I remember 80 millamps as one of the points the car sits at before dropping to 24 millamps when I was measuring my cars sleep mode current drain. If if doesn't drop down from 80 millamps your car has a substantial current drain, you will then have to start isolating the current drain to the engine fuse box or interior fuse box which is done by lifting the power cable to the interior fuse box at the engine fuse box.

 

So MMartinez, when you say lifting the power cable at the interior fuse box, what do you mean by that.
Yesterday, I disconnected the negative cable at the battery and hooked a jumper from the neg cable to the neg terminal at the battery. I then used an amp meter to check draw. After about 30 minutes the draw was 70 amps. I believe there will be a natural 20-25 mil draw so I am drawing about an extra 45-50 mils. At the engine fuse box I took several pictures so I could remember where each fuse goes and pulled the fuses one by one and checked the amp draw each pull. When all the fuses were out I still had a 70 mill draw. I then reinstalled all the fuses. I'm too old to get under the dash so tonight I will have the assistance of my son and we will do the same procedure for the interior fuse box.
My biggest fear is that I will pull all the interior fuses and there will still be am 70 amp draw.

 

There are two large terminals that connect to the underhood electrical center. One is from battery, the other goes to the instrument panel electrical center. Removing the terminal for the IP electrical center isolates current measurements to engine side only.








So you gave up on your DLC current measuring tool?

Just an FYI. There is a map of all fuse locations on the inside of the fusebox cover, and in your owners manual.

Why did you revert back to this? You were on a good path with the DLC tool, which freed up your meter for voltage drop measurements. You can really chase your tail pulling fuses if you do not know what you are doing.

You will need to fake out the door latch on the passenger side for this. By the way, are you absolutely certain your method with the door latch is working? How did you verify?
Pulling fuses in the IPC electrical center will definitely have you chasing your tail. Do voltage drop measurements!

 

OK, So I know I said i used an amp meter but I used a "Inductive Amp Meter" ( IAM ) around the small jumper wire to see draw. That would free up my Fluke amp meter with the probes to test fuses.

I know I must trick the computer into thinking the passenger door is closed. One way is to see if the interior lights go off. But you must move the latch 2 clicks for it to be closed as if the door was closed. And when I unlatch it the latch doesn't go back by itself so I have to open it when I am done testing.

I thought I did a good job in checking the eng comp fuse box. All doors were closed and I waited 30 minutes for the comp to run through all its diagnostics. The neg battery cable disconnected and a jumper wire connecting the neg cable and the neg batt term. I put the IAM on the small jumper wire that was connecting the neg cable and the neg on the battery. It read 70 mil when I started the test and it never changed. Since the fuse box was right next to the battery and the IAM, every time I pulled a fuse, I was able to see the IAM screen and every time there was no change. I did not reinstall the fuses until they were all out as I did not want to take a chance it would wake up the computer.

I know there is a diagram on the inside of the fuse panel lid, but I wanted to take a picture just to add another layer of security.
I will do take a picture of the interior fuse panel also. Last week, I had my son check the interior fuses with probes and a meter, but I wasn't convinced that he had the probe on the little tiny parts on the top of each fuse. It seems to me pulling the fuse is a for sure way to see the meter change or not change.
I will start by triggering the passenger door latch to fooling the computer the passenger door is closed. I will then wait 30 minutes, both cables connected to battery terminal, for the comp to run through it's diagnostics. then disconnect the negative battery cable and connect my jumper wire. Then get a base reading of amp draw with the IAM. Then have my son take a picture of the interior fuse box. Then while I am watching the IAM at the battery, he will pull one fuse at a time. When / if the amp draw changes, I will know where to look for the problem.
Again, my worst fear is there will be change, as I don't know where to go from there.

I thought the DLC could only tell me "Total" draw, not specifically where the draw is at.

 

So you have an IAM for measuring DC current?

 

Yes I do, sorry for not mentioning it before. But would it have made a difference if I used a volt meter and put one lead to the battery cable that was disconnected from the battery and the other lead to the neg of the battery? Both would have given me the same result I think.

I'm learning this as I go along. I've never had a vehicle that had a parasitic draw, and as far as I can tell a C5 is as good as any vehicle to learn on. I solicit advice from every one on the Corvette forum as I can and watch as many you tube videos as possible and through all the info eventually I will get to understand how to process all the information and be able to diagnose this electrical problem.

 

No biggie. I've always found them a bit buggy for low current DC, but if you have correlation with your other tools, I reckon you're good.

 

When I finish diagnosing the interior fuses this afternoon I will report m findings. I think I mentioned before that about 3-4 weeks ago I installed an aftermarket radio and back up camera. I certainly will feel very foolish if I find the draw is because of something I installed with the radio or camera, which is where the issue probably lies. But its a great learning curve for me and maybe I will be able to help another car enthusiast some day.

