GreggyG

yup, that's the problem. Good news is that you have it diagnosed now and you can fix it.

Dustyis300

I also have same issue after heavy rain should i check for wet relay

chiph9

Yes. Please read through the rest of this thread as to why.

Chip H.

buddhi

This morning, no rain last night, and the battery is dead with the hazards flashing. Battery is new, an AGM Optima yellow-top, and was fully charged last night.
On the charger now. Disconnected the battery to stop the flashers. Battery seems way down. 2003 SC430 152k miles.

Did the flashers arbitrarily start flashing for some reason and kill the battery, or did the battery die for some reason and, for other some reason, the flashers
started up? Yesterday I hard wired a small Cobra radar detector into the overhead light, but the detector was off. That power is always on without the key on, but
still, how could it drain the battery if the detector was all off and no detector lights were on?

Also, I do not understand how a bad hazard relay could either drain the battery or start up the hazards. Makes no sense, does it? Like a wiper relay going
bad and turning on the wipers and killing the battery. Would a Toyota engineer do that?

chiph9

This is the GX470 forum, not the SC430 forum.

If the relay's contacts stick together (perhaps an arc welded them together strongly enough to overcome the strength of the spring) then yes it will run the connected circuit and possibly drain the battery.

I would definitely look at the radar detector with some suspicion. 1. You just made this change, and now you have a problem, and 2. Modern electronics never really turn all the way off. There is a small current used to power them all the time to look for the power-button to be pressed.

Chip H.

buddhi

Yes, GX, but exact same problem. Yes, most likely the detector. Will disconnect and see what happens, then reconnect.
Still, if that's the problem should just drain the battery. These are not supposed to be German cars.