Forum Discussion

hotjag1's avatar
hotjag1
Explorer II
Feb 04, 2015

Update:::Unidentified Electrical part on Allegro Bus



This part was bolted onto the left rear frame rail beside the transmission. It has a 6 gauge cable(wire) attached to the battery side, and a smaller wire(16gauge)attached to the aux side. Both terminals were corroded, so I was removing the nuts so that I could clean them, but the threaded stud on the battery side started to turn and cracked the housing.
Does anyone know what this part is? I've been told by the RV places that it is either an isolator, relay, or some sort of circuit breaker.

It is on a Freightliner chassis. I called Tiffin, but their tech was busy and I did not leave a voicemail. I'm hoping someone on here recognizes this part or replaced it. I don't know if it is Tiffin or Freightliner

Thanks for any help on this.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Another argument in favor of circuit breaker over diode isolator

    NO HEAT Dissipation fins.

    Diode isolators develop heat,, a fairly large amount of it, so they have fins.
  • With looking at one picture my guess is circuit breaker. 16 g wire is only good for about 20 amps max so that breaker shouldn't be over 15 amps or so. I would replace it with a type 3 manual reset. Those automatic types are fine until you have a fault that makes it keep tripping. If it continues to trip, it finally goes into melt down and welds to the ON position and takes out the wiring harness. Not real common but I have seen it a few times. It's cheap and easy to just upgrade to manual reset. I would agree to find out what is on that circuit before determining the breaker size.

    The reason another 16 gauge wire may be on the side with the large wire is because they ran a hot wire to another device.

    One example

    2
  • RoyB's avatar
    RoyB
    Explorer II
    l would contact TIFFIN Allegro Bus with photos and location of the component.

    Being only two connections marked BAT and AUX I would lean towards a BATTERY SYSTEM component and most likely a DIODE BASED ISOLATOR. However most DIODE BASED ISOLATOR requires THREE LARGE CONNECTIONs if used in the POSITIVE TERMINALS of the battery systems..

    This could very well be high current AUTO RESET RELAY CONTACTOR.

    I have been scanning the internet without any good results. Was even able to look through a couple of USER MANUALS PDFs for the Tiffin Allegro Bus.

    I am just guessing like all the others here...

    Roy Ken
  • While it is off, try to find out what does not work. Be sure to insulate the wires of course.
  • ScottG wrote:
    btcruzer wrote:
    That may be a cheap part that is readily available at O'reilly's but I don't believe they have ANY $3 parts. A 15 cent bolt costs about 89 cents there.

    One question, why 6 gauge wire on one side and 16 gauge on the other if this is a circuit breaker?


    The supply end probably had the bigger wire.
    There are many reasons they aren't the same size;
    Could be it came from somewhere where it was just handy to use that AWG or they may have been concerned about a V drop or the may be other options that could have been connected to the load side requiring more current.


    Thank-you for the replies. I also was wondering why one terminal had a much heavier wire attached compared to the other one. Thank-you for the explanation on that.

    One thing I didn't mention was that I originally took the part to Napa. There is no amperage mark on it that we could see, and he thought it was an isolator.

    There also is a 14 or 16 gauge wire on the same terminal with the 6 gauge wire. How can I determine correct amperage for a circuit breaker?
  • btcruzer wrote:
    That may be a cheap part that is readily available at O'reilly's but I don't believe they have ANY $3 parts. A 15 cent bolt costs about 89 cents there.

    One question, why 6 gauge wire on one side and 16 gauge on the other if this is a circuit breaker?


    The supply end probably had the bigger wire.
    There are many reasons they aren't the same size;
    Could be it came from somewhere where it was just handy to use that AWG or they may have been concerned about a V drop or the may be other options that could have been connected to the load side requiring more current.

    Circuit breakers
  • That may be a cheap part that is readily available at O'reilly's but I don't believe they have ANY $3 parts. A 15 cent bolt costs about 89 cents there.

    One question, why 6 gauge wire on one side and 16 gauge on the other if this is a circuit breaker?
  • usnretired92 wrote:
    It is not a relay because it does not have any control wires. It looks like a like a diode to keep auxiliary power from feeding back to the battery. The arrow stamped in module is the key. Since you have a Freightliner chassie you need to contact Freightliner for info.


    That's not an arrow. It's a simple curb between the terminals of the breaker to keep the connections from touching - a common characteristic.

    OP, put an ohm meter across it to check continuity just use a light bulb connected to one end and connect the other end to the battery. You'll find it will have continuity no matter which direction you hook it up - proving it's not a diode.

    BTW, just because it's cracked doesn't mean it wont work. As long as it doesn't get moisture in it and corrode it will function. If it does corrode inside then it will trip prematurely.

    You don't need to contact FL for a replacement unless you want to spend about 10 times what it's worth. Just get the current rating off the side of it and go to NAPA or Oriellys ~ it's a $3 part.
  • It is not a relay because it does not have any control wires. It looks like a like a diode to keep auxiliary power from feeding back to the battery. The arrow stamped in module is the key. Since you have a Freightliner chassie you need to contact Freightliner for info.
  • That's an auto resetting DC circuit breaker.
    It should have a current rating on the side.
    You can get an new one at any auto supply house and they're very cheap.
    BTW, they are not polarity conscious even though Batt/Aux is embossed on them. That's only there to keep the questions down.