from the switch down behind the lower pad to the bypass switch under the dash. If necessary, you might be able to even change out the headlight switch with the pad in. I had to replace mine because the dimmer was broken though it was no problem with the driver's side out. If you have to replace the vacuum lines, I would assume that you could bull them behind the pad.

As to the heater controls, I had vacuum coming into my system so I don't know if the pad will have to be removed if you need to trace this source. As I reall all of the components were accessible with the tunnel skirts off. You may have to remove this pad if you need to replace the actuator on the left side of the air distributor that switches between heater, vent and defroster.

Bob

 

[vmrod]

Although my headlights are not popping up like they should, I am sure that my headlight switch and override switch are working properly. A couple months ago, I removed both of these items, and I checked the vacuum lines. One prob with the headlights is a crushed 'control' vacuum line. I'm pretty sure my actuator (or seals) and control relays need replacing. But I'll troubleshoot those things later.

You mentioned something about an actuator that switches between the heater, vent and defroster. Where is this located?

 

[Bob Chadwick]

I had problems crushing the headlight supply line when I put the driver's side pad back in. Nothing a good yank didn't take care of.

The actuator is on the low left side of the air distibutor that is right behind the radio and center air vents. It is behind the driver's pad but is somewhat accessible from under the dash pad. Whether you could get it out to replace it, if necessary, without removing the driver's pad, I don't know. Mine was creaking, etc., and has become much better just with use.

 

[vmrod]

Well, it sounds like I can probably leave the driver's side pretty much alone. Right now, it is still a little loose. (I never re-screwed it from replacing my headlight switch.)

It sounds like, if I remove the upper dash pad, the passenger pad, and the center console, I should be avle to get to everything I need.

 

[vettte_wings]

Bob, I noticed the carpet is being replaced on your web sight. What is the purpose of that white piece of tape ruining down the passenger side on the top left picture. I noticed too that in the bottom right picture there is a board behind the speakers, is that something you put in place or is that in the car already. Anything I need to check when the carpet is out?

I bought some carpet at the Chevy Vette Fest in Chicago, and don’t remember seeing that piece of gray insulation (bottom left picture on that riser) in the box. I had bought that rubber based sound deadener from mid america to put down first. As I’m doing this carpet restore, I'll get a sound system in and get the 8 track out. I figure this will be a good project as old man winter takes away my summer fun.

 

[Bob Chadwick]

I think the white stripe you see running down the side in the top left picture is sunlight amongst shadow.

I mounted the speakers on the board, carpeted the board and then wedged the setup in the back to hold the speakers in place. I trimmed the depth of the speaker boxes before putting them on the board to leave enough room for the t-tops with the speakers in place.

I put the insulation there to insulate from the heat and noise. As to heat, it is probably overkill as that area never got that hot. It was easy and I figured why not as every little bit helps.

The stereo upgrade was easy. The dash pad comes out with no problems and both speakers can be upgraded. The trick was coming up with something to put the speakers in the rear, hold them in place and allow room for t-tops.

This post has some info on what others have done with rear speakers. http://www.corvetteactioncenter.com/forums/showthread.php?s=&threadid=12797&perpage=15&pagenumber=1

Bob

 

[vettte_wings]

Thanks for that link Bob, my mind is speeding down the fast lane with ideas. I'll post pictures as my progress begins as soon as I find a web sight to post them on.