Auxiliary Battery??

House battery for many Class C's is located in engine compartment - sometimes below stairs. As far as check engine light you need to get the codes pulled to determine why - many auto part houses will pull codes for you for free.

Check the gas filler cap for tightness first. CHECK ENGINE LIGHT fire sales are common. They get the light reset then dump the vehicle ASAP. In California the SELLER has to get ot smog checked BEFORE selling it.

anchor wrote:
Just acquired a 2003 Trail-Lite R Vision 21rb class C motorhome. Where is the house battery, if there is one?? Also "check engine light" won't shut off. Oil has been changed about 3,000 miles ago. (This is our 5th motorhome).
Thanks, Florida

Check engine light has nothing to do with a oil change.

Check engine light simply means there has been a recorded malfunction event which effects how the engine runs or emissions related faults.

You need a code reader to retrieve the code(s) that have been stored which triggered the light..

I see you have a Harbor Freight store in the town you have in your signature..

Located in SPRING HILL, FL #00470 2418 COMMERCIAL WAY.

HF carries pretty decent code readers and with a 20% coupon you can get one for about $80. That will be $80 well worth spending since it will save you from randomly throwing parts at it.

The nice thing about the HF readers is they not only give you the codes but they also will look up the codes and give you some basic troubleshooting info for those codes which will help to narrow down where to look.

Plug in blue tooth readers for tablets or after market gauge readers will often only give the error codes and you will have to manually look up what the codes are for.

Get a reader and post back the faults..

Check Engine may be translated on driver info if you have it, Else a code reader is needed, My car is currently tossing that light at me (I know why).

I use a Smart Phone. I installed Torque (pro) on it, in the documentations they show a number of devices that can be plugged into the OBD II port. one is called a "Cheap E-Bay Adapter" or something like that, May not work. That's what I have, works great.

I have one more month till I have the money turn that light out.. problem is NOT with the engine, (Which runs fine) the code is one of the support sensors, needs replacement (the sensor).

Something as simple as the wrong Gas Cap, or not putting it on properly, (remember the On-Star commericial with Kelly Rippa), can turn on that light.

wa8yxm wrote:
Check Engine may be translated on driver info if you have it, Else a code reader is needed, My car is currently tossing that light at me (I know why).

I use a Smart Phone. I installed Torque (pro) on it, in the documentations they show a number of devices that can be plugged into the OBD II port. one is called a "Cheap E-Bay Adapter" or something like that, May not work. That's what I have, works great.

I have one more month till I have the money turn that light out.. problem is NOT with the engine, (Which runs fine) the code is one of the support sensors, needs replacement (the sensor).

Something as simple as the wrong Gas Cap, or not putting it on properly, (remember the On-Star commericial with Kelly Rippa), can turn on that light.

Actually the OPs Ford chassis should have a separate gas cap light, I know my 2003 F250 does.

Will check the gas cap again. Will also try to get the codes for the "Engine" light. Thanks

The house batteries are usually in a battery compartment vented to the outside. Walk around the rig looking for vent slots in the compartment doors.

My first engine light reading cost $40 at a Dodge dealership. I immediately bought my own reader for $60. It gave pretty short descriptions but the codes could easily be looked up online for more information. I also have a $10 wifi reader from eBay that I can connect to with an iPhone to get the readings in a companion app. Apple devices don't work with inexpensive Bluetooth code readers.

No vents on the outside. This is our 5th RV in 25 years. Apparently with the generator, etc., there is none. Thanks

Found the codes and looked it up--"Evaporator Canister". Now trying out a exact copy of the gas cap and will disconnect the Positive cable for 30 minutes(?).

anchor wrote:
Found the codes and looked it up--"Evaporator Canister". Now trying out a exact copy of the gas cap and will disconnect the Positive cable for 30 minutes(?).

What is the exact code?

It most likely isn't the gas cap..

It is most likely an issue with the evap system although the cap becomes part of the evap system.

See THIS LINK for some of the possible codes for the evap system and some explanations..

Also , if you have a real code reader, you do not have to disconnect the battery to reset. You can use the reader to PROPERLY reset the lights (be aware in resetting the codes you may make diagnosing your problem harder since it will take multiple driving cycles to bring back any and all codes)..

Also removing the battery may not clear all codes (some codes can only be reset with a proper code reader) and on top of that your vehicle will need to relearn all the engine settings..

Engine light will most likely come back on in two or three driving cycles..

Check for any pending codes BEFORE resetting the check engine light and write all found codes down.. They will help pin point the problem.