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Diesel Filter Water Drain Valve, How Does It Work?? Think Mines Missing

t1pper

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Aug 7, 2014
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340
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uk
Hi,

Time to change the diesel filter on my 1999 100 diesel, got a new genuine Toyota filter all ready to go when I noticed the previous owner had fitted what looks to be an incorrect filter without the water drain valve, its a closed canister type, made by "Boshi".

The new Toyota one has a hole in the bottom for a water drain valve, I also found a 2 pin plug under the filter that looks like it should have had a water in fuel sensor attached to it at one time.

Do I have the correct Toyota filter with the hole in the bottom?
Am I missing the drain valve with an in build water in fuel sensor?
Lastly how does the system work?

When I turn the key on there is the amber warning light that comes on for a few seconds then goes out so the dash bulb etc must be good, however what looks like the sensor plug has an open circuit (nothing attached) when I shorted the 2 pins in the plug with some wire the lamp did not come on, so not sure where I am with the system???

Thanks in advance
 
Hi,

Looking at the Parts Diagrams I find two diagrams:

This is what I have in my 2001 100 'VX'. There is the electric float valve screwed into the bottom of the diesel filter. The float will float in water, but not in diesel, therefore when/if there is water in the filter the float rises and triggers a solenoid valve at the bottom that drains the water down a tube on the nearside inner wing.

This is different to the 90-Series where there is a hose with a drain valve that one drains periodically into a container to check for water.

This diagram shows the optional fuel heater components that I don't have.


FuelFilterwithOptionalHeater001_zpsaad64fd4.jpg



The second diagram shows the same filter as above, but also shows a "Pre-Filter" assembly, again, I don't have that on mine.


FuelFilterwithPre-Filter001_zps3d0339c7.jpg



It sounds as though you are missing the electric drain valve assembly on yours. Your new filter sounds right as there should be a large threaded hole in the bottom.


The part number for the switch/valve assembly is:

84461B (84461-28040) Switch, Level Warning

It has a guide price of €107.60.


There is a "with pre filter" version that is cheaper:

84461B (84461-60050) W (Pre-Filter)

This has a guide price of € 73.60.

Presumably the latter doesn't have the electric drain valve as all water should have been trapped by the pre-filter !

Hope this helps :thumbup:.

Bob.
 
Thanks Bob, that was a very detailed response, from this info it looks like I do not have a pre filter system and my drain valve is missing.

I would like to revert it to the original system so will have to sorce a new valve with a water in fuel senor, however I can not get my dash warning light to come on when I join the 2 pins in the plug together.

How does the sensor work work? Do I have a wiring fault as well?
 
Just a piece of info on the pre-filter. It was installed on what TMC calls General Countries version, sold in Africa and the gulf states. The pre-filter is a cheap(er) cartridge filter which is good for areas with bad diesel quality, e.g. sold from drums, made for beeing changed more often than the main filter.
 
However I can not get my dash warning light to come on when I join the 2 pins in the plug together.

How does the sensor work work? Do I have a wiring fault as well?

I am not aware of a light on the dash. I think the water drain system is automatic and just opens the valve when the float rises in water.

From memory it just has a two-pin plug - do you get 12 volts across the pins with the ignition on ??

Hopefully there isn't an ECU involved anywhere :icon-rolleyes:.

I'll have a look at the wiring diagrams and post-up what I find :thumbup:.

Bob.
 
My 90 series and 2013 Hilux have a dash light
The drain valve isn't automatic, there is a manual valve at base of filter which I always open when in process of changing a fuel filter



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Hi,
I do have a lamp on the dash for "water in fuel" and it breifly iluminates when the key is turned on.

I was assumeing the job of the sensor was either opening or closing the circuit depending on float hieght and any draining was a manual operation not automatic, however and this is the bit I think I have trouble with is if the light is off with an open circuit (no senor present) why won't the light come on if the circuit is closed (pins joined in the plug)??

Do I have a fault else where??
 
Well, it seems I was wrong, I have a manual drain valve at the bottom of my diesel filter, I just didn't recognise it as such.

I also have an amber dash light showing a picture of an in-line filter with a drip underneath it :thumbup:.

I also have the diesel heater on top of the filter housing, I should pay more attention when doing maintenance :oops:.

I had a look at the wiring diagrams in the Ellery Manual and all I can find relating to the fuel filter warning light is this (highlighted in yellow):


CombinationMeterWiring-1A001_zps23a0dcfa.jpg



It doesn't help much I'm afraid as Ellery take a 'black box' approach to wiring diagrams :lol:.

If I knew what a 'Combination Meter' was it might give me a clue as to where to look.

Hope this helps in some small way.

Bob.
 
Hi,
Thanks for the wiring diagram Bob.
It looks like I imagined the float in the sensor is just a switch, it appears that it makes an earth to iluminate the dash light, I will have a good sniff around and see what I can turn up.
Only one thing that is not clear what component is shown by the "JC" icon below the sediment switch on the wiring diagram??
 
Only one thing that is not clear what component is shown by the "JC" icon below the sediment switch on the wiring diagram??

I have had a hunt through the manual but it doesn't say what the JC, HC, EP legends are (or they are well hidden) - I suspect they are types of connectors.

I thought that the 'Combination Meter' was the dash - but wasn't sure - its a strange way of describing it.

Bob.
 
I have had a hunt through the manual but it doesn't say what the JC, HC, EP legends are (or they are well hidden) - I suspect they are types of connectors.

I thought that the 'Combination Meter' was the dash - but wasn't sure - its a strange way of describing it.
Combination Meter is the assembly in the dash which contains 6 gauges (2 big, 4 small) and most of the warning and status lights.

JC is Junction Connector. I.e. a plug.
HC is Harness Connector, a bigger plug.
EP is Earth Point. I.e. The electric potential zero volt.
 
Easy when you know uHu !!

Thanks everyone for the help and answers, I will report once I have had a chance to test the system.
 
Hi folks.

Im seeking some advice, as I recently installed a new fuel filter assembly on my 2009 HZJ 78. Everything is good, but the new filter has a heating element, which is ideal for the location where I live at this time of year. Only problem is, I can't find any wiring diagram to illustrate where to plug the heating element into (the original fuel filter had no heating element, the new replacement is out of the V8 and 100 series I believe). Its a simple two prong plug, and my other question is if I have to jimmy up a connection, it should be to a relay only on startup (like glowplugs?), or should the heating element be running all the time. Would appreciate any insight into this... its -12 here today!
 
Looks like the fuel heater is a self contained system with a built in thermostat that needs only ignition switched power. See attached EWD.
 

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