Hello fellow owners and enthusiasts,
(1997 C-5 )
I recently have come upon the dreaded DEAD BATTERY problem. My car ran fine all summer and into the fall. Well after letting it sit a week I had a dead batt. So I followed the advice on here for charging, and my car worked fine for around 2 weeks. Well here I am, again.
I found the threads on here for running the Multimeter tests and they were wonderful, the pictures were very helpful. (Thank You Bill Curlee)
Now here is my question.
I set the multi meter on the 10AMP DC test (the yellow selection on my meter) and I get a reading of like 2.14 sometimes 1.9 with various fuse pulls and such. (Mr Curlee's is on AMPS I think)

Then I switch the meter to the milliamp (blue on my meter) and I get .014

AM I supposed to keep the wires hooked up for 3 minutes or so to ensure the Vette goes to sleep?

Which reading am I supposed to go by? In the threads I see various answers but am still a little confused. Any suggestions?

 

You should see a reading of about 20 ma after the car has gone into the rest mode, about two minutes. Make sure that the doors are closed and the hood light is off.

 

The meter should be in the DC AMP Mode. When you first hook up the amp meter, the BCM and PCM will cause the system to draw about 8 amps and as the systems shutdown, the current will drop down in steps (it is slightly different in each model C5) 8,,,3,,,,,,,1,,,,,,,,.02.

Make sure that all the systems are off (ie doors shut, hood light disconnected, trunk shut, radar detector off ect...........)

This is the reading I got after the BCM turned everything off and entered the sleep or monitor mode:



If something in the RAP circuit is on,,,,it can take about 10 min for the car to go into monitor mode

Hope this helps.

BC

 

I believe it takes longer than 2 minutes for everything to go down to the low current draw level. If I recall correctly, my Zee took about 10~15 minutes to see the current draw go down to 18 mA.

 

If you are seeing 0.014 A then that is the same as 14 mA. A normal draw with the car sleeping should be 20 mA or less.

 

Thanks for the replies everyone, Here's what I got so far...
Mr. Curlee, it IS the AMPS reading and not the milliAMPS reading. OK

After closing the doors and pulling the hood light wire here is what I got...
I left the meter hooked up in 10 AMP Mode, my reading was 0.84 and remained that as I pulled various fuses under the hood (I waited about 5 minutes before pulling stuff). Nothing changed.
I did pull the wires off of the "under hood" fuse box and the reading dropped to near nothing. Put the wire back and the reading went back to .84 AMPS .
1 note, the reading changed if the meter probe moved in the wrapped copper wire.
The day came to an end.
SO tomorrow I will re-do this again (weather pending) and this time I will leave the meter hooked up for 15 minutes before trying anything.
I will take a picture of what I am doing if it helps to ensure it is right.

Once again, thanks everybody for your assistance.

 

First off,,,,,its BILL

Next, if you let the car sit for 15 min, and the reading has NOT dropped, thats what it going to be. If your reading above 30 ma, it is way too high! You really need to examine what fuses/relays your pulling. If you pull a BCM relay/fuse,, you could cause the system tp wake up and skew the readings.

If the car is in (Retained Accessory Power) RAP mode, it's applying power to all the aux circuits (radio, windows, ect.. and the reading will be high. The RAP Mode will terminate after 10-12 min.

An easy way to tell if the RAP mode is off, roll the window down, shut the door, enter the car from the open window, turn the ignition ON and then off. If the radio is ON, it will play during the RAP mode. Once the RAP times out, the radio will shut off and the car will be in sleep mode with in 3-8 min.

If the reading is HIGHm start removing fuses for stuff like power seats, headlights, Bose system, lighting cirsuits, ect....

BC

 

SO today it was finally nice outside.
I performed the last test. I opened all the windows and turned the radio on to ensure the RAP mode shut down.

The reading dropped to .098 and .08? for a short time then
It held steady at .029 for quite sometime, it would tap .030 for a blink.

I pulled the wire off of the meter then placed it back on, it hung out in the .03's for a short then once again held steady at .029

I see your meter does not have the thousandths position so maybe i am good at the .029 reading.

The only thing left is to leave the battery hooked up again overnight and see if is dead come morning.

