Hello, I have a 2003 Camry I inherited from my late father. 192k miles, mostly highway, garage kept, essentially pristine. Over the last month or so there seems to be a battery drain problem, to where finally I came out the other day and it was completely dead. I mean, no lights, nothing. I've been busy but today I had time to put a charger on it. When I did the horn sounded, then the charger pegged to the right like it was a short, then pulsed with a frequency of what I imagine would be the horn's alarm, but the horn didn't sound. It sounded like something was heavy electric buzzing in the area around the fusebox, I checked that and all "looked" OK. I disconnected the battery and hooked the charger directly to the cables and it did the same thing. I checked the resistance across the cables without the battery and it showed about 10k ohms, rising. I've never seen anything like this. Any advice or assistance would be greatly appreciated. Thanks, JP

 

The alarm will go off if the battery is disconnected and reconnected. Try inserting the key into the ign before connected the battery or to silence the alarm.

Strange electrical issues can happen if a battery is allowed to go dead when still connected to the car.

To charge the battery disconnect a battery cable and then connect the charger. Assuming the battery is not internally shorted it should charge but may still have gone bad.

There is always some parasitic drain on the battery when the car is off such as alarm system. If after charging the battery and successfully reconnecting disconnect one cable and put an amp meter inline with cable and battery to check this drain. Thought normal drain was something like 15 ma but one can check on the internet.

Is possible a trunk or glove box switch is not turning off the light. On some years of cars the HVAC blower was coming on with car off due to a circuit board issue.

If things start to buzz with the battery reconnected have a helper with a section of rubber hose or such to use as a stethoscope. Prior to connecting the battery remove all the relay/fuse box covers. There is fuse box behind far left drivers side dash ash tray and one behind the drivers side kid panel by the left leg. The owners manual may have relay/fuse box locations.

If a relay is buzzing disconnect battery and find out what the relay controls. One can take picture and post it here.

Note Toyota has a technical website where for say $20ish one can access service info including wiring diagrams. The wiring is still reasonably simple in design.

https://techinfo.toyota.com/techInfo...a.com%3A443%2F