Parasitic battery drain

@tacoma_ca, Thanks again. Your concept sounds straight forward enough but I'll have to think about how to actually implement that as words like circuits, relays, diodes are not in my everyday toolbox. But hey, that's what TW and google are for right!?

 

Planning and analyzing simple 12V automotive circuits for lighting etc. is just like analyzing a sprinkler system in the yard and is fun once you figure out the basics. A relay is like an electromechanical sprinkler valve, diodes are like one-way valves, and the battery is like a pressure source. In conventional circuit diagrams, electrical current flows from positive terminals to negative terminals just like fluid flows in a pressure gradient. That’s all you need to know aside from figuring out how to solder and you are all set.

 

So as I continue down this saga of my parasitic drain,,, I figured I would replace my glove box light since it should be an easy fix and to check off the low hanging fruit of items on that Dome Circuit. In researching how best to pull out that tiny glove box bulb I see talk of an ash tray light....
I have an ash tray light?!
That's another light that hasn't worked in 10 years -- might as well replace that to one too.

 

Well, no joy with the Glove box and ash tray light being the culprit. Still pulling 196mA.
But boy, how fancy am I now... haha.

 

In case other are curious, It looks like these little lights (the ash tray and glovebox light) only come on when you turn on your headlights. They also come on no matter if your ash tray and glovebox are open or not. That helps explains why both of these lights were burned out when I first got mine. Before I replaced these little lights I would always drive with my headlights "on",, not anymore I guess if I want to keep those lights operational.

Does anybody else have working ash tray and glovebox lights in their 1st Gen that function the same way? Seems strange that Toyota would design it that way.

/dpw

 

Yeah I think my lights were the same till they burned out.

 

@tacoma_ca, Thanks.

Silly if that's really the way Tacoma wired it. Maybe they figured you would only need lights on in those places if the headlights were on,, but overlooked the fact that those little bulbs would burn out.

Well, anyways... back to the dome circuit investigation.

 

I finally gave up took my '03 to an auto electrical specialist (this after another shop confirmed what I knew but didn't want to dig into further).

So, with my radio disconnected, my draw drops to 25-35mA(it fluctuates every 8sec to the 35). That should fix the drain, but

What do you all think? Is the radio the smoking gun? Or perhaps something else?

Clues:

• Draw with radio connected is about 210mA.
• Electrical system is stock
• There are a few dash lights out (RPM and behind the AC knobs)
• The stock radio works fine (when it's connected)
• No other electrical issues that I notice.
• Yes, the battery and alternator are good

Thoughts?

The electrical shop thinks its something bad in the radio (even though it works fine..?) Suggested getting a new radio. A ~200mA draw for the radio does sound too high so I don't disagree, but with a new radio I wonder what the draw would be and if that would bump my draw up to the 50mA range which brings me back to the high end of what's acceptable.

Thanks all,
dpw

 

I tend to agree with the electrical shop. There's probably something internal to the radio that's causing the higher power draw, even if it seems to be working fine.

This might be a good excuse to buy a nice aftermarket head unit.

 

Definitely possible. You could dig around and try to verify, or easier, if you ever replace it you could hook the old one up to a 12V source and verify.

Cheapest fix is use a toggle switch to open the power circuit to the radio when you aren't using it. Or switch the main power with a relay that is controlled by the lighter sockets right there, in stock configuration those sockets are only on when accessory is active from the ignition key. This would make it act 'stock' again without that battery drain when off.

 

Yeah,,, thanks. I’m considering that. I’m sure there would be some nice aspects to a new unit. There has been a few times on trails when a rear-view camera would be a nice to have.

Any suggestions? I’ll have to look into all the options.

 

Don't have a specific head unit to recommend, but I do recommend you buy a radio from Crutchfield.
https://www.crutchfield.com/S-DprP3Qgshff/

One thing to remember is that if you want your steering wheel controls to work with the new head unit, you'll probably need a module to let the aftermarket radio talk to your steering wheel controls. Looks like those are only ~$60.

https://www.crutchfield.com/g_118900/Steering-Wheel-Audio-Control-Adapters.html?tp=3405

Happy motoring!

 

Thanks, I’ll check out crutchfield. No steering wheel controls on my 1st gen tho so don’t have to worry about that.

 

Thanks @tacoma_ca, I’ll have to look into that.

 

Update: I ended up picking up a "new to me" stock radio for my '03 here on TW for $65(thanks @Goober1997 !) and sure enough, my parasitic draw is down to around ~23mA. I think this issue is finally behind me now! Time to move on to more exciting things... like some mods!