 

Those are good BCM sleep readings and if you have a good battery thats FULLY charged, the car chould be able to sit for a MONTH without an issue!

The ONLY other thing that might cause this is a switch or relay that sticks every now and then. A good one that will do this is the multifunction switch on the drivers or passengers seat! The LUMBAR switches will also do this. Make sure that they have GOOD spring tension to the center position.

BC

BC

 

Not to leave this thread fully unanswered...

I never quite found the battery drain gremlin. I assumed it may have been the seat motors so I unplugged them. The battery has not drained since my last post. So maybe it was the seats...

So I am good for now.

Thank You Bill Curlee and anyone that offered any insight to this issue.

 

Not to highjack this thread but my problem, which I haven't seen posted here on the forums, is when detailing my car and I have the hatch or either door open for any length of time, maybe over an hour; when I try starting the vette I don't have enough juice to start her. The only things that appear to be turned on are the interior courtesy lamps. What could possibly be draining my battery so quickly, the courtesy lights? The battery, a Diehard, is the same one I've had for the past two years and it starts the car up daily with no problems, except when detailing my car.

 

I had my hood up today working on my oil pressure sensor and mine died. I guess that hood light killed mine??

 

I usually have my hood open too when detailing my car. Do I need to get a hood light switch?

 

is a .08 reading good with my meter in the 20A mode??????thanks Ray

 

your hood light should turn off after 10-15min. along with the other lights. now if you keep opening and closing doors and and what not, then you will activate that 10-15min period again. you shouldn;t need a hood light switch. ive detailed my car plenty of times. times when its been been like2 days of detailing and have never had a dead battery with leaving doors open and opening and closing etc.

 

A sign that a battery is going bad is that it will NOT support aux loads for A short period of time, like the radio when you waiting for some one at the store, under hood light while you have the hood open during a car show, or a radar detector left on over the weekend.

If I were you I would remove the battery and have it tested. Make sure that they load test it. Under a load test, it should be able to support a high current load and the battery voltage should not drop down below a specific amount. (Like 11.5 VDC)
Once the load is removed, the steady state at rest voltage should return back to 12 VDC.

Battery current draw is inversely proportional to battery voltage output. If you take a lot of current out of a battery (like starting the engine with 250-300 amps) the voltage will try to go as low as the battery is able to supply. If you have a battery that has plates that are sulfated or shorted, the battery can only supply a small amount of voltage compared to the output current.

I bet if you put a volt meter across the battery terminals and cold start the engine, you will see battery output voltage dive down toward 9 VDC for a very short period of time.

Another very good indicator of battery trouble is if you see a LOT of history U series DTCs in the LDCM, RDCM, RFA Module, HVAC module and RADIO. That means that the module was NOT happy with the voltage and shut down until the voltage returned to a level above the module LOW VOLTAGE cutoff threshold.



rraulston If your in the 20 AMP scale,,,.08 would be 80 milliamps. .02 would be 20 milliamps. Always use the scale that is close to the max reading that you expected to read. You can start out in the 20 amp scale and then switch to the 10 amp scale If you had a 1 amp scale, that would show you the best resolution. (like 0.020)

BC

 

NO! You should see a reading like .02.

BC

 

sorry to bring an old thread back but my reading is at 1.02 and when i take out the radio fuse it drops but the battery still dies in about a full day with the radio fuse out so i don't think is the bose radio,i'm thinking it could be the bcm but guessing can get expensive,i've had this dreaded problem for over a year so needless to say my charger works a lot,this is frustrating because it takes the fun out of the car and i sure as hell don't want to sell it.

 

What does it drop down to when the radio fuse is removed? The most common things that cause excessive current draw are the seat control module always being on cause the seat position switch or the lumbar switch sticks ON.

The headlight control module under the passengers headlight. Feel it. If its warm, its causing draw. When the lights are off, there should not be any current draw in that module.


The Bose amp (you have already experienced that one) because the relay sticks on.

Examine your car in the dark and see if a light somewhere is always on.

The alternator could have a bad diode and always be drawing current. Remove the large red wire on the back and hook the amp meter up between the wire and the terminal to see if there is current draw. There shouldn't be any.

Do you see the BCM powering down when all the lodes are off?

BC