Talk to me about electricity as you would to a toddler

[Spectre]

What do you mean by that? They uses fuses overrated in respect to the wire gauge? I find it hard to believe.

Yup. Some makes used fusible links - GM most notoriously - and others used slow-blow fuses. In either case, sometimes the fuse or link wouldn't blow until the melting (or fire!) had started. And there were a lot of pre-67 cars that didn't have fuse protection of their horn circuits at all.

It's not just ancient cars that had this - IIRC GM is still using fusible links for the horns on some models as is Nissan.

In still other cases, the relay switched power source for the horn is on a circuit with something else and the fuse is sized so you can blow the horn while operating whatever else is on that circuit. Sometimes the fuse won't blow if the thing(s) that share the circuit aren't on or aren't drawing much power. Been there, done that, put the smoldering wires out.

 

[Perc]

I seem to remember from a forum discussion somewhere on the internet that there are some cars that have the headlight relay soldered onto the circuit board in the gauge cluster. Can't remember what car that was, but you should keep things like that in mind before you swap your halogen bulbs for that aftermarket HID kit that needs five times more current to light up.

 

[LeVeL]

I'm planning on wiring my dashcam using an add-a-fuse-

Am I correct in thinking that the charger wire needs to be stripped: the power wire needs to go to the add-a-fuse, and the ground wire needs to be, well, grounded (against metal)?

 

[CrzRsn]

Don't forget you likely need a power converter. Most dashcams run on 5V (aka USB voltage) while most of your car's electronics are on 12V circuits. I used this one when I wired mine. Double check your camera's voltage requirements before connecting it directly to the add-a-fuse or assuming its 5V.

Also, if you have a auto-dimming rearview mirror, it might be easier to just tap into that since likely it would have a "hot in run" connection going to it and is a very minimal use - which is exactly what I did.

 

[_HighVoltage_]

Some cars have a hidden (somewhere under the dash) auxiliary accessory plug that lets you get ground and power (12V as well as rheostat) without splicing wires or adding fuses.

CrzRsn is right about the power converter though. The car will supply 12V and you need only 5V.

 

[CrzRsn]

Some cars have a hidden (somewhere under the dash) auxiliary accessory plug that lets you get ground and power (12V as well as rheostat) without splicing wires or adding fuses.

CrzRsn is right about the power converter though. The car will supply 12V and you need only 5V.

I've never heard of this. Sounds suspect, especially with a rheostat from the factory. Maybe vehicles destined for commercial use that are generally upfitted (you can order Super Dutys with factory blank switches for extra lights, plow controls, etc), but an ordinary consumer product? Doesn't sound likely.

 

[_HighVoltage_]

I've never heard of this. Sounds suspect, especially with a rheostat from the factory. Maybe vehicles destined for commercial use that are generally upfitted (you can order Super Dutys with factory blank switches for extra lights, plow controls, etc), but an ordinary consumer product? Doesn't sound likely.

http://new.volvocars.com/ownersdocs/2000/2000_SV70/00sv70_06.htm#pg107

Tried and working. I find it surprising that most cars wouldn't have something like that.

 

[Spectre]

95+% of cars don't have that. That looks like they were planning to install some sort of instrument pod or something else there then decided against it too late to change the wiring harness. The *most* you can expect from most car designs is that there's a +12V and ground connection that was going to an aux power point that never got installed. Also, those Scotchlock splices are *evil*.

- - - Updated - - -

Don't forget you likely need a power converter. Most dashcams run on 5V (aka USB voltage) while most of your car's electronics are on 12V circuits. I used this one when I wired mine. Double check your camera's voltage requirements before connecting it directly to the add-a-fuse or assuming its 5V.

Also, if you have a auto-dimming rearview mirror, it might be easier to just tap into that since likely it would have a "hot in run" connection going to it and is a very minimal use - which is exactly what I did.

Pretty much this, though some cars' autodim power wires are only powered when the lights are on - and some don't have enough power to run the mirror and the dash cam. A better option for some scenarios is if you have overhead map lights at the front of the headliner - those can be key-switched and usually are, plus they're usually intended to handle a lot more power.

If your dash cam uses any sort of USB plug, it's going to be 5V and you will need a power converter. This is the one I used in my last install, which I came to after BCS steered me in the right direction with his Jeep's install. Rather pleased with it, but I'm trying a different tack with my next install. I used a standard Belkin USB A to mini B cable for the rest of the run up the windshield.

 

[CrzRsn]

http://new.volvocars.com/ownersdocs/2000/2000_SV70/00sv70_06.htm#pg107

Tried and working. I find it surprising that most cars wouldn't have something like that.

95+% of cars don't have that. That looks like they were planning to install some sort of instrument pod or something else there then decided against it too late to change the wiring harness. The *most* you can expect from most car designs is that there's a +12V and ground connection that was going to an aux power point that never got installed. Also, those Scotchlock splices are *evil*.

I thought you meant the car had a cigarette lighter style plug hidden somewhere behind the dash.
I'm going to side with Spectre here. I'm guessing that in some market somewhere in the world, Volvo uses that plug for some module, and rather than having a separate wiring harness, they just marked it as an accessory plug. Its rare because its expensive to provide extra plugs (believe it or not, adding the extra complexity of a unique harness without the plug is cheaper than throwing the plug in for free in most, but not all, cases), especially for a feature that's going to go largely unused as most people that are buying cars these days are not going to be fiddling with the wiring.

Pretty much this, though some cars' autodim power wires are only powered when the lights are on - and some don't have enough power to run the mirror and the dash cam. A better option for some scenarios is if you have overhead map lights at the front of the headliner - those can be key-switched and usually are, plus they're usually intended to handle a lot more power.

Obviously consult a wiring diagram to find out which lines are powered when since every car is unique. LeVeL, for your TL, It looks like the map lights in the over head console are not hot-in-run. The mirror has a hot-in-run lead going into it - the yellow/green one if you start taking it apart. The green one in the mirror connector is coming from the reverse switch on the trans to override the dimming when you're backing up.

If your dash cam uses any sort of USB plug, it's going to be 5V and you will need a power converter. This is the one I used in my last install, which I came to after BCS steered me in the right direction with his Jeep's install. Rather pleased with it, but I'm trying a different tack with my next install. I used a standard Belkin USB A to mini B cable for the rest of the run up the windshield.

I highly recommend using this over what I did. I currently have my USB mini-B connected directly to my power converter, which is great for all cameras using that connector, but if in the future I want to get a new camera that happens to use the new mini-C connector or something else proprietary, it will be a minor rewiring, whereas Spectre's suggestion will make it a much easier cable swap.

 

[Spectre]

Also makes it easy to replace the cable if it gets damaged - which is less likely as the USB cable has armor/insulation better than what you're likely to come up with for your own wiring.

 

[Matt2000]

Now I'm not suggesting that this is a good idea but you can now (or more commonly since it's probably been available for years) get an OBD2 power cable with 5V converter for dashcams.

 

[Spectre]

This is a remarkably bad idea.