Looking to tap switched/Acc circuit for rear dash cam.

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01dailey

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I'm planning to install a rear dash cam in my 2021 Yukon Denali and I'm looking for a source of power which will only be on when the ignition or Acc is on. I don't plan to use parking mode so I only need the two wire hardwire kit (GND/12V). Based on an earlier thread, the only switched fuse in the entire vehicle is in the Instrument Panel fuse box, F26 (USB/SEO RAP). Running a power wire the length of the vehicle to F26 is one option, but seems like a lot of work. There is a type C USB port close by. I assume there is some kind voltage converter module (12v to 5v) behind those ports which is fed with a 12 volt wire ? Could this be a viable source of power ? Would it be safe to tap it ? This USB port is part of the 10A circuit controlled by F26.
 

BlaineBug

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Are you running a front camera or just a rear camera alone? Typically dash cameras are 5 volt and require a step down from 12 to 5. They are essentially a glorified USB web cam.
 
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01dailey

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I already have a front camera and decided to get a rear one as well. Rather than getting the rear which goes with my front camera, the rear being a lower resolution extension that plugs into the main camera, I decided to go with an independent rear camera. You are correct, the dash cams operate on 5 volt. The hardwire harness kit contains a voltage converter (12v to 5v) which connects to the 12 volt system of the vehicle. The way I see it, I have two options here regarding the USB port. Simply plug into the USB port with USB cable (5v) and be done with it (not hard wire it), or hard wire it to the 12 volt wire feeding the USB port. The benefit being to not permanently occupy the port and to have the cable out of sight.
 
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01dailey

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I already have a front camera and decided to get a rear one as well. Rather than getting the rear which goes with my front camera, the rear being a lower resolution extension that plugs into the main camera, I decided to go with an independent rear camera. You are correct, the dash cams operate on 5 volt. The hardwire harness kit contains a voltage converter (12v to 5v) which connects to the 12 volt system of the vehicle. The way I see it, I have two options here regarding the USB port. Simply plug into the USB port with USB cable (5v) and be done with it (not hard wire it), or hard wire it to the 12 volt wire feeding the USB port. The benefit being to not permanently occupy the port and to have the cable out of sight.
Please excuse my ignorance in my previous posts. The ports are connected with USB cable to a hub. There is no 12v source. I will have to either plug into the USB port or route my power from the Instrument Panel fuse box back to the rear of the vehicle.
 

BlaineBug

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I can't tell you which fuse(s) you can use in your rear fuse box, but a fuse tap may be the way to go. That's the way I installed my dash camera, with the rear camera that plugs in to the front camera. I tapped up front though. No cut factory wires or splices in my install.
 
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01dailey

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I can't tell you which fuse(s) you can use in your rear fuse box, but a fuse tap may be the way to go. That's the way I installed my dash camera, with the rear camera that plugs in to the front camera. I tapped up front though. No cut factory wires or splices in my install.
There are no suitable fuses in the rear fuse box. Every fuse 20A and below has full time power, except for two (F12 & F49). These two have no power whether ignition is on or off. I'll tap F26 (USB/SEO RAP) in the front fuse box and route the cable to the rear.

I had quite an experience installing the front dash cam in my Yukon. I hard wired it using a fuse tap, but just couldn't get the camera to work. I then discovered there was no power at the camera end of the harness. I assumed that the voltage converter in the wiring harness (12v to 5v) must be defective. The next day the camera just came on by itself and worked fine, but only while the engine was running. I then discovered my battery was going bad. It won't charge up all the way and the in-harness converter was shutting off because the voltage was too low, as part of the battery protection. This week I'm getting a new battery.

WARNING: GMC strongly advises against using the OBD port to power devices of any kind.
 

BlaineBug

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What are the rear fuses without power?

Your only alternative is to run an extension wire from a switched source to the rear. My camera has parking mode too so it uses full time and switched power too.
 
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01dailey

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What are the rear fuses without power?

Your only alternative is to run an extension wire from a switched source to the rear. My camera has parking mode too so it uses full time and switched power too.
I don't care about parking mode, so I only need switched power which is my F26 fuse in the forward fuse box.

The unpowered fuses I found in the rear box (only tested 20A and less) were F12 'GBS' (Glass Breakage Sensor) and F49 'Lift Glass' (Rear Hatch Glass Release ??). I measured these two fuses with ignition Acc off and on and there was no power. F12 is an alarm sensor so maybe the fuse is powered when the alarm is armed. I don't know about F49.
 

BlaineBug

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I don't care about parking mode, so I only need switched power which is my F26 fuse in the forward fuse box.

The unpowered fuses I found in the rear box (only tested 20A and less) were F12 'GBS' (Glass Breakage Sensor) and F49 'Lift Glass' (Rear Hatch Glass Release ??). I measured these two fuses with ignition Acc off and on and there was no power. F12 is an alarm sensor so maybe the fuse is powered when the alarm is armed. I don't know about F49.
Do you know if there are any fuses back there for dome lights by chance? Off topic but since you've been back there and looked in to it. I've had the slight urge to add a cargo area dome light but really wouldn't want to go through the trouble of having to take down any other dome light in the vehicle as I hear they are a real bear to drop down from the headliner also often resulting in broken clips or brackets.
 
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01dailey

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Do you know if there are any fuses back there for dome lights by chance? Off topic but since you've been back there and looked in to it. I've had the slight urge to add a cargo area dome light but really wouldn't want to go through the trouble of having to take down any other dome light in the vehicle as I hear they are a real bear to drop down from the headliner also often resulting in broken clips or brackets.
There are plenty of fuses you could tap, but all are full time power. You could have a dome light that switches manually. I think the ideal circuit to tap would be an empty fuse socket not in use. I think there may be some which are powered. My second choice would be to find a safe fuse to tap, and don't tap anything greater in amperage than the rating of the fuse tap.
 

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