Lamp monitor panel shows stop light staying on and draining battery

Hi,

As temporary fix, please unplug the battery from the car when you're leaving it for more than 15 minutes. This should stop it from being drained by your parking lights.

Thank you.

I believe the glove box light stay on or the trunk light , all the best.

Do you know anything about automotive electronic's ? The brake pedal position sensor is a input to the BCM - body control module ,the BCM turns on the stop lamps . Possible short in the (CHMSL ) - center high mount stop lamps , wiring etc.... Causing problem inside the BCM . Do you know what wiring diagrams are ? Free one's here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine size . Under system click on lighting , then under subsystem click on exterior lighting . Click the search button then the blue link's . First diagram show's the brake pedal position sensor input to the BCM ,lower right . Second diagram show's BCM power supply to the third brake light (CHMSL) . Having a qualified repair shop with a professional scan tool to check for DTC'S - diagnostic trouble code's could save a bunch of time in diagnosing the problem .
DTC B3903
The body control module (BCM) supplies voltage to the center high mount stop lamp (CHMSL) and the powertrain control module (PCM) when the stop lamps are active.
DTC B3903 Stop Lamp Relay Circuit

Stop Lamps
The body control module (BCM) is responsible for controlling the stop lamps. When the driver presses the brake pedal, the BCM will receive a signal from the brake pedal position sensor. The BCM then supplies battery positive voltage to both left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The stop lamps are grounded at G401 and G403. The CHMSL is grounded at G302.

Boot lamp, interior light, radio, I've also seen the brake lamp switch stick on brake lights will stay on then...
Go through and check all the above items..

say what lights exactly , the cab of cars can have 20 freakn lights.
stop guessing, please, and huge costs an labor, !!

you car has what is called dark current.
you saw the light fai,l in the dark, and ignored that.
that IS The problem , it flattened the battery , that is NORMAL.
Normal for and illegal DRAIN.

ok, I see lamps on, key off. HL switch off. Head Lights (HL)
so , i pull fuses 1 by one, and bingo X fuse kills the lamp(s).
i trace that fuse path only ,using my ammeter.

here is a phantom drain page.
shows 3 ways to trace it, best is an ammeter.

http://www.fixkick.com/drain/drain.html


think of a car electrics as a tree.
and one branch as a problem?. the fuse protects each branch
from catching fire. and allows you to measure the current on each branch very easy.;
we use the ammeter to find which twig is shorted (switch closed in error or , a real short, of random happenstance_)
is this better/
good luck to you and do ask any questions. (how to, on all)

To hyjacker Jeeda
and others.

Yes, all cars can do this, we call it KEY OFF phantom drain.

most cars spec list ILLEGALL drains (spec)_ as over 0.050 amperes. (50mA max)KeyOFF.

Here is a short to do list to find it. (most steps need ammeter to find it, )
1 A dark garage. find lamps stuck on, every INCH of car inside and out. go slow and look (bingo?)
2: connect the ammeter to the battery PLUS lug. see that drain? illegall? now, key off for sure.
3: now unplug every fuse 1 by 1 to find the feed that has drain. (cab/ eng.bay) unplug and put back. actions.
4: unplug all relays, same way as fuse, found it, yet? see drain go away is he goal, simple goal.
5: ok 3 or 4 finds bad feed line with drain,we then unplug all things 1 by 1 on that failing feed found above.
6: ok nothing found yet,(cause) move ammeter to huge wire on the Alternator, lub, see a drain there (BINGO bad ALT)
the below ammeter (amp/clamp) is the most easy way to find Phantom Drains. bar none

unless the scan tool scans told you what was bad ?
a Phantom drain allowed to persist can wreck the battery in just 24hours.
THE METER must DO DC amps (many do not and costs tad more for DC amps) DC CURRENT
AND A 2AMP RANGE. at least.



https://www.amazon.com/Current-Auto-Ranging-Digital-Ammeter-V-Alert/dp/B094R8CB4W/ref=sr_1_10?keywords=dc%2Bamp%2Bmeter&qid=1659787362&sr=8-10&th=1

on my meter it has autozero button that must be pushed 1 time in current mode. to calibrate it first ,and clamp; the wire first. (better meters cost more)
I put a STAR icon to show the amp lamp test points, (battery cable and ALT) simple example.

