Thetford Cassette Toilet Electric Flush Failure - Schematic Diagram request (2009 T@DA)

FuzzyYanni

Thetford Cassette Toilet Model 400 - Schematic Diagram Request ! (We have a 2009 T@DA, but any diagrams will be helpful)

Our Thetford Model 400L flush is no longer flushing.
I have tested and replaced the 3A blade fuse underneath I have visually inspected all wires behind the WFCO and inside the trailer for mouse chewing/ droppings, none were found.

I have scoured the internets for a wiring schematic / electrical troubleshooting chart from Thetford but have not found anything) I found the "Thetford Casette Toilet 400 - Complete Repair Instructions.pdf" in the files section of the facebook group (that I uploaded a few years back) and while it is excellent if you know what needs replacing, it's not a guide for troubleshooting

 The problem: I believe a part of the Thetford pump / flush system has electrically failed (2-Pump, 3-Vacuum Breaker, 4-Electric Valve, 5-Control Panel, 7-Relay, 8-Wire Harness, 11-Reed Switch).

From the WFCO, the 12V circuit fuse is tested and working, BUT when removed, the red LED is not lighting up on the WFCO. The red LED indicates a dead fuse and only lights up if the remaining circuit is complete. This leads me to believe somewhere along the wire, either the line is cut (chewed by mice) or one of the above mentioned components (see diagram) has failed in a closed (shorted position) and is no longer connected to ground.

If this is accurate, the WFCO cannot complete the 12V circuit, and removing the fuse at the WFCO does not cause the LED to light (indicating good circuit, bad fuse)

So my quest is to electrically test the Thetford components (voltage test/continuity/resistance) and determine which component has failed, before I randomly start replacing parts.

***Thanks for reading this far***

FuzzyYanni

Update - none really! I just ordered the pump from Thetford and I will install it, no troubleshooting or anything.
Hopefully it will fix our issues.

Stay tooned.

Verna

@FuzzyYanni, it would be helpful if you mentioned which T@B model you have, seriously. As soon as you mention “400”, my mind was thinking “there is no cassette toilet on the T@B 400”. So, deductive reasoning says you must have a T@B 320 or a T@DA. 

Anyway, to those who might help, I’m have discovered @FuzziYanni has a T@DA and can anyone help him?  I do read that @FuzzyYanni only wants comments from those who can help, so IF you can help, this pertains to a T@DA Thetford Cassette toilet. 

(As far as I know, there have been no reports here about cassette toilet problems in the T@B 320’s. )

—Changed model type because the OP has a T@DA

FuzzyYanni

Thanks for the tip Verna! I updated the original post to be more clear. 

The trailer is a TADA but all of the trailers with the Thetford cassette basically have a very similar Thetford System ( it's the Thetford Model 400, or very slight variants to the 400 system)

Any schematics would be nearly identical and most appreciated.