QuestionQUESTION: I just bought the 3" VRVD630 stereo about a month ago. Everything was working fine until my battery in my car drained overnight out of the blue. I got the battery recharged and now my battery is showing its low again. This didn't start happening until I installed the new stereo. I have all the wires on corrected right,but I had to wire my blue (parking brake) wire to my yellow (power/fuse). Now I don't know if I have a bad battery which I only had for 2 or 3 year, or what could drain my battery so fast?
ANSWER: Hi Krystal,
I'm assuming that the new head unit is turning off like it should when the key is turned off. If not, then there may be a wiring problem; if it is, then you'd need to test to see whether the head unit is drawing more current than it should when it's shut down. The best way to do this is to use a multimeter with a DC current function.
When the vehicle is off, the only live power connection to the radio should be the yellow power wire. The current flow through this wire should be very small--just a few milliamps. You can test this by pulling the head unit out of the dash, and cutting or disconnecting the yellow wire. Set the meter for DC Amps (or DC mA if it has this function) and connect one probe to the vehicle side of the yellow wire, and the other probe to the radio side. This will make all the current flow through the multimeter, so you can get a current reading. If you get a reading higher than about 10 mA, then it's likely that the head unit is defective. (You may see a higher reading briefly, right after the wire is connected; but it should settle quickly to the normal level).
If you don't have a multimeter handy, or don't want to pull the head unit, you can try pulling the vehicle fuse that supplies the constant power to the head unit. This might not be the fuse labeled "radio", depending on the vehicle. (If you can tell me the year and model of your car, I might be able to help you find the right fuse). If the battery drain issue stops when the fuse is removed, then it's likely that the radio is causing the problem--or possibly something else on the same circuit.
Keep in mind that a standard automotive battery isn't designed to be completely drained--this damages the battery. If it goes dead too many times, you'll need to replace it, no matter how old it is.
Hope this helps!
Brian
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QUESTION: So my make and model is 97 Honda civic. And ill go out and buy the meter you said cause I won't to see if it is t stereo. Thank you so much for the help.
ANSWER: Hi,
In your Civic, the radio's constant power fuse is located in the small fuse box under the hood, at the back of the engine compartment on the passenger side. The fuse is a 7.5-amp and is labeled "backup". Once you have your meter, you can probably do your current testing right at the fuse location. Remove the fuse, and attach one meter probe to each fuse terminal in the fuse box. In this way, the current would be routed through the meter, just like it would if you cut the yellow wire and did your testing there.
The only problem with testing at the fuse, instead of at the radio harness, is if there's any other electrical device sharing the circuit with the radio. For example, if there's a clock in the car, it might be powered through the same fuse. Then, if you found a high current draw, you couldn't be sure whether the problem was at the radio or the other accessory. In your Civic, though, I don't think there's anything else on the circuit, and the testing would be a lot quicker and easier at the fuse location. If you do get a high current reading, then you can always repeat the test at the radio wire to be certain.
Good luck!
Brian
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QUESTION: So I tried the meter and the reading came out -0.002 when I tired it to the fuse alone I tried it with the system on and off. I also tried it to the yellow wire itself and it didn't read anything. So I rewired the wires and tried turning the stereo on and it wouldn't even power up, so I swapped out the fuse and got it to power again. When I told it to the mechanic they said it wasn't my stereo causing the problem. I then took my car to a friend of me and my partners and he cleaned up my cables and the battery heads or whatever you call them. It hasn't done anything wired for a day so far but we are going to take the car back to see our friend tomorrow to see if the battery is still showing low. I just wanted to see if you maybe had any ideas? Thanks so much for the help.
AnswerKrystal,
If the fuse was bad, that would explain why you didn't get a reading on the yellow wire when you tried it. It doesn't sound like the radio is drawing more current than it should be, judging by the results of your testing at the fuse.
It's possible to test the current draw of all the vehicle's electrical components at once, similar to the way you tested the radio current draw. This is done by disconnecting the negative battery terminal, and connecting the meter between the negative battery terminal and the battery cable. Then all the current being used by the vehicle is routed through the meter, and you can see whether there's enough current to drain the battery. The total current when the vehicle is completely shut down should be less than 50mA (.050 amps). Don't turn the key on while the meter is connected like this, or you're likely to blow a fuse in the meter.
Mechanics call this a "parasitic drain test". The way it works is, if you get a high reading, you'd start going through the fuse box and removing and replacing fuses, one at a time, until you find a fuse that makes the current flow drop when you remove it. Then you can follow up on that circuit and see if you can find the problem.
When you're testing, you'll want to switch off the dome light so that it won't come on when you're opening and closing the doors, because the current draw through the light will show on the meter. I don't remember if the Civic has lights under the dash; if it does, you should remove them, or take out the fuse that supplies them with power. If your car has a light under the hood, it should be disconnected too.
Hope this helps!
Brian
