I need an electrical diagnostic sanity check - tap microswitch

[BruceM]

I need an electrical diagnostic sanity check before I start dismantling the bathroom.

 

The issue:

In my van the (submersible) water pump is activated via tap micro-switches.

The bathroom sink tap suddenly stopped activating the water pump.

All other bathroom tap switches (ie shower and toilet) work just fine.

 

Diagnostics so far:

I immediately suspected the tap micro-switch. To verify, I’ve exposed the micro-switch (see pic) and measure 13.43v across the cables (I have solar active). However when I join the cables together the water pump is not activated. So what am I missing? I’ve checked all the fuses on the EBL 99 to rule that out.

 

I’m assuming that the micro-switches feed back to the EBL which then activates the pump?

I’m also assuming that the micro-switch leads will be consolidated into a single lead to route the signal to the EBL?

 

So I’m puzzled how come the defective tap's cables are showing 13.43v but not activating the pump when connected together.

 

Before I start dismantling the bathroom to access the underside of the tap and its wiring it seems wise to get a diagnostic sanity check from you guys.

 

[Alanb]

One of my common warnings is that modern multimeters are very sensitive, and can give a plausible reading via a high resistance connection.  I frequently advocate the use of a simple test lamp as an alternative.

Perhaps your problem is one of those cases. Try a sidelamp bulb between the wires.  If pump is connected directly to the microswitches, then the bulb should glow, possibly without the pump running as insufficent current will flow.

If bulb does not illuminate, try the live wire to a separate earth via bulb. If bulb is at full brilliance, the live wire is OK, and the fault is between tap and pump.  Conversely, if the bulb does not fully illuminate , then the supply connections are suspect.

Alan

[BruceM]

Thanks Alan, good call. It was a high resistance connection. So it turns out that the microswitch had failed after all. Diagnostic sanity restored and now ordering a new tap.