Weird sound coming from front driver's side wheel well area

[RAWeems]

Is anyone familiar with this part? Almost everyday and sometimes twice a day we hear it making a clicking sound like it's trying to start something or something is trying to kick in, then it stops on its own. Finally traced the sound to this part but no clue what it is running to. It's under the driver's side wheel well. TIA

[16ACE27]

Looks like a BIM to me:

[RAWeems]

Originally Posted by 16ACE27

Looks like a BIM to me:

And is it supposed to do that?

[16ACE27]

Originally Posted by RAWeems

And is it supposed to do that?

This isolates the house and chassis batteries when there is no charging occurring and connects them together when the converter is charging or the alternator is charging and there is sufficient voltage difference between the batteries that they would accept a charge.

[HarryS]

You can check its function with a volt meter. Check across the 2 large cables when it is not energized and you should read a voltage, somewhere between .1 and 2 volts, I'd imagine. When its energized, it should read 0 VDC.

[Judge]

What coach do you have? Several of us with the Omni / Magnitude have found it incorrectly wired by Thor. They had the house battery and chassis battery cables reversed on the BIM.

The way it works is.....

If on shore power and the chassis battery drops to 12.6V, the relay will engage (click) and the Converter will charge the chassis battery.

When driving if the house batteries drop to 12.6V, the relay will engage so the alternator chargers the house batteries while driving.

Finally, if the chassis battery won’t start the engine, the emergency start switch will engage the relay and connect the house batteries to boost for starting.

Bottom line it is normal to hear the click if the BIM determines the house or chassis batteries need charged based on whether the engine is running or you are on shore / generator power.

[RAWeems]

We have a 2020 Vegas 27.7 if we are hooked to shore power should it be doing this at all?

[Beau388]

Originally Posted by RAWeems

We have a 2020 Vegas 27.7 if we are hooked to shore power should it be doing this at all?

Yep, the BIM is using the coach's charger to keep the chassis battery charged even when the engine is not running.

[Judge]

Originally Posted by RAWeems

We have a 2020 Vegas 27.7 if we are hooked to shore power should it be doing this at all?

If your coach has the BIM160 or BIM225, the relay would engage if the house batteries drop to 12.6V so your Converter can keep them charged when on Shore Power or even Generator Power.

That being said.... the relay should not be engaging and disengaging continually. If that is the case, something could be draining your chassis battery (radio on, lights on, etc.) and causing it to drop down to 12.6V too quickly while the coach is sitting.

I have an easy test you can try to verify your BIM is working properly.


Shore Power Plugged In and Engine Off:

- Turn your headlights on without the engine running. This should drop the voltage down to 12.6V and you should hear the BIM relay engage so your Converter can charge the chassis battery. You can also put a voltmeter on your chassis battery or if you have the Firefly system the chassis voltage is displayed so you can see if you hear the relay engage when the voltage hits ~12.6V. You will see the voltage go up when the BIM engages.


Engine Running and Shore Power Unplugged:

- With the Inverter power on, turn down the fridge temp to max cooling so the compressor is running and turn on a TV that may be powered by the Inverter or the furnace to start dropping the voltage of the house batteries. When they hit ~12.6V, you should hear the BIM relay click on so the alternator. You will see the house battery voltage go up when the BIM engages.


Verify the Emergency Start Works

- With the engine off, press the Emergency Start Switch and you should hear the BIM engage with the house batteries boosting the chassis battery.


Doing these tests will help determine if your BIM is working properly.