Red temperture warning light with a twist

[newkid]

Hoping someone can help here.

As by some of my previous post for help, Ive basically changed all my mums cooling system, new radiator, fan switch, stainless water pipes, water pump, thermostat and thermostat housing. Before all this the red light would flash constantly but never over heat, main reason it was all changed is radiator had a slight leak and the main water pipes also slightly leaked. Ever since everything has been fitted the light never does the self check, every now and then from cold start it will go on and off faintly within half a second. Were hoping someone has some knowledge on how to get the light to work again as its obviously an important part of the cooling system.

Thanks.

[MidLifeCrisis]

If the coolant temp gauge light isn't doing the 'self check' flash then its one of;
1) The gauge isn't getting 10V from the voltage regulator in the dash gauge cluster.
2) The gauge isn't getting a good ground connection.
3) The gauge itself is faulty/broken/not working

Does the gauge needle more/work correctly?

[newkid]

Hi

The gauge moves correctly, goes past the red light location to about 1 o'clock but then settle back to just past the centre location and stays there even on a long drive.

[ChrisTriple]

Sorry to hijack this thread . Have the red light flashy problem, I've cleaned all the earths fitted a new probe in the water tank, swapped the relay 43 (or42 was it) for a known good one. I've even tried a known good dash pod, yet I still can't sort it.

How do I check for the 10volts?

Anything else I can try?

[Smcknighty]

This is my thread when I replaced mine - has the part no's

https://club8090.co.uk/forum/viewtopic.p ... 6#p7796800" onclick="window.open(this.href);return false;

I think some of the links have photos, you can test it with a multimeter - you can see it and test it when taking the cover off the dash clocks.

This was what I found when testing mine - slowed me down as I was looking for a three legged thing. This is an after market upgrade I think..

[MidLifeCrisis]

Hi

The gauge moves correctly, goes past the red light location to about 1 o'clock but then settle back to just past the centre location and stays there even on a long drive.

newkid - if you are confident that the needle is working correctly then the only real source of the problem can be the light and/or the light circuitry in the gauge (which tends to end up being that the capacitor is not working in the light circuitry - the capacitor is the component that is responsible for flashing the LED when you first turn on the ignition); Does the LED flash if you pull the plug out of the coolant level sensor?

Sorry to hijack this thread . Have the red light flashy problem, I've cleaned all the earths fitted a new probe in the water tank, swapped the relay 43 (or42 was it) for a known good one. I've even tried a known good dash pod, yet I still can't sort it.
How do I check for the 10volts?
Anything else I can try?

ChrisTriple - What's the actual problem that you are seeing?
What happened when you tried a known good dash?
P.S. Maybe start a new thread!

[newkid]

Hi

The gauge moves correctly, goes past the red light location to about 1 o'clock but then settle back to just past the centre location and stays there even on a long drive.

newkid - if you are confident that the needle is working correctly then the only real source of the problem can be the light and/or the light circuitry in the gauge (which tends to end up being that the capacitor is not working in the light circuitry - the capacitor is the component that is responsible for flashing the LED when you first turn on the ignition); Does the LED flash if you pull the plug out of the coolant level sensor?

Sorry to hijack this thread . Have the red light flashy problem, I've cleaned all the earths fitted a new probe in the water tank, swapped the relay 43 (or42 was it) for a known good one. I've even tried a known good dash pod, yet I still can't sort it.
How do I check for the 10volts?
Anything else I can try?

ChrisTriple - What's the actual problem that you are seeing?
What happened when you tried a known good dash?
P.S. Maybe start a new thread!

Hey midlife, I'm positive the needle is working correctly, just the led. Ill check the flash when i unplug the coolant sensor today and report back. Btw when I said 1'oclock then drops back, i meant 1 o'clock as if the temperature needle section was a mini clock. 1 o'clock on the time clock area would mean we were overheating, i really need to think how I word things better.

[ChrisTriple]

I've started my own thread.

