temp light flashing again

[Shaundon]

My temperature warning light on the gauge has started flashing again.

Happens when I accelerate hard and goes out if I ease of the accelerator.

needle seems to remain the same throughout, just slightly to left of flashing light!

ive removed the relay 43 and it still happens so dont think its in that circuit at all.

i took some readings from the temperature sensor at the back

When cold it reads 1417 ohms and drops 9.74V across it
When upto temperature it reads 116 ohms and drops 6.63v across it

does this sound normal?

anyone know why it would flash when accelerating hard?

S.

[AdrianC]

First, stupid question... Is there enough coolant in both reservoirs?

If it's genuinely a false warning, then it's probably a loose wire that's flapping about.

[Shaundon]

Yeah - checked the water levels in both header and expansion tank and are fine (header full to brim, expansion has plenty in it).

Might try wiring up a new wire to the dash to see if it clears it.

S.

[VWGeoff]

Sorry to nick the topic I have similar problem here. My problem started about a week ago. It sprung a leak from a lose jubilee clip on new radiator on the offside. I tightened that and bled it. Now I`ve got a flashing temperture gauge LED. I`ve bridged wire on expansion header tank and it still flashes? And yes Matrix is getting warm, so is rad. I`ve been checking water and oil levels daily without any drop in either. The reason why I said either was I`ve just stopped an oil LED flashing too about an hour ago. When I found wires to be on wrong oil sensors on my AAZ.

[VWGeoff]

Let us know how you get on?

Yeah - checked the water levels in both header and expansion tank and are fine (header full to brim, expansion has plenty in it).

Might try wiring up a new wire to the dash to see if it clears it.

S.

[Shaundon]

Arrrgggh

So with new cable connected from thermo sensor in the engine bay to the dash (temporarily wired through van) I did a thorough road test and couldn't get it to flash.

Swapped back to the original cable in the loom and tried again and it started happening almost immediately that i revved her up.

So i'm thinking the cable must be shorting somewhere between the sensor and the dash under vibration of the revs causing the gauge to flash.

But - I then tried the new cable with the old cable still connected at the dash end so both cables are running the length of the van but only the new cable is connected to the sensor(old cable left tied back in engine bay). Thinking that if the old cable is shorting it will short the new cable too as they are both connected together at the dash end. But for the life of me couldnt get it to flash with both cables like this.

Swapped back to just old cable and it flashes straight away under high revs.

Any ideas anyone?

[clift_d]

Somebody will come in and correct me if I'm wrong but I'm guessing the coolant level sender acts as a variable resistor that has a higher resistance when coolant is low than when it is full.

Therefore if your old sender cable is fraying/ shorting then it's resistance is higher than the new cable and so it gives a false high resistance reading to the gauge which interprets this as a low coolant level.

In this case, connecting the two together at the gauge end will not really establish anything - the old cable will just not be seen by the gauge or have any effect on the reading, as it won't increase the resistance between the sender and the gauge.

[Shaundon]

The coolant level sensor control unit (number 43)has been removed for the tests. The problem is solely in the coolant temperature sensor circuit in my case.

[VWGeoff]

Is your van an early type with ceramic fuses or later with blade fuses. As I cant find a relay on mine marked 43? Only 21 relay and another with no number 43 that I can see.

The coolant level sensor control unit (number 43)has been removed for the tests. The problem is solely in the coolant temperature sensor circuit in my case.

[Shaundon]

mines early WBX (1984) LHD

the lscu no 43 (not really a relay but looks like one, sometimes its no 42 i believe ) is mounted on the bodywork A pilar to the left of the fusebox under the dash on mine (probably right side on RHD)

check out this link if u haven't already
https://club8090.co.uk/wiki/Co ... ht_on_dash

definitely worth removing this when its flashing to see if it goes out - if it does then its in the level sender circuit , if not then the problem is in the temperature sensor circuit.

I have a spare no 43 you could try if it is in that circuit
where abouts are u located?

[VWGeoff]

Thank You Shaundon. Ive found relay now after reading wiki abit. I`ll leave it for now and have a good thorough read through it later. Geoff

[ducce999s]

Have you resetted the level transmitter and the temp-relay? If not, turn off ignition, take off the cables from the transmitter, turn on ignition until the lamp stop flashing. Turn off ignition and reconnect the cables.

[VWGeoff]

Sorry but I haven`t a clue what you mean by level transmitter on my AAZ diesel? Or where it is.

Have you resetted the level transmitter and the temp-relay? If not, turn off ignition, take off the cables from the transmitter, turn on ignition until the lamp stop flashing. Turn off ignition and reconnect the cables.

[ducce999s]

I will try to give a better explanation

Some times it´s necessary to reset the coolant level warning lamp control module or the coolant relay.

To do that you need to disconnect the wiring plug to the coolant level sensor on the expansion tank.



after that, turn on the ignition (dont start the engine), wait until the red lamp has stoped to flash or aprox 30 sec, turn off the ignition and reconnect the wiring plug.

[VWGeoff]

Thanks
I tried what you said below and still not working properly?

I will try to give a better explanation

Some times it´s necessary to reset the coolant level warning lamp control module or the coolant relay.

To do that you need to disconnect the wiring plug to the coolant level sensor on the expansion tank.



after that, turn on the ignition (dont start the engine), wait until the red lamp has stoped to flash or aprox 30 sec, turn off the ignition and reconnect the wiring plug.