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My battery has been draining for a few days, even after recharging. Before this started I have had a Battery Tender Jr. on it and usually keep it on it when in the garage. The battery is only about 2 months old (Interstate). What caused me to start this test is that the battery tender was not going to green light, so I removed it and one morning the battery was dead. I then charged it, but overnight it drained and was dead. While charging, it would start at 8 amps but never went below 4 amps. Today I had it fully charged and started the test. After checking the hood fuses it dropped from 12.65 to 12.35 by the time I found the three parasitic fuses,
Doing a fuse check today after studying up on it for a couple of days, I found nothing in the under hood fuse box but found three fuses drawing voltage in the passenger fuse box. From here I don't know what the fuses are for or where to go from here.
Fuse #20 - a 10amp fuse labeled CR Cont - drawing 10.1 millivolts (1348 mA or 1.348 amps)
Fuse #30 - a 10amp fuse labeled DCM-R - drawing .8 millivolts (108mA or .108 amps)
Fuse # 33 - a 10amp fuse labeled DCM-L - drawing 1.8 millivolts (243 mA or .243 amps)
What are these fuses connected to?
Is this enough to drain a battery overnight? if no, what else should I check
Re:2002 vert, 87.5K miles
Last edited by WetMountainMan; Jul 16, 2018 at 11:19 AM.
Reason: sp
Fuse #20 drawing 1.3 amps could definitely kill a battery overnight...........
Did you do the current draw test with the key off and out of the ignition??? Doing it with the key in the ON position is NOT a valid current draw test since there are MANY electrical circuits in the C5 that draw power when the key is ON.........
Thanks for the info!
I put the car to sleep, flipped the door locks and hit the fob lock also. no key in the ignition, all lights off, nothing showing to be on.
With the three fuses out, It shows to have no draw on the battery, but it is still dropping voltage - down to about 12.20V now. But I put the charger back on in case I need to do more testing later.
My cruise switch bar was in the on position but I turned it off after the test, thinking the CR Cont might be the cruise. Now that I know the #20 is the cruise, I will put that fuse back in and retest the draw - with the switch off. If it does not show a draw, I guess that was the problem and I will have to remember to turn it off before shutting down. If not, I'm not sure what to do about it.
Are the DCM draws in an acceptable area, or should they be zero? What can be done to reduce them?
I've no problems with any of this until last week after taking a 160+ mile drive (when I noticed that the battery tender was not doing anything).- nothing has changed.
Last edited by WetMountainMan; Jun 26, 2018 at 05:11 PM.
Right after I bought my 03 vert almost a year ago I had some work done to it. It was in the shop for 3 days. When I got it back I cleaned it up inside and out. The next morning I get in it and the battery was dead.
I go buy a brand new Interstate and put it in. I put my trickle charger on it for overnight. The next morning the battery is dead after charging all night.
The dang brand new Interstate battery had a bad cell!
Check the new Interstate battery.
Last edited by Grandpa1; Jun 26, 2018 at 05:34 PM.
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
the alternator bad diodes will allow the vehicle to charge normally and then drain the battery....an auto parts store can test this for you while the alternator is in the car for free, its a pretty painless test and gives you good information.
I give up, tried everything, even brought in a friend who is very car & electrical savvy and we cannot find the 3.35 amp draw. We either checked or pulled (or both) every fuse, circuit breaker and relay in the car and checked the alternator. We did find that the battery and alternator are OK.
Anyway, I made an appointment with a Chevy dealer to check it next Tuesday.
3 days of this and I'm just burned out. I hate electrical crap.
1 amp parasitic drain troubleshooting, new battery!
Originally Posted by 8VETTE7
Don't know if you have previously reat this little excerpt from a Bill Curlee, Forums resident electrical wizard, about common current drains in the C5 or not: The correct BCM current draw should be 30 Milliamps or less. Most C5 run around 25mabut I have see some as low as 15 ma.
Leave the engine compartment fuse box for last and start with the passengers compartmentbox first. Pull the power seat breakers FIRST! The power seats have a tendancy stay onand cause this issue.
Also pull the fuses for the Bose system amp.
Examine the car in the dark for lights staying ON.
