Forum Discussion

Arnie_G's avatar
Arnie_G
Explorer
Aug 13, 2015

Lighting wierdness

Hi,

I recently bought a 1976 Vagabond Class C. It's built on a Ford E350. We've had it out a few times already and have had a blast with it. For a 40 year old vehicle it's doing great.

But now I have something odd happening with the interior lights.

1) If I turn on any one of the interior house lights it comes on, but one of the Exterior running lights at the back also comes on.

2) If I turn on any second interior light, both interior lights that are on dim a lot and now I have 4 of the back running lights on.

3) if I turn on one or two of the interior lights and go sit in the cab and turn the headlight switch to dim the dash lights, the interior house lights also dim.

4) When I bought it a couple months ago it didn't do this.

Any ideas as to how I can track down what's happening? I have no idea where to begin.

Thanks,
Arnie
Class C
  • ron_dittmer's avatar
    ron_dittmer
    Explorer II
    Aug 17, 2015
    Arnie.G wrote:
    Thanks everyone! I crawled under and looked for any wires connected to the chassis this morning. The second one I found and wiggled fixed the problem. Now I just have to clean it up and fix it permanently. But it sure feels good to know exactly where the problem is.
    Awesome you found it, and quickly too!
  • Arnie_G's avatar
    Arnie_G
    Explorer
    Aug 17, 2015
    Thanks everyone! I crawled under and looked for any wires connected to the chassis this morning. The second one I found and wiggled fixed the problem. Now I just have to clean it up and fix it permanently. But it sure feels good to know exactly where the problem is.
  • klutchdust's avatar
    klutchdust
    Explorer II
    Aug 14, 2015
    First place I would check is the outside coach lights, turn signals etc. for corrosion and possible misplaced bulbs. Once had a semi come into the shop and when he turned the signals on all

    the marker lights blinked, had an 1156 in a 1157 socket and it was feeding back, corrosion can do that also. Most likely a ground somewhere. i wouldn't check the ground with a jumper I

    would remove it from the chassis, clean and refasten. Like what was said, start with clean secure connections first. Let us know what you find.
  • ron_dittmer's avatar
    ron_dittmer
    Explorer II
    Aug 14, 2015
    j-d wrote:
    Watch out for weak and failed GROUND connections. Your batteries (chassis and house) should be securely grounded to the coach chassis. Your house wiring should be grounded back to the chassis too. If ground isn't solid, a light you turn on can try to "find" a ground through another light. That light may in turn light, or glow.
    That is what immediately popped into my head.....one or more corroded ground connections. Corroded chassis ground connections is a very common problem in older rigs....even newer rigs that are driven in winter where salt spray messes them up.

    Clean up each ground connection you find, typically an eyelet on the end of a green or black wire, held against a piece of metal frame with a sheet metal screw. Replace the screw, maybe even cut a new clean end and add a new eyelet. Once it's all back together, Smear a good amount is silicone grease to slow down future corrosion.
  • Matt_Colie's avatar
    Matt_Colie
    Explorer II
    Aug 14, 2015
    Arnie,

    I trouble shoot DC systems a lot (did more before the depression) and I can tell you explicitly that you have several bad grounds. So, start there and when you get the lights to isolate (on the light you turn on, comes on). Then if you have strange things happening, start looking at the supply side.

    This is going to take you some time and thinking. For starters, that interior light that brings up the running light probably does have a bad ground and it is sort of common with the running light's ground.

    This will be worth the effort in the end as you are going to fix a number problems you did not new you had.

    Matt
  • Arnie_G's avatar
    Arnie_G
    Explorer
    Aug 14, 2015
    That's great now I have some things to look at. So I should be able to take a wire from the ground side of the lights to the chassis and see if that fixes it, then I'll know I have a loose ground wire to find.

    So both batteries and all wiring systems should all be going to the same chassis ground, is this correct?

    Thanks so much for the help everyone. I'm taking it for a weekend getaway tomorrow. I'll just not use the interior lights this weekend and try to troubleshoot it next week. I appreciate the help!

    Arnie
  • j-d's avatar
    j-d
    Explorer II
    Aug 14, 2015
    Watch out for weak and failed GROUND connections. Your batteries (chassis and house) should be securely grounded to the coach chassis. Your house wiring should be grounded back to the chassis too. If ground isn't solid, a light you turn on can try to "find" a ground through another light. That light may in turn light, or glow.
  • gbopp's avatar
    gbopp
    Explorer
    Aug 14, 2015
    Make sure your battery terminals are clean and the batteries are charged and working properly.
    Start your investigation with a good power supply.
  • Johno02's avatar
    Johno02
    Explorer
    Aug 13, 2015
    Check for a shorted bulb. You are gonna have to do come circuit tracing. Get your meter out and have at it. You have a short between the exterior lights, and the power lead to the interior lights, and voltage is feeding from the interior lights to the external light sircuit. Probably be a good idea to locate this pretty quick, it could cause a lot of other problems.

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