Flashing red light frequency changed!

[Smcknighty]

https://www.brickwerks.co.uk/header-tan ... early.html" onclick="window.open(this.href);return false;

This is brickwerks - similar, e.g there's a section that could be cut


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[Smcknighty]

https://www.brickwerks.co.uk/coolant-le ... sh-on.html" onclick="window.open(this.href);return false; do I just cut the tank then? Anyone ever done this? I will mess with those wires and see if they trigger


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[Smcknighty]

The connector next to the fuel filter had been cabled tied back there by someone in the past.. I checked the wires with multimeter - not live, bridged them, no impact on light. What would be the expected test - I'd have thought bridging them?


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[marlinowner]

Have you got a "relay" 42 or 43? If not then the coolant level warning won't work.

[Smcknighty]

Looked in Bentley - the diagram indicates it should be threaded and screw in to the tank which makes sense.. so I'm kind of stuck - does it just get deleted if you buy a replacement tank??


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[Ant-t]

My sensor screws into a moulded aperture which is part of the tank, not sure how you can replicate that if you want to add a sensor

[Smcknighty]

Found this on Samba

http://www.thesamba.com/vw/forum/viewto ... 80&start=0" onclick="window.open(this.href);return false;



The electronics of the circuit board inside the temp gauge will react to an extremely short duration anomaly in the voltage that you couldn't see with a meter. I don't feel like going into a super detailed explaination of the circuit board right now but here is some. When you turn on the key 12 volt power is sent to the cluster, is stepped down to 10 volts by the voltage stabilizer, and then fed to the temp gauge module. The temp gauge internal circuit board has a capacitor on it. The capacitor takes time to fill up to capacity. Before it is full the led blinks. When it gets filled, the blinking stops. There is a current limiting resistor in the power feed to the capacitor. This resistor makes the capacitor fill up slower than it would without the limiting resistor. While the capacitor is filling the led blinks. The temp sender works by providing a leak for the power in the temp gauge to go to ground. The hotter the temp sender the faster the leak. (that is also what the gauge needle shows, the current flowing through the sender to ground, the temp gauge is a current meter) When the engine is too hot the temp sender drains the capacitor faster than the resistor will allow it to fill. That makes the led blink again when the engine is too hot. While the capacitor can drain in an instant it fills back up slowly because the limiting resistor restricts the fill rate. The led blinks until the capacitor it is full again. So just a tiny blip in the power feed can cause multiple blinks while the capacitor fills back up through the limiting resistor.

When the engine is cold the temp sender does not drain as much current from the gauge capacitor. So it takes more of a voltage anomaly to cause the false blinking when the engine is cold. Once the engine is warmed up there is always more current flowing from the gauge to the temp sender. That higher constant drain when engine is up to temp means a smaller interruption in the filling of the capacitor will cause the blinking with a warm engine than a cold engine.

(as a reminder, this blinking function has nothing directly to do with the coolant tank level sensor. That sensor goes to a relay and the relay connects to the gauge. The relay then provides an additional drain of the capacitor whenever the level sensor triggers the relay to do so. If you pull the coolant relay you remove the coolant level sensor system from any involvement in the gauge led behavior. This is a useful test to determine where the a false blinking is coming from. In this case this test has already been done and showed that the blinking was not from the coolant level warning system)


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[Smcknighty]

My money is on the relay already being gone


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[Smcknighty]

Tapatalk didn't update those bits before I posted my replies. Marlinowner I reckon your right, no relay. Also as there's no screw in option on this tank I'm back to waiting and getting a new tank plus pipework at some point in the future. It would be a nice feature to add as all my overheating woes have been proceeded by low coolant, also I'm sure the overflow tank piece doesn't work with the old style tank


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[Smcknighty]

Sorted http://www.farnell.com/datasheets/81468.pdf" onclick="window.open(this.href);return false; pressure rated to 4 bar 110 degrees max temperature. Might give this a shot. I saw similar stuff on a landrover forum but with a side mounted switch. Top mounted seems more right


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[a1winchester]

Found this on Samba

http://www.thesamba.com/vw/forum/viewto ... 80&start=0" onclick="window.open(this.href);return false;



The electronics of the circuit board inside the temp gauge will react to an extremely short duration anomaly in the voltage that you couldn't see with a meter. I don't feel like going into a super detailed explaination of the circuit board right now but here is some. When you turn on the key 12 volt power is sent to the cluster, is stepped down to 10 volts by the voltage stabilizer, and then fed to the temp gauge module. The temp gauge internal circuit board has a capacitor on it. The capacitor takes time to fill up to capacity. Before it is full the led blinks. When it gets filled, the blinking stops. There is a current limiting resistor in the power feed to the capacitor. This resistor makes the capacitor fill up slower than it would without the limiting resistor. While the capacitor is filling the led blinks. The temp sender works by providing a leak for the power in the temp gauge to go to ground. The hotter the temp sender the faster the leak. (that is also what the gauge needle shows, the current flowing through the sender to ground, the temp gauge is a current meter) When the engine is too hot the temp sender drains the capacitor faster than the resistor will allow it to fill. That makes the led blink again when the engine is too hot. While the capacitor can drain in an instant it fills back up slowly because the limiting resistor restricts the fill rate. The led blinks until the capacitor it is full again. So just a tiny blip in the power feed can cause multiple blinks while the capacitor fills back up through the limiting resistor.

When the engine is cold the temp sender does not drain as much current from the gauge capacitor. So it takes more of a voltage anomaly to cause the false blinking when the engine is cold. Once the engine is warmed up there is always more current flowing from the gauge to the temp sender. That higher constant drain when engine is up to temp means a smaller interruption in the filling of the capacitor will cause the blinking with a warm engine than a cold engine.

(as a reminder, this blinking function has nothing directly to do with the coolant tank level sensor. That sensor goes to a relay and the relay connects to the gauge. The relay then provides an additional drain of the capacitor whenever the level sensor triggers the relay to do so. If you pull the coolant relay you remove the coolant level sensor system from any involvement in the gauge led behavior. This is a useful test to determine where the a false blinking is coming from. In this case this test has already been done and showed that the blinking was not from the coolant level warning system)

That's a really interesting, clear explanation and deserves a place on the WIKI in my opinion

[kit]

This goes some way to explain why I have never had a glow plug light but the guy I bought it from (15 years ago) said to wait until the red light stops flashing and then the glow plugs are ready, this has been very effective all the time I have owned it but I never knew why?

[Aspetc]

I second that that should be in the wiki - I've been troubleshooting my temp gauge today and this explanation is tremendously helpful to understand what's going on. Thank you!

[trundletruc]

The water light flashes on my van if the van has not been used for some time. e.g. over the winter. First time of starting it is okay but the next few times it will flash for ages, sometimes never going out! In the Summer when we are using the van a lot it behaves fine. Keep on meaning to sort it out but by the time I get round to it, it's working again.

When working properly it works from the level sensor and the temperature gauge. Take off the wire on the temperature sensor and you will see? Complicated bit of electronics, too complicated for me. I think there is something about fixing it somewhere on this site?