Diagnostic: Coolant level sensor; must restart to test

[Marcq]

[crazyvwvanman]

The blinking led is a dual alarm. It blinks to get your attention when the coolant temp gauge reading is too hot and it blinks to let you know that the coolant level looks low in the main tank and you need to check the level asap.

The gauge itself has some electronics inside. This part can slowly go bad and make the led blink at times when there is nothing wrong with either the temp or the coolant level. This gradual electronics failure can be the most annoying to track down.

The failing electronic part inside can be replaced for $1 but it isn't at all simple unless you are already used to working on delicate circuits with a soldering iron. Replacing the gauge is the usual fix.

One easy test that may help is to wait for the next time it flashes when you know the level in the tank is ok and the needle isn't reading hot. Simply pull the "coolant level warning relay" from the dash relay/fuse panel. It is plugged into relay socket 3 and should have a large 43 or 42 stamped on the end you can see. With the led blinking away, just yank that relay out and see if the blinking immediately stops. If it still blinks then chances are you have a gauge with failing electronics inside.

Mark

[Marcq]

[Marcq]

[Marcq]

Back to square one everything was fine until I unplug the sensor on the expansion to see if it would start flashing, but it took about 3sec and it flashed and now it does the same thing

Basically, the gauge operates properly as long as I don't use the driving lights

Yanked the relay and it kept flashing so I guess I need a new gauge

Marc..

[menotti]

[menotti]

[menotti]

[menotti]

[menotti]

Any thoughts on this? Sorry for double posting in the other thread too

[Ahwahnee]

I would think the telling thing would be the level of coolant in the pressurized tank when the light is flashing.

I am still unclear whether you have a cooling system issue or a sensor/wiring issue.

Once you know which then you can begin to parse the possible causes.

You should probably pick one thread or the other to discuss this (or even start your own with a title specific to your problem).

[menotti]

[crazyvwvanman]

You need to do the relay test again when this temp gauge led blinking happens.
Yank the coolant level relay without turning anything off.
If the gauge blinking keeps going with the relay now out, IT CAN'T BE anything to do the the sensor, coolant level, or sensor wiring.
IT CAN'T BE!!!!!!

Now it is possible to have more than one problem happening at different times to cause blinking and that can really drive you nuts. You have to fix each problem.

Mark

[wcdennis]

The capacitor in the gauge that causes the erroneous blinking, will probably not fail decisively. Instead, it my be fine when cool and then short-out when it gets warm. This can make diagnosis very frustrating. As others have said, pulling the coolant relay is the best way to narrow down the variables when trying to solve the constant blinking LED issue.

[menotti]

[Black'n'White]

Found this thread while attempting to diagnose a flashing LED on the temperature gauge in the tach. '87 Syncro, Subaru conversion, aluminum expansion tank from Van Cafe, the level sensor in the tank only has one lead to it, and the tank itself is grounded (0.2 ohms resistance from the tank to chassis ground). Is it correct that the level sensor grounds through the aluminum tank?

This all started when the plastic overflow tank ran dry, so I suspect there's a small leak somewhere in the system. Filling the overflow tank to the max line didn't change the behavior.

Here's what it does:

Turn key to ON, LED flashes several times, stops, then about ten seconds later continuously flashes as long as the key is on. If I start the van, it does the same thing with the ten second pause. The goWesty blue film replacement kit is installed on the instrument cluster, along with the low coolant level beeper, and boy, does it get your attention!

I've got continuity in the blue/green wire from the expansion tank level sensor to the blue green wire on both sides of the big connector to the instrument cluster.

I measure 0.2 Ohms of resistance between the aluminum pressure tank housing and ground.

I opened the expansion tank and it is full to the brim. I pulled out about 500 ml of antifreeze with a turkey baster and the resistance across the sensor to ground dropped from about 32kOhms full to 22 kOhms with the level down an inch or so.

Shorting the level sensor lead to ground doesn't alter the flashing of the LED.

While the LED was flashing, I pulled relay 43 and the flashing stopped. If I plug the relay back in, after a short delay the flashing starts again.

Has anyone got a correct value for the sensor resistance range?

I'm running Prestone green antifreeze mixed 50/50 with distilled water. The engine only has about 400 miles on it at this point, so I don't think it's a corrosion problem.

Any ideas on what to check next? I'm running out of ideas...

Thanks!
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...

[VicVan]

Check this out:

http://www.vanagonauts.com/index.phtml?catid=241
_________________
'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[JRAMIREZACOSTA]

THANKS for the post, I tried almost everything you mentioned but, not to ground directly the blue/green wire.

[Black'n'White]

Just to follow up, my problem was resolved by replacing the coolant level sensor relay, the one with 43 painted on it in the bank of relays under the left end of the dash. Mine came from Van Cafe.
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...

[Black'n'White]

Update:
A few weeks later and the LED is flashing again, even with the new coolant level sensor relay installed. If I pull the relay when the engine is running and the LED is still flashing, the LED continues to flash.

I've replaced the capacitor in the temperature gauge, but will check to make sure the replacement is installed correctly, polarity wise.

If the capacitor is OK, what else should I check?
_________________
'87 Syncro/Westy Homebrew
Whatever it takes...