Need Help! No voltage to stereo ground wire

[tkielich]

One day the radio went out and would not turn on at all. thought the stereo was faulty was gonna replace with another unit but tested all wires for power and i had no power coming from the stereo ground wire going into the head unit. Not sure what to do about this. do i need to replace ground wire?

[chpthril]

I would hope to not find positive voltage on a ground wire. However, would hope to find negative, or zero, voltage on it. So if you meter's ground lead was connected to a known boat ground and you touched the meter's positive lead to the head unit ground, you should have found no voltage.

What kind of voltage did you measure on the head unit red IGN and yellow MEM/B+?

[lee]

[tkielich]

im not sure ill have to try and check again on the voltage, but shouldn't i get some kind of power from the ground wire?

[chpthril]

You should not measure ANY voltage on a DC ground.

Now, using the ground as one leg of the circuit you are testing, you should measure positive battery voltage on the other leg of the circuit. But again, the ground is the zero reference and the "power" is the positive reference voltage.

[gumby]

[freeheel4life]

You should not measure ANY voltage on a DC ground.

Now, using the ground as one leg of the circuit you are testing, you should measure positive battery voltage on the other leg of the circuit. But again, the ground is the zero reference and the "power" is the positive reference voltage.

Dont forget tho, if your meter is grounded and you read 12v on a ground then you have an OPEN on the ground.

^^obviously not for your reference Mike but rather others that like using a meter.

[tkielich]

Thats what i thought. I am able to get power from the accessory wires by bypassing the ground and using the 12v output on dash. However i dont get anything from the stereo ground wire under the dash. When i turn the stereo switch on dash the light comes on but there is no voltage coming from the ground wire to power the stereo. I really am not sure what to do.

[chpthril]

Dont forget tho, if your meter is grounded and you read 12v on a ground then you have an OPEN on the ground.

^^obviously not for your reference Mike but rather others that like using a meter.

Yes, exactly, IF you read voltage on the ground, you have a bad ground, but we dont want to read voltage.

[lee]

Did you check the flux capacitor for voltage?

[chpthril]

Thats what i thought. I am able to get power from the accessory wires by bypassing the ground and using the 12v output on dash. However i dont get anything from the stereo ground wire under the dash. When i turn the stereo switch on dash the light comes on but there is no voltage coming from the ground wire to power the stereo. I really am not sure what to do.

Heres what I like to do:

Meter ground lead on head unit chassis or stud on back, meter POS lead to yellow. Should read battery voltage. if we read battery voltage, we tested both circuits in one test and all is good. if we dont read voltage, move POS lead over to amp's POS power cable. if you now read voltage, the issue is on the head unit yellow B+. If you still dont measure voltage. issue is likely head unit ground. Move meter's ground probe to amp's NEG cable and touch amp POS cable. Should read battery voltage. Now touch POS lead to yellow. If you read voltage now, you proved bad head unit ground.

Once you know the head unit ground and yellow B+ are good, now move to the red turn-on. This should have 12V battery when either the key is turned on, in ACC or if your boat has a stereo rocker.

[freeheel4life]

Sorry I confused the situation. Mike's explanation is spot on. I do things a bit differently and just use a long lead grounded to battery then I can wander through the boat with meter and simply use the POS lead of the meter and then I'm not trying to do 2 things at once while reading the meter.
Regardless, you shouldn't read power on the ground, which is what it seems like you are looking for. You should read 0.00 preferably if your meter is grounded and you are probing a ground wire. In actuality you will probably see 0.02 on an auto ranging meter or something close to it.

[tkielich]

Before testing what was said above, now i dont have anything on my dash working. When i hit the switch to turn on the blower, bilge, etc. I dont get any response. just the light comes on when i hit it. Although with the battery on i am able to turn the key and turn and boat on and all the gauges work fine. Really confused

[Mr_T]

Heres what I like to do:

Meter ground lead on head unit chassis or stud on back, meter POS lead to yellow. Should read battery voltage. if we read battery voltage, we tested both circuits in one test and all is good. if we dont read voltage, move POS lead over to amp's POS power cable. if you now read voltage, the issue is on the head unit yellow B+. If you still dont measure voltage. issue is likely head unit ground. Move meter's ground probe to amp's NEG cable and touch amp POS cable. Should read battery voltage. Now touch POS lead to yellow. If you read voltage now, you proved bad head unit ground.

Once you know the head unit ground and yellow B+ are good, now move to the red turn-on. This should have 12V battery when either the key is turned on, in ACC or if your boat has a stereo rocker.

I am having a similiar problem as described in this thread. What is the next step if there is no power to red turn-on? I also have no power to blower. 2014 Tige z3. Thanks

[chpthril]

I pity the foo that dont tell what year and model boat

Ill presume we are talking about the red turn-on at the back of the head unit? This is generated by the ignition key switch on most boats. I would then go there and prob the ACC terminal on the back of the switch with the switch in ACC and RUN. it should have battery voltage in both key positions.