aux battery wire problem

[Tnash542]

Hello every one  i have  a  94 ford E350 c class dutchmen  the battery that runs the 12 for the lights in the rv  has three wires that are all red wires no black ground wire to the frame  . one is a thick red wire  that must for the generator. another is for the charging for the battery from the other battery .. and the other one that is 12 gauge wire looks to go all the way back to the camper is this wire the one that charges the battery when plugged into 110v  or it a gound wire that is red, looks to be factory done. all the pix  i see on line there is a ground wire going to the frame.  no sure where the battery is getting its ground

 

[Alfa38User]

The only way I know would be to trace the heavy wire from the Negative (-) battery post. If you don't see one, look for a broken terminal on a wire hanging down in that area. Colour may not mean much but red is normally + and Black is normally - or ground. Its makes life easier when the normal colours are used but.......

 

[Just Lou]

Are you saying that there is NO wire/cable at all on the negative terminal of the battery?  If that's the case, I'd look around the area for it laying loose.  It should be a fairly large gauge cable (not a small wire).

 

[John From Detroit]

First: There is no "Standard" there is a tradition but no defined standard for wire colors.. I have seen negative cables that were RED.  And I've seen idiots hook up jumper cables backwards.

IF there is no wire on the negative side.. Then here is the test procedure.

First. Disconnect wires from the POSITIVE side..

now hook up a good ground wire, (Get one at Auto Zone, Discount Auto, Wal*Mart, Pep Boys, Or any other automotive supplier with the proper terminals,,  Provided you do NOT have an inverter it will be big enough,, I mean a BIG inverter.

Now,  Bolt one end to a clean spot on the frame or metal chassis and hook the other end to the negative battery terminal.

NOw you need a light.. I would recommend a 12 volt Incandescent trouble light at least 50 watts.  (The above list of auto stores)

Hook one lead of the trouble light to the POSITIVE, Then touch the netative terminal to make sure lamp is on and get a "Base line" for dead short brightness.

now move the negative clip to the Long heavy RED wire..  How does the light respond? (on off dim bright or Bright then dimming swiftly)

If no light turn on some interior lights. if they work, Disconnect, if the interior lights no longer work, Connect to POSITIVE post.

NOTE: if you get no reaction at all from the largest wire, Hold it for later.

now try the next smaller wire Basically same procedure  Also try things anything like the battery disconnect that does not now work (it might be the wire for the battery control system power, or the steps).

And finally the smallest wire.

Now any wires that do not respond....

Plug into 120 volt, move battery clip to NEGATIVE and see if one of those wires now has power,  If so, Positive.

And start the engine, wait one minute and if that wire now has power POSITIVE.

NOTE: the reason for the 50-100 Watt trouble light is it will pass enough power to light one of your interior lamps (Possibly 2) and at the same time protect against short circuits... Smaller lamps won't pass enough power.  ANd larger, not practical.

Test lamps such as this are a very valuable tool as I've had cases here where a volt meter said "All good" but the lamp diagnosed the problem and enabled me to fix it.  WHY,, It presented a LOAD to the circuit.