Viofo Dashcam hardwire not powering up

[kitsune]

Hello everyone,

I've got a VIOFO A129 Dashcam and wanted to do a hardwire install. The camera has worked when powered by USB or from the cigarette lighter but when attempting to wire it up with the hardwire kit it does not power up at all.

To test the hardwire kit, I'm using the fuse box located in the back of the car as it is easier to access. I've found two fuses to tap into, using the volt meter I can see that they deliver around 12 volts constantly. They are both powered when the engine is running, I haven't been able to find a fuse that is powered when the engine is switched off though but I'm not planning on using the parking mode.

So I've plugged the yellow and red wires to the fuses and the black wire to a ground point. With the volt meter I can see 12 volts passing between the ground point and the black wire so there is a circuit from the fuse to the ground with the hardwire kit in between.

I've set the hardwire kit to the lowest settings which I think is around 11 volts, should be low enough not to cut off power to the dashcam.

So, I'm pretty certain that the hardwire kit is powered from my tests detailed above. When I plug the dashcam in I get no red light to show it is powered nor does the dash cam switch on. I've also tried enabling parking mode but it still does not indicate that it is powered.

Is there anything I may have missed or could do to find out why the dash cam is not being powered up?

Thanks

 

[Nigel]

You may need to start the engine before it powers up, although if you power both red and yellow then I believe it should start up anyway.

Check your ground wire is actually connected to ground.

With the volt meter I can see 12 volts passing between the ground point and the black wire

That is not a correct measurement, you should see 12 volts between the ground wire and the red wire, and zero volts between the ground wire and a real ground point such as the battery negative terminal. It is possible your ground point isn't connected to ground?

 

[Mtrev]

As Nigel says, if you have 12v between the black wire and ground then the black wire isn’t connected to ground.

 

[SawMaster]

Grounding can be tricky nowadays, as many exposed bolts either aren't grounded or have a torturous path to ground giving excessive resistance or intermittent faults. Best to look for a bolt which has factory ground wires attached. Even then you should check for current with the cam on between the black HWK wire and a known good car ground. If there's any current reading whatsoever, you've got grounding problems.

On my old Buick there were tabbed grounding plates under the door sills which were known to corrode, and that included the screw holding the plate to the frame. It was an area that collected water in the rain which led to numerous people having a car that would run roughly or stop running in the rain because there was too much resistance in the ground path for the engine computer. Easy to fix but he!! to diagnose as test lights showed no problem and those d@*% ground plates weren't evident unless you traced the ground wires leading out of the dash on both sides (yep, there were two of them). So be sure of your ground-test point by using a bolt going directly in the main car body, and if possible run your HWK ground there.

Phil

 

[kitsune]

Thanks, I'll try a different bolt. I believe there are two other bolts that appear to have grounding wires already attached so I will try those. I'm fitting into a modern car so not many points to fit ground onto.

 

[Mozzie]

Or splice into a factory earth wire

 

[Mtrev]

Even then you should check for current with the cam on between the black HWK wire and a known good car ground. If there's any current reading whatsoever, you've got grounding problems.

To avoid confusion as I’m sure it’s what you meant but it’s voltage that needs to be checked not current.
Anything over about 0.3V is excessive volt drop for a ground, obviously if the measurement in the original post is true then he currently has 12V of volt drop.

 

[SawMaster]

I meant current. With a load (dashcam) operating, there is current in the ground wire so if you can measure any current between that ground wire and a known good ground (car body) the HWK grounding point cannot be OK. If there's no current measured this way then there can be no voltage either, but most meters can resolve current (amps) to a greater degree then voltage, which makes measuring for current more effective than measuring for voltage in this test.

If your meter is able to resolve voltage to a mV or uV level then that can be used equally well. Just a matter of practical use of the equipment they'll likely be using.

Phil

 

[Mtrev]

I meant current. With a load (dashcam) operating, there is current in the ground wire so if you can measure any current between that ground wire and a known good ground (car body) the HWK grounding point cannot be OK. If there's no current measured this way then there can be no voltage either, but most meters can resolve current (amps) to a greater degree then voltage, which makes measuring for current more effective than measuring for voltage in this test.

If your meter is able to resolve voltage to a mV or uV level then that can be used equally well. Just a matter of practical use of the equipment they'll likely be using.

