I have a side marker light that is a bit dim. When I check voltage I find that it is lower than it should be. Between 11.5-12.0 Volts. I am getting 13.1 volts at other light sockets. I am assuming a bad ground. I have traced it back as far as I can with no luck. Can I ground that fixture to its own ground and solve the problem? Is there a negative to doing this?
12 Volt Grounding Question
- Thread starter bigpemby
- Start date
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SeilerBird
Well-known member
No negative, ground away.
John From Detroit
Well-known member
First.. To check if it is a bad ground or a bad connection on the positive side measure voltage to a DIFFERENT ground point, one that you know is good, (Either another lamp or even all the way back to the battery. negative. (I have lots and lots of wire on hand for this kind of thing)
IF it is a bad ground. Any good chassis connection point can double up on the ground, I do not like having two grounds on the same lamp but a pair of wire cutters can fix that.
Most ground issues are where the wire connects to the chassis, Just clean and re-tighten.
IF it is a bad ground. Any good chassis connection point can double up on the ground, I do not like having two grounds on the same lamp but a pair of wire cutters can fix that.
Most ground issues are where the wire connects to the chassis, Just clean and re-tighten.
Icemaker
Well-known member
- Joined
- Oct 12, 2011
- Posts
- 967
John From Detroit said:
Other than "just because" what is the issue w/multiple grounds? I'm not asking this because I disagree but because your reason may influence me in the near future as I've lost my rear upper lights due to a PO backing(?) into something and the ladder smashing a fixture. I replaced a blown fuse after replacing the light and still have no voltage. If I add a ground will it cause problems?
Gary RV_Wizard
Site Team
Actually, we are talking about a single ground point (the negative terminal of the battery) but with multiple paths to it. That is a non-issue. Multiple separate grounds is not good electrically, since the ground path should return to the same source as the positive side, but even that is not much of a concern in an RV. That's because in an RV, both the house 12v system and the chassis (running lights, etc.) use the vehicle chassis as ground, so you really can't go far wrong. The two 12v systems share a common ground.
Lou Schneider
Site Team
- Joined
- Mar 14, 2005
- Posts
- 13,231
In DC circuits, the only issue is possibly backfeeding current from other circuits along the multiple ground path and overloading the wire. This isn't an issue in the lighting circuit we're discussing, but might come into play if you have multiple grounds elsewhere. For example, you have a heavy strap ground going to the engine block that carries all of the starter current. If the large strap fails, the circuit opens and no starter current flows. If there's a smaller wire giving an alternate path from the engine to ground, it will be forced to carry all of the starter current if the main strap fails.
Definitely is a ground issue. I am going to try and trace it down before running a new ground. From what I can tell so far, it seems it could be going to a lug on the chassis where the horn (not air horn) is mounted. I am going to pull the bolts loose and clean and see if this solves the problem. I also have a bad ground to my HWH leveling panel. I am losing about 0.5 volts and it causes the HWH panel to read low voltage and not kick in. I have been connecting my battery charger to the chassis batteries when this happens to overcome the problem, but now I am hoping that this rusty lug on the chassis may be the common ground problem for both issues. If it is, I will be a really happy camper. Will post back when I test this theory. Going to work on it some more later today. Thanks
