Water level sensor

[southernscouse]

Hi the red light is constantly flashing if I bridge the connection at the tank sensor it stops if I then turn off the ignition and start again light works as it should so I think easy it’s the level sensor
How do I test this sensor. I have continuity from spike end to terminal on both pins but if I check for continuity between the terminals with the spike ends in antifreeze I get nothing how dose it work

[Mocki]

The coolant sensor is a resistor , its resistant changes when the prongs are in coolant .

Clean the prongs well

If you bridge the connections after you unplug the sender it should make the light stop flashing , if the sender is unplugged and not bridged it will constantly flash

Also check the connections of the control module 42/43 in the fuse board or up above it , corrosion or dirty connections will alter the resistance it is getting

[southernscouse]

Thanks mocks the sensor in the tank is spotless pulled the 43 relay and swapped it for a spare of unknown condition red lint working as it should swapped back to the original light working as it should must be connection swapped back to my spare as the contacts looked a lot cleaner will hopefully give it a run tomorrow. Thanks

[southernscouse]

Still not taken for a run yet because today the flashing red light is on again put in new level sensor still flashing bridged the terminals still flashing pulled relay43 still flashing
Turned the engine off put everything back tried a few starts light still flashing went through turning on all dash switches when on full beam light went out did this a few times light went out every time I now suspect earths but which ones. Thanks

[Robsey]

There are two crowns on the A pillar above the fusebox.

You may as well clean all of the earth wires (brown wires).
I cleaned mine to shiny metal last year.

Applied a smear of vaseline / petroleum jelly to keep moisture out.

And then reconnected up again.

Hopefully that will last for as long as you have the van.

[southernscouse]

Have done this before in the distant past but last year fitted the slaughterhouse dash rewire and thought all my troubles were over thanks I will get that done

[AngeloEvs]

In your recent post you stated that the  LED is flashing constantly with Relay 43 removed.  If that is the case, and the temperature gauge reads normal then the coolant level sensor and that part of the circuit has been isolated and cannot cause the problem.    The temperature gauge has a small circuit inside that pulses the LED, this internal circuit is triggered when the ignition is first switched on and is also triggered by Modue 43 (or 42 may be fitted) when coolant level falls.  The Temperature gauge has three connections with the centre connection providing the Earth for the Gauge internal circuit, it gets its  voltage from the 10v regulator.      The circuit is very sensitive to voltage fluctuations and earth problems which trigger it.    The Earth track on the blue ribbon membrane is also used by the Main Beam Led, Glow Plug LED, Panel Lights, the DOPS system board and the 10v Regulator.  Any issues with those certainly points to an Earth problem from Dash to Chassis.

You need to check the following:-

1.     The dashboard Earth terminates at the crown connection next to the fuse box, common for poor earths at this location (this has already been mentioned in previous posts).
 
2.    The Temperature Gauge securing nuts are tight.   The nuts connect the temperature gauge to the Blue membrane Earth and also to the  10v Regulator supply, they can become loose and cause earth and voltage fluctation problems.

3.    The condition of the Copper tracks where the 14 way multiconnector fits. This is best done with dash removed and the black plastic shroud that the edge connector fits into uncliped and removed. 

4.   With dash removed, inspect the Voltage Regulator. This is held by a self tapping screw and fits into a socket.  Remove it from the socket and visually inspect the condition of the legs and clean them if necessary. Then re-fit

With the dash out it is an ideal time to bench test it but you need a 12V DC supply and a pair of leads with small crock clips (if you want more info then happy to supply)

If the LED flashes continually on a bench then the gauge itself needs to be tested.


 
Unfortunately, as these vans are now aging and over 30years old, many owners will experience continual flashing of the Temperature Gauge LED due to failure of the internal circuit.  The gauge internal circuit has an Electrolytic Capacitor which  needs to be replaced - unfortunately, Electrolytic Capacitors have a service life and all will eventually fail.    The capacitor is under the PCB but, once removed, it is easier to fit the replacement on top of the PCB as seen in a gauge that I had to repair recently for someone.  The replacement is a miniature 10uf Tantalum and costs a few pence. I can give more details if you want them.