[newkid]

Little update, unplugged the water level plug from the sensor and it made no difference to the temperature reading or the red light, when I pulled the wires apart with it unplugged the temperature gauge shot right up to maximum and the red light started flashing. I'm presuming this means the plug is damaged inside making it bridge the connection fooling the sensor?. What I have done is a temp measure is cut the plug off and hardwired them direct to the sensor. With both plugged in the temperature gauge is reading correctly and no flashing red light, unplug either wire and the gauge shoots back up to maximum and light flashes.

Quick question tho, with the temp solution, should the red light flash each time you turn the ignition on or only from cold start? Reason I ask is with the temp solution the red light doesn't flash when ignition is turned on but the engine was still hot after a long drive.

[MidLifeCrisis]

Little update, unplugged the water level plug from the sensor and it made no difference to the temperature reading or the red light, when I pulled the wires apart with it unplugged the temperature gauge shot right up to maximum and the red light started flashing. I'm presuming this means the plug is damaged inside making it bridge the connection fooling the sensor?. What I have done is a temp measure is cut the plug off and hardwired them direct to the sensor. With both plugged in the temperature gauge is reading correctly and no flashing red light, unplug either wire and the gauge shoots back up to maximum and light flashes.

That is really odd behaviour. Correct behaviour is that when the water level sensor plug is disconnected the red light should flash but the needle should stay where it was (i.e. not go to maximum).
Can you check whether you have the correct water level sensor relay (should have a 42 or 43 printed on it) - location depends on the van year I think - mine is mounted above the fuse panel thingy behind the glovebox - you'll need to take the glovebox out and then unscrew the fuse panel mounts to get a look at it. If you have the newer fuses (blades) then I think it might be mounted on the fuse panel itself.
And just to confirm that we are talking about the same thing - the level sensor is the one mounted in the header tank that holds the coolant?

Quick question tho, with the temp solution, should the red light flash each time you turn the ignition on or only from cold start? Reason I ask is with the temp solution the red light doesn't flash when ignition is turned on but the engine was still hot after a long drive.

Yes - the light should flash whenever you turn the ignition on - it is not dependent on the engine temp.

[newkid]

Relay is numbered 43, its above all the earth crowns. Van is a 84 1.6d left hand drive. Yes its a two pronged sensor on the header tank next to the battery.

[newkid]

Double checked whats happening, the 2 relays above the earth crowns are 43 and 24. When everything is connected and you turn the ignition on, the temperature gauge reads as it should (if from cold start reads minimum, straight after a drive inline with the center of the red led and if been sitting a while reads were the current temperature has dropped to), but no flashing red light. If i unplug either wire on the coolant sensor (the one in the engine bay), the red light starts flashing and the gauge goes straight up to maximum.

[MidLifeCrisis]

If i unplug either wire on the coolant sensor (the one in the engine bay), the red light starts flashing and the gauge goes straight up to maximum.

You mean the coolant level sensor right? (not the coolant temperature sensor)
If so then that is strange behaviour (the needle shouldn't go to max) and might indicate that the 43 relay is not working as it should.
Can you get hold of a donor 43 relay to test whether that fixes it?

[newkid]

If i unplug either wire on the coolant sensor (the one in the engine bay), the red light starts flashing and the gauge goes straight up to maximum.

You mean the coolant level sensor right? (not the coolant temperature sensor)
If so then that is strange behaviour (the needle shouldn't go to max) and might indicate that the 43 relay is not working as it should.
Can you get hold of a donor 43 relay to test whether that fixes it?

Sorry, yes the level sensor (that's the one on the header tank with 2 wires and looks like 2 long prongs when removed?) if so that was also replaced. Ill need to try find a 43 relay unless anyone has one they can sell me?

This is the one I unplug http://www.justkampers.com/vw-t25-parts ... -1992.html" onclick="window.open(this.href);return false;

Cheers for your help on this its appreciated.

[MidLifeCrisis]

FYI - here's a little picture of how the whole coolant gauge system works.
(would welcome any comments as to whether there are any errors?)



Might be useful in your diagnosis.