New to this forum. I'm sure the 03 battery drain has been discussed before but I couldn't rewlly find the answer I'm looking for. I have an 03 z71 tahoe. A few months ago it started killing batterys overnight. This is intermittent. Sometimes it does somtimes it doesn't. I have replaced 2 battery now. I have recently fixed the engine block ground, put in a new BCM. the battery is charged by the alternator just fine. Everything appears to shut off after vehicle is turned off and door is shut. I have tried to do a parasitic drain test and all I see is 12-14 mili amps. I'm not sure how to diganose this issue.
2003 Z71 Tahoe intermittent battery drain
- Thread starter Hutch123
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
HiHoeSilver
Away!
One thing you can try is to pull fuses one by one while your meter is on the battery and see if any particular fuse has a noticeable effect.
M1Gunner
Full Access Member
There’s quit a few different scenarios our older trucks will drain the battery for... intermittently. 1. BCM starting to fail... 2. Drivers door latch starting to fail... 3. Vanity mirrors switch with powered lights in the sun visors failing... 4. Aftermarket installs... ^^^ as silver stated catch it in the act and start pulling fuses.
swathdiver
Full Access Member
William, do you have access to a Tech2 or a scan tool that can pull internal body module codes? The BCM does look for and has codes for parasitic drains. Any work done on your ignition lately? If the ignition lock is not installed right, such can drain the battery too.
No aftermarket parts and no recent ignition work that I know of. Bought used 3 months ago. New development though. Tonight it went into reduced power mode again which it hasnt done since the new BCM. Also, used my brights tonight for the first time in awhile and the instrument panel lit up like a chrismas tree. Speed and tach shut off and all the scary lights came on. Car even jolted. and then everything went back to normal. Does this almost every time I hit the brights. Related?
Last edited:
swathdiver
Full Access Member
Well, where do you live? Maybe someone nearby has a Tech2 and can lend a hand?
Charleston SC. I'm wondering if my battery cables could be the issue. I just went into a convient store and came back out and the car was completely dead after I just drove over 200 miles!! I thought no way. I wiggled the side mount terminals and nothing changed. I wiggled the battery cables on accident and I heard my open door alarm. Truck started right back up....any thoughts?
HiHoeSilver
Away!
Change em and see.
swathdiver
Full Access Member
Check them for tightness and corrosion and even if you cannot see it, you'll probably be best off replacing them. I've done battery cables on most of the GM cars we've owned since the 1980s.
bladenbullet
Member
- Joined
- Feb 3, 2015
- Posts
- 35
- Reaction score
- 19
you may not need to replace them....I had a cable causing a dead vehicle 2 years ago and repaired it by re-crimping the ends and sweating them with solder...a simple voltage drop test can identify whether a cable is faulty...
with a dmm set to volts place one probe on the battery terminal (under the cable end) and the other on the other end of the cable...with the fuel pump disabled crank the engine and watch the voltage....it should remain below .1 volts...honestely it should be in the low hundredths of a volt...any reading above that indicates you are losing voltage through a bad connection...
these vehicles are notorious for cable ends losing contact with the cable itself...the result is a dead vehicle after trying to crank...
in the event the cable is dropping voltage, use a propane torch to heat the end...drop some soldering paste in the joint and sweat some solder into it...it is a permanent repair...mine was dropping 1.5 volts when I tested it...the vehicle would go completely dead intermittently when trying to crank about once every 1-2 weeks....it has been over 2 years since the fix and no problems at all...
with a dmm set to volts place one probe on the battery terminal (under the cable end) and the other on the other end of the cable...with the fuel pump disabled crank the engine and watch the voltage....it should remain below .1 volts...honestely it should be in the low hundredths of a volt...any reading above that indicates you are losing voltage through a bad connection...
these vehicles are notorious for cable ends losing contact with the cable itself...the result is a dead vehicle after trying to crank...
in the event the cable is dropping voltage, use a propane torch to heat the end...drop some soldering paste in the joint and sweat some solder into it...it is a permanent repair...mine was dropping 1.5 volts when I tested it...the vehicle would go completely dead intermittently when trying to crank about once every 1-2 weeks....it has been over 2 years since the fix and no problems at all...
Similar threads