I highly doubt that the clock radio is drainng your battery. Check the under hood lamp, the glove box lamp, and if none of these lead you to the cause, the put a 12 volt test lamp between the battery neg, terminal( having removed it first) and the battery neg connector. If there is a draw, the lamp will light brightly. Remove fuses untill it goes very dim, and that will be the circuit that has the draw. Should be easy to narrow down after that! Good luck, and let me know what you find!

Hi Dennis,

Your courtesy lights are controlled by your Body Control Module (BCM). Normal operation is for the courtesy lights to stay on for 2-3 minutes after the door is closed, then turn off.If they stay on longer than about 3 minutes, then there are several possible causes:

1. You may have the "courtesy lamp override switch" in the overide position in the dimmer control on the dash.

2. you may have a door that is not completely closed. You need to check ALL of them.

3. You could have a defective door switch or dimmer control switch

4. you could have a short to ground in one of the door control switch circuits, causing the BCM to "think" that there is a door open.

The CORRECT way to fix this would be to scan your BCM for fault codes and also read the BCM data to find out if it is showing one of the doors as being open when they clearly are not, so you will know which door is causing the problem.

Removing the courtesy lamp fuse will NOT completely fix the battery drain problem if these circuits are shorted or malfunctioning because the BCM will STILL be "trying" to turn these lights on and this will also cause an excessive draw on your battery. However, removing the 15 Amp fuse marked "CTSY LMP/MIRROR" located in the instrument panel fuse block will get the lights turned off and at least slow down how fast your battery is draining.

Hi, CSTY is abbrevation for courtesy lamps. They can be interrior lamps in the dome, footwell, inside headspace front and rear, map lights, glove box , door jams/panels , under hood and trunk. First verify that all your lights are going off when the doors are closed and key is off. For trunk and under hood courtesy light, use the push switch to verify they do turn off. (I've had a few under hood lights short out and do that) Next would be to remove bulbs one at a time and monitor your battery. (Painstaking, but effective) other than that, you have a short somewhere, lights in the bottom corners of the doors can get moisture and usually corrode first. Good Luck! Mike

Disconnect one battery terminal (+ or -) but not both and place a large lamp like a headlamp (12v) in series with the battery terminal that is disconnected and the terminal that you removed. If the lamp lights, you are getting a phantom power drain. If the lamp lights dim, place a smaller lamp like a signal light; 5 or 10 watts or so. If you have an ammeter, use that instead as long as you can read it from the fuse area as you go through this process.

Go to the fuse panel and in order, remove the fuses one by one. When you remove a fuse, and the lamp stays lit, put the same fuse right back. Keep going through all the fuses until you find one that shuts the test light off. When you find the fuse that causes the problem, the circuit that is fed off that fuse is causing the problem. I had same issue and no circuit raised its head.

It is normal for the car to draw about 20 to 50mA which keeps the clock and other presets alive and allows the body computer to accept signals from the remote door lock. This is very little current for a car battery.

On the 00, 01, there is a multifunction relay located (in my 01 anyway) above the fuse area in behind the dash, it's a grey box about the size of a pack of cigarettes. In it there are 4 or 5 relays, one of them monitors battery voltage when the vehicle is shut off. When battery voltage drops below a predetermined voltage, the relay kills the power saving the battery for effective start.

I repaired my multifunction relay board by re soldering all the traces on the PC board. The relay box is about $80 (dealer) if you don't want to tackle this. After I repaired the MF relay box, my trunk worked everytime, sunroof, radio and fuel door. And best of all, my battery drain problem disappeared. Its been 2 years now.