Forum Discussion

jim427's avatar
jim427
Explorer
Apr 21, 2019

1999 Fleetwood Discovery 38 ft. battery relays

Recently I noticed a "buzzing" in the back of the coach when it is parked, on shore power, and both battery relays are in the on position. I finally found it in the battery compartment, and it was the 200 amp. SPST relay mounted on the wall of the compartment. I tapped on it and the noise temporarily went away, but later returned. Then I started the engine, and the 12vdc house lights came on along with the running engine, but then both died. After 3 cycles of this the engine and lights remained on, but that relay is now oscillating on and off when both the battery relay switches inside are turned on. Not knowing what's going on I am leaving both relay switches off until hopefully someone here has an idea what's happening. Is the relay now bad? I see it has a bolt head on top and thought maybe I could open it up and clean the contacts?? Any ideas are appreciated.
Class A
  • enblethen's avatar
    enblethen
    Nomad
    Apr 21, 2019
    Some use a continuous 12 volt control signal while others use a momentary signal to energize/de-energize relay. Identification of the relay is important.
  • wolfe10's avatar
    wolfe10
    Explorer
    Apr 21, 2019
    Check voltage to the small signal terminal (s). If 12+ VDC, the relay is bad. If one small signal terminal it will be the positive (with ground through the relay's body). If two, one will be the positive, one the ground/negative.

    You can also use a small jumper wire from the 12+VDC lug to the POSITIVE signal terminal after removing the wire to the positive signal terminal so you don't back-feed that circuit.
  • enblethen's avatar
    enblethen
    Nomad
    Apr 21, 2019
    Sounds like it could be low voltage on the control circuit. This could be from poor connections at the batteries. Voltage could be low through out the electrical system.
    Reason the lights cme on was the alternator was powering the lights through the charge relay system then voltage dropped turning system off.
    Start by cleaning battery cables.

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