 

Did the excessive current draw issues start after you installed the aftermarket radio and camera. ?

 

Yes, but not immediately, maybe a week or so after the install.

I ran wires through the trunk, through the center counsel and into the radio. I also tapped into the rear back up lights for the power for the camera. And I drilled a new ground about 2-3 inches away from the factory ground behind the right rear taillights. The original ground bolt had snapped off about 1/4" above the chassis and I didn't think there was enough thread left for the camera negative and the factory negative.

 

Hmmm.. I think you should have led with most recent changes first.

 

OK, so I think I have found the problem. Battery fully charged. opened the passenger door and tripped the door latch to fool the comp into thinking the door was closed. Waited 30 minutes. disconnected the negative cable from the battery. Ran a jumper cable from the negative battery cable ( disconnected ) to the neg on the battery and used an inductive meter to check amp draw. 90 mils. Then my son removed the cover of the interior fuse box and it must have woken up the computer as it started reading 3-400 mil draw. Waited another 30 minutes and it went down to 110, and I had to start pulling fuses as it was starting to get dark outside. Also I suspect the comp was still winding down. So we pulled fuses one at a time as I was watching the inductive meter. When he pulled the fuse for the Right Door Control Module, it dropped an immediate 20 mil. Then I remembered at about the same time my car started draining , I had the right door panel off the adjust the window hoping it would seat better in the weather-stripping to eliminate rain water from getting in. Maybe I disrupted something and didn't realize it. We continued. And those who have coached me to start where I last messed with the wiring were correct. When he pulled the Radio fuse it went down to 16 mils. Problem identified. So now I have to take everything apart to get the new aftermarket radio out to see what I screwed up. I am also going to call Alpine to get the spec as to how much the current draw is from the radio which is needed to retain the memory of my settings. I hope it is something small.

Just to be safe I ordered a salvage yard Right Door control Module and will replace that.

 

There is no switch on the IPC electrical center fusebox cover. Removing will not trigger a "wake up" .....so that should be understood that whatever was disturbed caused that. So..........with the radio fuse removed, you have to repeat the test from square one to see the BCM go into sleep mode,.....and measure an acceptable current draw for that state. I would not change out the DCM for no reason....just another unknown variable.

 

Good idea. I will remove the radio fuse, do the door latch trick, let the computer rest for 20-30 minutes then disconnect the neg cable , hook up the jumper wire, check with my inductive tester with the Radio fuse out. I'm guessing when the comp is through with its diagnostics, it will read 19-20 mil, unless the Right Door Control Module is pulling amps.

 

I'm not following your process. There is not need to fool the door latch, as there is no reason to keep the door open. Pull the fuse, and close the door. Not sure why you would let the "computer rest" so it goes into sleep mode, then disconnect the negative battery cable, and reconnect with your wire so you start the whole process over again.

Pull the fuse. Close the door. Install your wire, or meter inline with the negative cable, and monitor the sleep mode and final current draw.

 

I will do that exactly as you have outlined and report back. I will try and get it done this evening but I have something going on and may not be able to get to it.

 

Sounds like you are on the right track.

 

Thanks Lucky, I will admit this electrical stuff is a bit daunting for me. In the old days I didn't have to wait for computers go to sleep, or trip door latches.
In 1976, I had a 1965 Corvette. The day after the purchase I realized that every time I braked, the dash lights would come on. I new nothing about electrical at that time. I get the wiring schematic and I started diagnosing on a early Saturday morning, and at 4pm I discovered the problem. I traced the wiring all the way back to the left rear tail light. Someone had installed a 1157 bulb instead of the 1156 it was suppose to have and it was feeding back to the dash lights. Changed out the bulb, problem solved. But back in those days the wiring was laid out so it was easy to understand.
So I'm still muddling through this stuff, but instead of getting aggravated about it all, I see it as an opportunity to learn more stuff about my C5 which I love to do. And believe me I've had plenty of opportunities to get aggravated at my car.

 

 

ok, More testing last night. Remove the Right Door Control Module fuse and the Radio fuse. Jump wire connected between the negative cable and the negative post on the battery, put on my indictive tester around the jumper wire and watched the computer run through its process. After that the lowest draw was 54mil. Not the 19mil I had yesterday. Then I installed the fuses and did the same thing and the lowest draw was 75mil. So to me I was not able to replicate the same results as the day before.
I have ordered a Right Door Lock Module ( from a Corvette salvage yard ) and it should be here in a day or two. Just for peace of mind I will change this out and eliminate any chance of this being a potential problem. Then do the testing all over again.
Also, I checked battery voltage and it read 12.97 v. Right at the 13v I was hoping to get.
Lucky, am I on the right track?