Coolant Red Flashing Light

[pfield69]

A common fault by what I've read on here but mine has just started to flash.

I have followed through this thread
http://archive.club8090.co.uk/viewtopic ... 08e1f1bb38" onclick="window.open(this.href);return false;

But still no luck.

Historically my temp gauge has always read low, just on the end of the solid white part of the gauge. It did work as it did get hotter in traffic & when it spat the water out (hopefully this is fixed). Now it reads the cold side of this solid line and doesn't move. I discovered that pin #5 on the flexicircuit was broken. I believe this is a 12v line to the back of the clock. I have jumped this direct to the contact on the back of the clock. All other multi plug connections appear to have good connections.

I have tried jumping the rear coolant sensor plug and checked continuity from the connection box in the engine bay to earth (blue/green wire).

Pin #6/4 is connected to the capacitor on the flexicircuit and has about 3v??
Resistance across the level sensor is about 300k?
I removed the 'relay' #43 as described in the above thread and it made no difference.

Is it likely to be a temp sensor error as mine was reading so low before?

Any help is much appreciated.

(btw wish me luck with MoT tomorrow)

[MidLifeCrisis]

Have a look at this thread over on 'Electrical and Intrumentation' - see if any of the info on there helps.
https://club8090.co.uk/forum/viewtopic.php?f=39&t=129227

[croc]

Hi
Had a similar problem last year, not really sorted yet but I have found some quirky aspects to this! All through this the temp needle showed normal.
I went through all the recommended fixes - cleaned probes in expansion tank, checked connections, had dash off and did earths crowns etc etc ...
None really had any effect.

I renewed the coolant from more than 2 years old blue to new red 5 year coolant after several flushes with radiator hoses off.
This seemed to cure it - temporarily!

Have since found if I turn key on then wait about 5 seconds before engaging starter - ie the normal self-test time - the LED goes off when starter is then engaged and it will stay off while running ???
This was more pronounced when engine hot. Sometimes first cold start without waiting the LED would then go out as it should.

I have no idea what fault this indicates!
And I am not sure if the LED operates correctly on coolant loss. This would be really nice to know as the LED has saved my engine several time previously when blowing head seals lost the coolant.

I know how frustrating this can be so you have my sympathies! But try the pause before starting engine and if it works for you perhaps you can post an update on the cause?

Good luck!
BTW good luck with MOT!
Jon

[croc]

PS
I had used K-Seal last yearr but several months previous to the LED problem so not sure if there is a connection between these?

The leak sealer does contain copper flakes but cleaning the sensor probes didn't have any effect, so ??? still a mystery!

[pfield69]

I have k seal too, although I don't think this is an issue as if you remove the controller (relay #43) the red light still flashes.

I'm going to check temp sensor And v-reg.

It would be nice if someone has a picture with the connections marked up.

[pfield69]

My checks so far.

Voltage reg = 9.9v
continuity checked ok from red/yellow cable #6 to gauge terminal nut
continuity checked 300kohms to earth from #5 of relay34 or 0ohms when coolant level plug jumped with wire.
Good earth on pin#3

What resistance should be on the temp sender?
Relay 43 removed still makes light flash.

[MidLifeCrisis]

Ok - so if you have removed the relay and the led still flashes then you can discount the coolant level sensor and the wiring from it to the relay as the source of the problem.

What happens if you disconnect the wire to the temp sensor (you can do this at the sensor on the engine)?
Does the led still flash?
Then try grounding that wire (i.e. touch it to a metal bit of the engine) - what does the gauge needle do, what does the led do?

(FYI - from your earlier comments - pin 5 on my dash connector is a ground connection - not a connection to the clock; what year van is it as I think that there are different pinouts on that connector dependent on age?)

[pfield69]

duplicate deleted

[pfield69]

Thanks. My van is a 1989 1.9 DG
connections on the rear of instrument panel are as 90.18 in Bentley where #3 ground #5 clock #6 coolant. #4 is marked as open but is actually a loop round from #6.

I'm struggling to get sensor plug of temp sensor, is there a lock or release somewhere as I can't see it?

[pfield69]

Ok, found the metal lock on connector.

Disconnect temp sender, light still flashes.
Earthing wire = smokey hot wire!!!

12v on sender positive, 0Ω on return to earth.

[MidLifeCrisis]

Ok, found the metal lock on connector.

Disconnect temp sender, light still flashes.
Earthing wire = smokey hot wire!!!

12v on sender positive, 0Ω on return to earth.

Errrr ... that doesn't sound right.
There should only be one wire going to the sensor.
Are you sure you had the right sensor?? On mine the sensor is on the thermostat housing.

[pfield69]

I have a 2 pin temp sender. Also shows 2 pin in Bentley (24.32, 19.8 ).

Situated on thermostat housing. I'm not sure how to read the resistance diagram though (24.32).
Also I wasn't expecting the smoke to be let out. I will get some variable resistors to see it these will help get a reading given resistance is +300kΩ on sensor

[MidLifeCrisis]

What engine/year van do you have?

That temp sensor that you mentioned in Bentley at 24.32 is for injection control.
If you look at the pic on 19.8 - the sensor you want is the one marked 'Temperature Gauge Sender' (not the one marked 'Temperature Sensor').
But will prob depend a lot on your engine - mine is a old style df/dg - I only have a single sensor on the thermostat housing which is the Temperature Gauge Sender. Yours may be different so age/engine type will be helpful.

Also, pics would really help of the location of the sensor in your engine ?

[pfield69]

Engine is a 19 DG.

Looking again, I have 2 sensors on the thermostat housing. The other one is forward facing, unfortunately I can't get an angle to get a picture.
(I also don't know how to upload pictures here

[MidLifeCrisis]

Here's the temp sensor on mine - signal yellow/red wire running to it (the pic is taken from the back of the van looking down) You may have the newer style thermostat that is located differently (but on theory the wire colour should be the same - but strange things happen with vw wiring colours?!?)