Crossed wires

[SCAdventure]

Not a problem with my Grady but with my deck boat. It has analog gauges that all work fine however when I put my running lights on the voltometer pins down below 10 volts and the the fuel gauge show up to full. This does not happen when I only put the mooring light on.

Any thought where to start?

thanks

 

[seabob4]

The fuel gauge pegging to full is a dead giveaway. You have a bad ground. Check the ground terminations on your running lights.

 

[SCAdventure]

Thanks but here's a stupid question. Would they be at the fuse box, the battery or the rocker switch? Thanks

 

[seabob4]

Mike,
Tighten your negative batt cable, check all the grounds on your gauges and ground bus under the helm. Just as in a car, a ground issue can be hard to track down. But a ground problem is the source of 99.5% of 12VDC issues...