Strange electrical issue

I bought a wireless car charger to install in my truck. None of the crappy universal mounts satisfied me so I decided to make my own. Long story short, I removed the sunglasses holder and inserted it in the recessed space. I thought that would be perfect since I had power right there for the lights too.

Man was I wrong...My first mistake was tapping into what I THOUGHT was a switched 12 volts (though I did find it strange it was only reading 11.7). Turns out it actually had something to do with the traction control switch. Any time even so much as the 12DC-5DC converter was plugged in, the button would not function. So that was out.

I decided, since it only draws around 30mA on standby, to tap into the constant hot (12.7v this time). Now I've got a strange issue. When the overhead lights are on, the phone charger turns off (even if not charging, again only puling 30mA). What's more, if the lights are off the phone will charge fine pulling a full 1.5 amps. Could the overhead lights really be pulling so much current that the voltage is dropping on that bus? The only thing I can imagine is that the charger or 12DC-5DC converter is very sensitive to voltage drop.

BTW, I'm really happy with the install. I may post pictures a bit later when I have some time.

 

12.7 sounds low, should be 13.4'ish. Personally I would tie it into the cigarette lighter, that is 13.4 and rated I believe for 10A.

 

Is it a beige wire? Sounds like your tapped into the dome light supervision circuit. at rest its positive and is a negative trigger when active.

 

Nothing will be at rest around 13.4. A normal healthy car battery should be around 12.6 volts. Your reading should be around that or just under your battery voltage. With a vehicle running it should be around 13.8-14.4 volts. Could vary a bit depending on a few variables

 

You are both correct, it should be 12.6 or close to it at rest, however, the cig plug will not be powered while the vehicle is at rest, thus, the 13 plus volts at the cig plug, because it is only getting voltage when the vehicle is running. (or if in accessory mode, vehicle not running, then it will be 12v)

 

I see what he's talking about now. Thanks.

 

Negative was a black/white striped wire, continuity was traced to the negative of the cigarette lighter. The positive was more of a grey color. That does sound like a distinct possibility though. I wish I could find a wiring diagram but thus far I haven't found any service manuals for the 16's.

 

If your checking continuity with the battery connected then any wire that is resisting or triggering at ground is going to show continuity with an actual ground. Toyota grounds are usually white/black strip and that should be the color of the cig lighter. Not black with a white stripe.