12 Volt Power Suddenly Not Working!

[vwchappy]

Hi All! The other night we took out our fridge and had the 120V lights and 12v lights on (including outside 12v "porch" light) everything was working fine after the fridge was removed. We ran down to the bathhouse to get showered and came back and all 12v systems were OUT! Inverter was humming as normal. Put the multimeter on the 12V leads coming out of inverter going into the fuse block in the trunk and it showed 12v so we knew that was good. Continuity through all fuses (when pulled) and 12v coming off the fuse block but not all circuits. No battery is installed and never was. Everything has been working fine and all of a sudden it wasnt. No lights, no water pump but funny thing is, is my two leads that come out of the front cabinet for a car stereo which is currently not hooked up shows 12v. I don't get it!! Was working just fine and then No interior lights, no porch light, no water pump, but 12v on radio wires. WEIRD! I'm not aware of any other fuses/breakers or anything on the 12V system. Advice would be greatly appreciated.

[drboyd]

Did you check for +12V on both ends of the fuses with them installed? You might also look at your 30A battery fuses, both positive and negative (if your coach has them both like mine does).

[TG Twinkie]

You may still have a bad fuse. Especially if they are the old style glass fuses. They will cook slowly and leave a carbon track that looks like the fuse is good.
Questions:
Are the fuses as old as the converter?
Are the fuses tight in the holders?
Did you notice any hot or even warm fuses?
Have you tried new fuses?
Do you have a load on the radio wires? If not, hook up a 12 volt light and see if it works.
Let us know what you find when answering these questions.

[vwchappy]

Thams for your reply. They areally old buss glass fuses. We took each one out and put our meter prongs on each side and tested continuity. All fuses "beeped" confirming continuity. Are you saying they could still be bad? I have not tried new. Fuses did not feel warm to the touch. Input the tester on the radio leads and it showed 12v. It did not show 12v when I put the tester in a light socket. This is a 69 Sovereign if I didn't mention already.

[TG Twinkie]

Yes I am saying they could be bad. It would be relatively inexpensive to replace the existing fuses. It's worth a try. Don't forget the large (30 amp) fuses on the battery leads. One could be mounted separate, with the holder attached to the skin of the coach.
While you are in the fuse panel check for lose connections at the termination point of each circuit.

[vwchappy]

Thanks, I will try new fuses next time I head up. In the meantime, do you know where I can get a wiring diagram for 1969 Sovereign? I know I have buss fuses in the rear compartment, inverter on curb side rear compartment, main 30A breaker in bathroom closet, and other breakers in very front cabinet above the sofa. All 120v systems work. Just not 12v. No battery is installed and never was. Battery terminals are, and have been taped. I basically have no idea what each of the buss fuses do, so a diagram may be beneficial. Is that fuse block ONLY 12V stuff since the 120V stuff is all on breakers? Does the 12V DC system use a ground, or is it only a positive and negative coming off the inverter straight into the fuse block and then distributed from there? Thanks again.

[TG Twinkie]

The 12 volt DC system is tied to the frame or skin of the coach.
This means there should be a wire from the converter (not inverter) to the fuse block, the negative side of the battery and to the skin or frame. Chances are the wire is white.
The positive side of the converter should connect to the fuse panel + buss bar. It will likely have a 30 amp or so fuse.
There may be a fuse 30 amp on the negative side mounted somewhere on the skin.