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Q Why is my water tank level indicator erratic?
I have an Auto-Trail V-Line Sport, bought new in Nov 2018. It uses Sargent electrics.
The problem is with the fresh water gauge, which has rarely worked properly since new. It sometimes does work, but will then show various numbers (0, 25, 50 or 75), apparently randomly. On occasions I can even see it changing whilst watching it.
Annoyingly, when it changes to zero, the âtank emptyâ warning buzzer sounds. Infuriating if itâs the middle of the night and the tank is full! I have learned to live with not having any means of telling how much water is in the tank.
I have reported this several times to the Auto-Trail dealer and, whilst I do not doubt he has tried things (cleaning the tank and contacts), it has made no difference. Whether or not it is covered by warranty is debatable as there appears to be an exclusion for tank gauges. This spoils what is otherwise an excellent âvan. Is there any advice you can offer?
Jeff Outram
A The technical experts at Sargent said that, without seeing the vehicle, there are a few things that can be done to narrow down the cause of the problem:
1 By far the largest percentage (over 70%) of calls regarding sporadic water tank readings is calcium built up in the fresh tank or soap deposits in the waste. It is for this reason that we start with using a tank cleaner like Kilrock or similar and to drive around for a period to ensure that it cleans all of the probes/sensors. We are aware that some dealers do in fact use a professional tank cleaner to ensure the tank is thoroughly cleaned, others just run water through them.
2 The cable for the fresh tank sensor runs from the tank to the control panel through the harness. Th ere is a connector at the tank to aid fault finding. We would normally suggest that a technician disconnects this connector and then, by shorting from the negative (black core) to the other colours, the reading should prove the circuit (remembering that the system is an adder circuit so by connecting the black core to one other cable will provide a 25% reading; adding a second cable (so a total of three) will increase the reading to 50% and so on up to 100%). This is to remove the problem of the tank wiring being installed incorrectly and showing a non-linear scale.
If the above does not produce any reading, then it could be that the negative cable is broken or damaged. If it is damaged then by adding a separate negative to the water in the tank by temporarily putting a length of cable in the filler to the tank, with the other end connected to negative, may assist in diagnosing the problem (but that will not be easy unless a stiff wire is used).
