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Hi All, I need to some advice on what to try next. So I had a 1.5A battery drain in the CLK LTR CTSV circuit (current goes to 0A when I pull out the fuse so I know the issue is on this circuit). Here's what I did:
Removed all 3 courtesy lights and no change in current draw.
I then took apart the parking brake trim, unplugged cigarette lighter and no change in current draw.
I removed the aftermarket splice from the cigarette lighter P.O. put in (so now the orange wire coming from wiring harness and has nothing else attached) and current draw went down to 0.45A
So I thought rest had to come from clock. I disconnected the clock and it still has a 0.45A current draw!
I unplugged the two black wires from the switch behind the seats, and still no change in current.
Where else could it be coming from? I have the 73 wiring diagram, but I think I covered all the places it could be coming from? Any pointers of what else I can try would be greatly appreciated.
The rear compartment light and factory alarm are also on that circuit. Check both of those and report back.
Cheers, Greg
I saw those on the circuit diagram but wasn't sure if they were part of the circuit. I think they are just attached by a separate connector, but like you mention still on the circuit. I should be able to check that later tonight and report back, thanks for the tip!
The alarm circuit is definitely on the same circuit as the courtesy lights, thanks Greg for pointing that out. This was my first time reading automotive wiring diagrams so I overlooked the connector wiring.
I checked the factory alarm circuit and here's what I did:
Unplugged the anti-theft relay located in jack compartment. No change in current draw. This means the issue is on the right half of the circuit (see 1st image below from 77 electrical troubleshooting manual)
I left the relay unplugged and unplugged the flasher, and still no change in current draw (~0.45A).
Does this mean my horn is getting grounded somehow and is constantly on? That's my understanding of the wiring diagram i posted in image 1 below.
I couldn't find any sort of light in the rear compartment, I think the P.O. removed the entire light housing.
I'm thinking for next steps to unplug the horn (I heard it's a PITA to get to, deep up under the rear fender on driver's side). I have the 3 courtesy lights, clock, cigarette lighter, anti-theft relay, and anti-theft flasher all unplugged. So I think it has to be the horn? 1. 77 wiring diagram (I believe 73 is same)
2. jack compartment after i unplugged the anti-theft relay and flasher. There is some speaker wire from P.O. that I need to unplug.
3. Not sure why the orange wire is hooked up to black wire here, I think this means that when switch is pressed I might be getting a short circuit? In either case I unplugged it and no difference in current draw.
Last edited by roamin' around; Sep 21, 2021 at 03:47 AM.
Hmmm?
A couple of things here. First, use the correct year schematic as the '77 is slightly different. Here is the rear part of the diagram with correct color coded wires for 1973. I'll post it large enough so you can download and zoom in.
Second, if you've pulled the alarm flasher, you can see by this diagram that this should eliminate your horn as the possible issue.
Third, this is the rear compartment light. It should have a corresponding white lens in the center compartment insert for the bulb to shine through. The plunger is in the HOT position as shown in your picture. It would be OFF when the plunger is pressed down by the compartment lid but, as there is currently no bulb in the socket and the ground side is unplugged, this will not be a draw.
You'll also notice on my schematic a "Battery Compartment Light" on the same circuit. This is superfluous as I don't think any '73's went to production with this particular light.
You mentioned earlier that a previous owner had tapped into the cig lighter circuit for power. I have seen that many times as well. Does the car have any after market stereo equipment, amps or other accessories that have been added? Generally draws are due to exactly this type of thing.
Greg
If you do find the rear storage compartment is the culprit, park your car in the garage (no lights), or at night look inside car with doors closed (windows down), you should see light around the closed lid if its on. On my 73 you have to push down pretty hard to engage the lock and to get the light off. I have seen the light stay on when I wasn’t careful about pushing down on the lid. Another reason I changed all the bulbs to LEDs, very little heat and low current draw.
Hmmm?
A couple of things here. First, use the correct year schematic as the '77 is slightly different. Here is the rear part of the diagram with correct color coded wires for 1973. I'll post it large enough so you can download and zoom in.
Second, if you've pulled the alarm flasher, you can see by this diagram that this should eliminate your horn as the possible issue.
Third, this is the rear compartment light. It should have a corresponding white lens in the center compartment insert for the bulb to shine through. The plunger is in the HOT position as shown in your picture. It would be OFF when the plunger is pressed down by the compartment lid but, as there is currently no bulb in the socket and the ground side is unplugged, this will not be a draw.
You'll also notice on my schematic a "Battery Compartment Light" on the same circuit. This is superfluous as I don't think any '73's went to production with this particular light.
This colored diagram is helpful. So the horn would only be the issue if it is somehow getting grounded (which it shouldn't be according to the diagram). So it seems like this is a low probability. I'll try to unplug it anyways if I can easily reach it (I already have the spare tire carrier out so maybe it will be easier to reach).
I think I now understand how the bulb is wired, thanks for that. So the orange and black wire should be connected as shown in the picture, and the other black wire connects to another black wire (which isn't pictured). Also it grounds when the switch is pressed, I messed that up in my original post thanks for pointing that out.
You mentioned earlier that a previous owner had tapped into the cig lighter circuit for power. I have seen that many times as well. Does the car have any after market stereo equipment, amps or other accessories that have been added? Generally draws are due to exactly this type of thing.
Greg
Originally Posted by Eliredandblack
If you do find the rear storage compartment is the culprit, park your car in the garage (no lights), or at night look inside car with doors closed (windows down), you should see light around the closed lid if its on. On my 73 you have to push down pretty hard to engage the lock and to get the light off. I have seen the light stay on when I wasn’t careful about pushing down on the lid. Another reason I changed all the bulbs to LEDs, very little heat and low current draw.
I believe my car did have some aftermarket stereo equipment at some point, but all of that has since been removed and only the wiring is left. I had another thread recently about the non-factory wiring I found in the cigarette lighter area, and have since removed all the wires from the cigarette lighter. Previously my current draw was ~1.5A, and after removing the non-factory splice from my cigarette lighter, I was left with the current drain of ~0.45A. My post for those interested is here: https://www.corvetteforum.com/forums...questions.html
Eliredandblack was helping me over there.
All of this being said, I do have a key fob which I need to press before starting the car (installed by P.O.). I think it's RFID kind, but not sure where the receiver is for that. All I know is that when I unplug the courtesy light fuse, my current draw goes to 0A. Is there any place on the courtesy light circuit that's always hot where it's easy to splice stuff from (that isn't the cigarette lighter)?
I just removed the rear compartment light holder, there was no light in it but is was super corroded as you can see below. As Greg mentioned, it wasn't connected to GND so no difference in current draw. Huge build up of material in the rear compartment light holder.
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73 Courtesy Light Circuit Help