Once you prove the interior circuits good,,, check the headlight circuits, and then testthe current draw of the alternator.
Look at my electrical stickey. I think I cover this in detail in that post.
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
Also since you sound like you are new to current drain testing procedures, here is a link that Bill Curlee put together some years back that may be of help: http://forums.corvetteforum.com/1567522286-post590.html
- Sunday 7/15 and this post is so helpful - dead battery recently, it was old I just assumed bad and replaced it, dead again next day, 100K mile 03' 50th Anniversary model. Had the new battery tested and they did other diags too (thank you, Advance Auto Parts, Golden CO who are awesome) and found a 1 amp drain on it.
I'm doing as above, and need to read that other post. I jumped the car, ran it awhile, off, showed 12:16a amps across battery terminals and began dropping slowlyl/steadily.
In the passenger fuse box, I removed the 3 fuses - lumbar, Bose and ?
In about 45 minutes it only dropped from 12:12a when I pulled those fuses to 11:75a, does that sound like good (its one of those fused circuits I pulled) or, not?
Or do I need a full deep charge to even be doing testing?
THANKS I will read up more on this but any feedback appreciated, great posts!
It was at
First I hope that you were using the volt meter function if you are reading across the battery posts. Current (amps) is measured with the meter in series to the negative battery cable and negative battery post and with the meter properly configured to measure amps.
If you were measuring voltage and the meter was set up to measure volts then the fact that the battery voltage continues to drop is a strong indication that you have NOT YET found the fuse that is the cause.
I would suggest that you start with a fully charged battery before doing any further testing. A good battery at full charge will measure 12.7 to 12.9 volt or more when measured across the battery posts with the neg battery cable disconnected.
If
Yes, sorry! Volts, duh. OK those 3 fuses out still allowed a drain, I've jumped it again, idling and I have removed the two big power seat breakers from the passng fuse box, I'll turn if off in a bit and see what that does, then maybe try some others that are not necessary to operation. I know guys have written they found a short in the door to frame wiring, it could be anywhere.
THANKS, I appreciate your knowledge!
My problem has been fixed. I took the car to Daniels Long Chevrolet in Colorado Springs and Mark, the electrical guru there, fixed it in a few minutes. The problem was that the dash light dimmer switch was all the way to the right (clockwise) past a detent (click) and that opens a circuit that the BCM reads as open doors, interior lights on, and cruise control on (plus possible other items) and draws current from the battery even though those items were not on..
I had turned the dash lights up at some point and went all the way right for brightest like the manual says (in two places). What the manual does not say is to NOT turn it to the detent/click - at full clockwise. After Mark turned the dimmer switch back, the amps began to drop. After it settled out, the meter was showing 25mA as is usual.
I don't know if others on here have had that problem or even knows about that switch's far right position problem, but Mark said he has seen it many times,
BTW - Mark, the tech, had a 1995 C5 two bays down from my car that has been there about a week with terrible electrical problems. The car has a brand new battery, BCM, and ECM and he has traced everything in the car he knows and has not found the fix. He has even had factory help and still no luck.
I felt lucky!!!
Last edited by WetMountainMan; Jul 15, 2018 at 03:26 PM.
My problem has been fixed. I took the car to Daniels Long Chevrolet in Colorado Springs and Mark, the electrical guru there, fixed it in a few minutes. The problem was that the dash light dimmer switch was all the way to the right (clockwise) past a detent (click) and that opens a circuit that the BCM reads as open doors, interior lights on, and cruise control on (plus possible other items) and draws current from the battery even though those items were not on..
I had turned the dash lights up at some point and went all the way right for brightest like the manual says (in two places). What the manual does not say is to NOT turn it to the detent/click - at full clockwise. After Mark turned the dimmer switch back, the amps began to drop. After it settled out, the meter was showing 25mA as is usual.
I don't know if others on here have had that problem or even knows about that switch's far right position problem, but Mark said he has seen it many times,
BTW - Mark, the tech, had a 1995 C5 two bays down from my car that has been there about a week with terrible electrical problems. The car has a brand new battery, BCM, and ECM and he has traced everything in the car he knows and has not found the fix. He has even had factory help and still no luck.
I felt lucky!!!
