Club 80-90 Forums

I went and got the van from the unit where it's currently being stored (builders and their bloody scaffolding means I can't get my van even on the drive, let alone in the garage) and brought it home on Friday.
As I expected, the blinky red light was well, blinky.
I've got the new coolant level sender to fit, but couldn't do it on Saturday as I was travelling to London with football.
I drove down to meet the coach and there it was, blinky blinky.

Got back around 9pm and drove home from the club, and guess what? No blinky!!!

Got up at 7 and went to the Queen Square Breakfast Club meet near Bristol, which meant 20 miles up the M5. Still no blinky.

The eldest wallet drainer, aka child, had a match this afternoon and I chose to take the van again. Traffic was pants and was second to third to second to third up the M5 a junction, and still no blinky!

I think I will change the sensor anyway, but just thought it a bit odd that the issue has seemed to disappear.

There is a third possible cause for the led to flash, which I would say you had and that is oxidation of the terminals...Ooo! Matron!

By removing the wires and putting them back on the terminals you have remade the electrical connection and so the circuit now works.

This is my first port of call if the fluid level looks ok, clean up the spade terminal with a bit of wet n dry and try and clean inside the
push on half too.

Regards.

I'm more thinking that the little air pockets that you have had have now burped their way round the system.

Leave the sender alone and see watch the water levels stay constant when cold

Hi Folks.

I'm resurrecting this thread as I have been using the bad weather to work on my coolant circuit using the Wiki article as a guide. I have had the PCB to the LED connection disconnected on mt T25 since I bought it. The gauge itself works fine but I need to keep a close eye on it as the light will not flash if I drop coolant. Anyway, I bought a replacement 42 relay and did continuity checks across all the entire circuit. All seems fine except the resistance seems high across the coolant sensor when immersed in coolant. I am reading about 1.3 MOhms.

Does anyone know (roughly) what the correct resistance range is?

Tie a bit of string or use a cable tie and immerse the sender in a pan of cold water. Heat it up and measure the resistance - the resistance should be around 100ohms as the pot nears boiling point. The value of 100ohms is the gauge sitting slightly left of the coolant led.

Apologies Angelo, I'm talking about the coolant level sensor rather than the temperature sender. The temperature sender is reading about 1.1 kOhms when cool whereas the level sensor is reading 1.3 MOhms (i.e. >1000 times the resistance). I have a new level sensor on order and will report back when I measure the resistance across both the old and the new.

I had this recently, I had changed the low level sensor but still flashing, I checked the wiring to the sensor but still no joy. I consulted the wiki on here and it turns out to have been a bad connection on either the earth crown,relay or connection to instrument panel ( next to brake fluid reservoir)

Ciaraneng wrote:Apologies Angelo, I'm talking about the coolant level sensor rather than the temperature sender. The temperature sender is reading about 1.1 kOhms when cool whereas the level sensor is reading 1.3 MOhms (i.e. >1000 times the resistance). I have a new level sensor on order and will report back when I measure the resistance across both the old and the new.

Essentially the level sensor is just two probes stuck in the coolant and you are measuring the resistance of the coolant between the two probes - so its always going to have a pretty high resistance (but less than it would have if there was only air between the probes!)
This is why this circuit is particularly sensitive to bad earths as it is trying to measure a tiny voltage coming back from the probes.

I've installed a new probe and have 1.8MOhms between the probes so the original is probably fine. I've removed Relay 42 and my LED is still flashing. I'll check the earth again but I suspect I may be dealing with a broken gauge.

Ciaraneng wrote:I've installed a new probe and have 1.8MOhms between the probes so the original is probably fine. I've removed Relay 42 and my LED is still flashing. I'll check the earth again but I suspect I may be dealing with a broken gauge.

If you have removed relay 42 and the LED is still flashing (and the needle is not in the 'hot' position) then as you suspected the gauge is probably broken. When the gauge is first powered on, the LED flashes a few times (as a sort of self check), this is done by charging a capacitor (the LED flashes until the capacitor is charged); if the capacitor is broken, then it never charges and the LED keeps flashing - I think that there is info in the Wiki about changing out the cap - its not impossible but it is fiddly and involves soldering in a new cap in a pretty tight spot inside the gauge.

MidLifeCrisis wrote:

Ciaraneng wrote:I've installed a new probe and have 1.8MOhms between the probes so the original is probably fine. I've removed Relay 42 and my LED is still flashing. I'll check the earth again but I suspect I may be dealing with a broken gauge.

If you have removed relay 42 and the LED is still flashing (and the needle is not in the 'hot' position) then as you suspected the gauge is probably broken. When the gauge is first powered on, the LED flashes a few times (as a sort of self check), this is done by charging a capacitor (the LED flashes until the capacitor is charged); if the capacitor is broken, then it never charges and the LED keeps flashing - I think that there is info in the Wiki about changing out the cap - its not impossible but it is fiddly and involves soldering in a new cap in a pretty tight spot inside the gauge.

Thanks MLC. I've got two gauges. I'll try both and if both continue flashing I'll try the capacitor replacement on one.

I think the instructions I saw previously for replacing the capacitor are here: http://www.vanagonauts.com/Warning-Light-Fix241.htm but the link no longer seems to work. Does anyone have an alternative link or know what size the capacitor is? I have a selection of capacitors and want to check I have the right one before I start drilling out rivets.

Ciaraneng wrote:I think the instructions I saw previously for replacing the capacitor are here: http://www.vanagonauts.com/Warning-Light-Fix241.htm but the link no longer seems to work. Does anyone have an alternative link or know what size the capacitor is? I have a selection of capacitors and want to check I have the right one before I start drilling out rivets.

The below link suggests it is a 10 millifarad 16v. tantalum capacitors

https://www.thesamba.com/vw/forum/viewt ... p?t=168239

Some pics of when I did mine - apologies for poor quality but might be helpful;

1) Drill out one of the rivets so that the gauge can be swung out of the way;



2) This pic shows the cap that you are trying to remove - but this view is the opposite of the side that you will see when you open the gauge up - but might help to orient yourself



3) This pic shows the two solder joints that you'll need to desolder to pull the cap out from below it (if that makes sense)



4) Last pic showing the new capacitor soldered onto the 'accessible' side of the board

Thanks MLC, early gauges seem to be slightly different in construction but I’ll give it a try.

.


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Ciaraneng wrote:Thanks MLC, early gauges seem to be slightly different in construction but I’ll give it a try.

My pics are of an 'early' gauge (i.e. from a non-rev counter display) - although mine seems to have rivets - looks like yours may just have bent tabs holding the 'display' on so might even be a bit easier (?)