Phil

Oh Ok, not a test I’ve ever heard of doing but every day’s a school day. trying to picture the theory now lol.
Is that something that comes from an electronics angle and dealing with smaller values then? Like I note you mention uV which I’ve never needed when dealing with general automotive circuits and diagnosing them.
Interesting comment about the meters, I’ve generally found that cheaper multimeters have a tendency to be wildly inaccurate for current readings especially at lower levels, like monitoring current drain when a vehicle is asleep I’ve seen someone chasing a 0.3-0.4A drain when it should be below 0.05A only to then put a fluke branded meter which showed it to be below the 0.05A threshold all along.

 

[kitsune]

Hi, thanks for your help so far. So I managed to find a working ground point.

I'm now going to try hardwiring into the front fuse box. It looks like I have two powered cigarette lighters that I can use for now! However, there appears to be not many places that are grounded.

The only place that works is where the fuse box cover mounts too. Is this safe to use? As you can see the connector is meant for a bolt but is there a way of attaching it to this without making modifications to the car?



Thanks!

 

[Nigel]

Looks like the screw behind the yellow wire can be used. Remove it, put it through the earth lead connector, refit. Not ideal to have plastic one side, but should be OK for the low power use.

 

[Kremmen]

I was looking at the nut just left of the blue sleeve. Just needs a small crimp ring and Bob's your uncle

 

[kitsune]

Thanks everyone. The bolts attached to the fuse box don't seem to work. However, I unscrewed the bolts found on the outside of the panel below the glove box which exposes some bolts behind the cover.

I've attached the earth wire to this bolt which is then covered behind a panel so it is hidden away.



The dashcam is now powering up and all the wires are hidden.

 

[Kremmen]

This is a situation where a multimeter is invaluable. When I get my new car in a few weeks the multimeter will get used during installation for all wires, just to check the power and earth is as expected.

 

[SawMaster]

Oh Ok, not a test I’ve ever heard of doing but every day’s a school day. trying to picture the theory now lol.
Is that something that comes from an electronics angle and dealing with smaller values then? Like I note you mention uV which I’ve never needed when dealing with general automotive circuits and diagnosing them.
Interesting comment about the meters, I’ve generally found that cheaper multimeters have a tendency to be wildly inaccurate for current readings especially at lower levels, like monitoring current drain when a vehicle is asleep I’ve seen someone chasing a 0.3-0.4A drain when it should be below 0.05A only to then put a fluke branded meter which showed it to be below the 0.05A threshold all along.

Cheap meters do vary considerably, and you're right about accuracy being suspect with them. For the average user here any decent one will be good enough. But when doing a ground test where any figure above zero indicates an issue, it is only necessary for the meter to resolve between zero and anything above that. In my experience any meter will do that just fine, even if the above-zero reading is in error. If there is a meter problem here, then the display will not read zero before you touch the probes to anything making the meter problem evident.

As Ohm's law shows us, all three factors are involved with electrical flow so theoretically measuring any one of the three will show an above-zero condition, but understanding what the factors are and what they mean can help you to understand which one is best to measure for. For instance if you have a 50-strand wire and only one strand is making contact, it will carry (and the meter will indicate) any voltage you put through it under any load until the strand fails, but it will quickly lose current-carrying capacity as a load is added for a lack of the other 49 strands, so measuring the current will show a problem much sooner than measuring the voltage, and that's why I recommend doing it this way.

HWK's are designed to accept input voltages from roughly 11.5V to roughly 14.5V, with many if not most having an upper limit of roughly 26V we can presume that if the car starts and runs we're going to have voltages in the acceptable range. But we all know that dashcams need their minimum amperage (especially Viofo cams) or we have problems. Another reason to measure current instead of voltage, and the reason I'm adamant about using only the Viofo-supplied PS's and HWK's with his cams, or something known to be able to supply that minimum current level reliably. But we're now seeing several reports of these HWK's not working properly in more recent times which leads me to believe that something has changed with them, probably without Viofo's knowledge or approval as these are outsourced and not made by him. So @viofo and @VIOFO-Support can now look into the matter and find out where the problem began and rectify it for existing and future users, which I'm pretty sure will happen as Viofo does care about us more than many other cam manufacturers do.

Phil