A few weeks ago my mechanic did the wiring for my dash cam. He hooked it up to the car stereo wiring so it'd have continuous power for what's called "parking mode" on the dash cam, which allows it to sense motion around the car and then record even when you park it. He was going to run the power from the fuse box and run it to the inside but said hooking it up to the radio would be a lot easier and still do the job. The car is now wired for the dash cam, but the dash cam is hooked up yet.

I rehooked my Garmin GPS up to the car and plugged it into the cigarette lighter yesterday but it wouldn't work. I figured the cable was toast. I looked around for a replacement cable but then saw the cigarette lighter adapters that allow 2 USB hook ups. I thought that'd be good because then I could run the Garmin GPS and charge my cell phone at the same time. The adapter that I bought is a 5v one.

Poof!

Blew a 16 amp fuse. I'm guessing that it would not be wise to put a bigger fuse in the socket (which runs the radio, headrests, and a bunch of other stuff).

What can I do? I can get a single USB adapter instead of a dual USB adapter and just hook the GPS into it. But when I hook the dash cam up to it, it'll need power too and could blow the fuse again.

How can I get all this stuff to work? The Garmin requires a 4.75 to 5.25 v input, otherwise it will think it's in computer mode and think that my car is going to give it a map update.

Thanks,

1991 300d, 221k

There are lots of other circuits to tap. Since the GPS and your phone charger are unlikely to matter if the car isn't running, you don't need an always-on circuit. So something like the glovebox light should be a convenient circuit to tap.



The USB shouldn't draw all that much current, maybe 2A tops when both segments are charging drained device batteries. How much do the radio and dashcam draw?

It there a spot for accessory wiring built into the w124s? I don’t know everything about it. But I’m pretty sure there are terminals inside under the dash somewhere that are connected to open spaces in the fuse box

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Jeremy has a thread about the 124 power distribution center in the driver footwell. IIRC that’s where seat heaters draw power so it’s plumbed for serious amps - W124 Electrical Option Connector "X30"

I hooked up a 12v to 5v converter with mini (or micro?) USB wire for my dash cam. It’s on the lighter circuit with no issues. Only live in ACC or run though. It caused a ground loop when wired to the radio in another car.

I helped someone sort wiring in a Lexus and found the professionally installed phone charge cable was an aux lighter socket with USB adapter tucked in the dash.

Sixto
98 E320 wagon
02 C320 wagon

You are absolutely right about not going to a higher capacity fuse. Fuses are their to protect the wiring and components and burn before the limits of either are reached.

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84 300D, 82 Volvo 244Gl Diesel