THIS was my problem too! Or I'm pretty sure because I just went out and indeed, the **** was turned past the detente to full stop, I remember messing around with it, probably the day before the battery died. I was getting a new HUD windshield the next morning and was just fooling around with the brightness to compare to the new windshield (from Safelite, great job, HUD looks fine, $100 insurance deductible but cost with a new liner was about $1400). So I'm jumping it (it's totally dead) and once I get at least a decent surface starting charge, I'll see if I still have the 'drop'.
I owe you big time!
That dash/HUD dimmer switch being full right was the problem, 20 minutes now and still about 12.14v - previously it would drop like a stone within minutes.
Unbelievably bad design, WTF??? WetMountainMan, I owe ya. You should make sure this tip gets into the electrical troubleshooting at the top of the list. This current post has the typo or 'parasiic' instead of parasitic draw.
THANKS ALL, buy ya lunch and beers if you're ever in Denver!
Well I'm pretty certain that leaving the interior lights on overnight and during the daytime is a mistake that neither of you will make again.
But the list of things to check that I provided definitely addresses "INTERIOR LIGHT ON (CHECK IN THE DARK)"
I did everything on your list and several others, and watched what was shown on several videos... and the interior lights werenever on, The car was: "asleep".
That dimmer switch at full right made an open circuit to the BCM. After every battery charge, I looked at the floor lights, in the dark (and they are very bright LEDs) - they were NEVER on.
Last edited by WetMountainMan; Jul 16, 2018 at 08:19 PM.
That dash/HUD dimmer switch being full right was the problem, 20 minutes now and still about 12.14v - previously it would drop like a stone within minutes.
Unbelievably bad design, WTF??? WetMountainMan, I owe ya. You should make sure this tip gets into the electrical troubleshooting at the top of the list. This current post has the typo or 'parasiic' instead of parasitic draw.
THANKS ALL, buy ya lunch and beers if you're ever in Denver!
Glad that helped you, and I agree that it's a bad design.
I appreciate the offer, but I try to stay out of Denver traffic! LOL
BTW - I changed the spelling.
Last edited by WetMountainMan; Jul 16, 2018 at 08:18 PM.
I will play with that in the dark now that I have power again but glad to hear that dimmer is in your checklist, thanks! I only worked on it in daylight and it was always dead by nightfall so, no indication the lights were on, kind of a Catch 22.
Just adding my experience to this thread in the event it may help others.
Had a horrible drain issue... killed 3 batteries to the point of no return. While doing Bill Curlee's drain test, I found my horn relay warm and the 20a fuse for the horn was blown. I realized then that I had never tested or used the horn during my ownership. I tested the relay terminals and had voltage to all 4 contacts (should only have on 2 unless you're pressing the horn). Pulled the airbag off and tested the red and black horn wires and had continuity (should be open or OL unless your pressing it). Swapped out the horn membrane and I'm GTG now.
now I can work on my targa roof leaks...should've bought an FRC....
My problem has been fixed. I took the car to Daniels Long Chevrolet in Colorado Springs and Mark, the electrical guru there, fixed it in a few minutes. The problem was that the dash light dimmer switch was all the way to the right (clockwise) past a detent (click) and that opens a circuit that the BCM reads as open doors, interior lights on, and cruise control on (plus possible other items) and draws current from the battery even though those items were not on..
I had turned the dash lights up at some point and went all the way right for brightest like the manual says (in two places). What the manual does not say is to NOT turn it to the detent/click - at full clockwise. After Mark turned the dimmer switch back, the amps began to drop. After it settled out, the meter was showing 25mA as is usual.
I don't know if others on here have had that problem or even knows about that switch's far right position problem, but Mark said he has seen it many times,
BTW - Mark, the tech, had a 1995 C5 two bays down from my car that has been there about a week with terrible electrical problems. The car has a brand new battery, BCM, and ECM and he has traced everything in the car he knows and has not found the fix. He has even had factory help and still no luck.
I felt lucky!!!
just wanted to thank you for this post. Noticed my battery draining way too quickly after full charge on tender and indeed my dash light dimmer was all the way to the right past detent. Hoping this fixes my issues.
Help - parasitic draw
