My car is draining battery even with ignition and light off

The parts you put in are not the source of the problem. You may have had some defects in those parts but now the true source of the battery drain needs to be fixed.

There are some testing machines Dealerships have that plug into the wiring loom and show whether something is shorting out or not turning off. These machines shorten diagnosis times but as car models change it gets expensive to have all of these machines. With your 1999 model, an experienced mechanic may have seen this problem before and will know what to check.

You need to be careful and Web search for wiring diagrams if trying to fix this yourself. Some wiring to the car computer is sensitive. With the battery disconnected an ohmmeter can show whether a circuit is grounding when it should be off.

Often a relay can refuse to release a connection when it is shut off. That means power can still go to the part that the relay connects and the battery will drain.

Some major drains can be the rear window defroster. Power window relays or sound systems can drain a battery too.

Alot of things. Could be a short or a bad diode in the alternator. Or even as simple as a bad relay.

if short trace fuses if no fuses are blown test and check battery cables and connections if parasite drain then the following links will assist you
How to Find Parasitic Battery Drain How To Perform Parasitic Draw Test EricTheCarGuy How to do Parasitic Battery Drain Test

Hi.

First ensure that battery is OK. If battery drains while driving, then the problem is related to alternator. Check that there is no problem with dome light or other device staying on because of a shorted switch.

If the rest is OK and battery drains when the truck is parked, check for contacts that may result in parasitic drains. See : Parasitic Battery Drain.

Regards.

Ginko

First try to understand if there is a parasitic drain.

Once you exclude the drain, replace the battery, a battery with shorted cells can cause the drain.


The firmware has nothing to do with drainage, unless the unit is factory defective.

To measure drainage remove ignition key, connect the amp meter between the battery positive wire connector and positive terminal.A couple of milliamps drainage is normal, and is caused by instruments, car stereo memory, ECU etc.
Start removing more fuses , and open the wiring at different points , trying to locate the problem.
Remove the fuses and see if you have drain by connecting a meter to read amps on battery, if you have drain with no fuse, then the problem is insulated to wiring harness before the fuse, with something shorted between the battery and the fuseblock.
Also check car stereo and car amp HU, the HU can keep a unit on when the ignition key is off, causing drain.