I spent all my time turning wrenches and know nothing about wires so be patient with me please. I am replacing a water heater in my motor home and the wires that come from the 12v battery source do not match the standard colors. I have an Orange, a pink and a yellow wire to connect to my water heater switch. My question is using a multi meter (which I am not good at using) how would I determine which is the "+", "-" and ground? Sorry for such an elementry question but I obviously know little to nothing about electricity. Thank you.

 

Welcome to the forums.

I think this topic will do better in its own thread.

 

You find the water heater manufacturers installation manual.

 

Well, start by connecting the red test probe to the Volt/Ohm/mA jack on the meter, and the black test probe to the Common meter jack.

Turn the meter's knob to measure in the 20v range, or at least a range that is higher than you expect to measure.

Try measuring across the battery terminals for starters. Place the black test probe tip on the negative (-) terminal, and the red test probe tip on the positive (+) terminal. If the battery has been fully charged and then allowed to sit for several hours, you should read around 12.7v to 12.8v. If the meter indicates a negative voltage, like -12.7, you know that the polarity is reversed.

I don't know why your heater has three wires. One might be ground, one might be battery +, and the 3rd wire a low-power on/off switch.

I am not familiar with RV wiring nor RV hot water heaters.

 

The water heaters I've seen in RVs typically run on propane (for example, in my trailer). There are no electrical wires to it at all. Unless you post your RV manufacturer and model and some forum member is familiar with it, your best bet may be to talk to the service department of an RV dealer -- they might be willing to give you the information.