Coolant temperature gauge - flashing red light+needle swing

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Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

Not sure if anyone can shed anylight on this.
One of the annoying things I find about my coolant temperature gauge is when the header tank get's low, I get the flashing light (I expect that), but along with that, the needle then violently starts swings up to maximum, though the engine is not overheating, as the fans haven't come on.
When it swings up like that, it S***ts the life out of me, I expect the flashing red light, as the warning. However, is the needle swing part of the automatic process, I feel it's providing me false information in regards to the actual temperature, I heed & respect the warning (red light), but want to know is the needle swing normal hand in hand?
Holdsworth Villa2 1983 1.9 DG, 4 Speed, LPG & Petrol+underslung leisure tank

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

It all depends on the control module that is fitted to your van. Very early ones behaved as your does. Later ones only flash the LED. Want to know more, it's all on Samba


https://www.thesamba.com/vw/forum/viewt ... &start=123
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

Cheers ok, so it is a hand in hand process then.
I was wondering if I could wire up a operation light, when the fans come on ( sometimes you can hear them, sometimes not), which might give me a indication of actual overheating, if the needle did this swing again?
(And yes I know prevention is better than cure, by making sure the header doesn't get low), I am working on the leak currently, as there is one).
Holdsworth Villa2 1983 1.9 DG, 4 Speed, LPG & Petrol+underslung leisure tank

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

No, change to the later module and the needle won't go full scale if you are just low on coolant.

If you are overheating, the needle will already be in the hot position and the LED comes on to tell you you've not been watching your gauges

Brickwerks have the latest ones in stock
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

937carrera wrote:No, change to the later module and the needle won't go full scale if you are just low on coolant.

If you are overheating, the needle will already be in the hot position and the LED comes on to tell you you've not been watching your gauges

Brickwerks have the latest ones in stock

Is the module a straight swap over?
What are they called on Brickwerks having trouble finding it!
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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »


Oh it's a relay, do I have a slot for that on an early version?
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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

You're replacing a late module 42 for your early tall module 43

Have another read of the Samba thread
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

937carrera wrote:You're replacing a late module 42 for your early tall module 43

Have another read of the Samba thread

OK cheers, I'll have a bash at that tomorrow, as late! :ok
Though, just trying to work out what number relay it is on my early T25 (is it number 3)!
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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

This is my relay board, I assume this 42 relay isn't fitted on my van?
Mine is late 83, did they have a 42 relay?
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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

You have one, it will be a "tall 43" otherise the coolant level LED would not flash.

Do you have a cartridge or blade type fusebox, looks like an cartridge / ceramic to me ?

Can you identify the relays by part number - look at the Samba thread again
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

937carrera wrote:You have one, it will be a "tall 43" otherise the coolant level LED would not flash.

Do you have a cartridge or blade type fusebox, looks like an cartridge / ceramic to me ?

Can you identify the relays by part number - look at the Samba thread again

Ok thanks, I have the ceramic fuses. I know what relay I am looking for but it's not in my box. My relays in the photos left to right, flasher relay, Number 24 not that part number, Headlight relay.
Would it be elsewhere in the vehicle?
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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

It could be. All the references I have found refer to position 3 in a blade fusebox.

I did find an early WBX wiring diagram and that didn't show it integral with the fusebox. I don't have an early WBX so can't go looking. You'll need to have a nosey round the van, find something online or wait for someone who simply knows :)
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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Re: Coolant temperature gauge - flashing red light+needle swing

Post by nesty »

937carrera wrote:It could be. All the references I have found refer to position 3 in a blade fusebox.

I did find an early WBX wiring diagram and that didn't show it integral with the fusebox. I don't have an early WBX so can't go looking. You'll need to have a nosey round the van, find something online or wait for someone who simply knows :)

Thanks for the help appreciated. It's certainly not in the relay box, all of them are for different things, so it's either elsewhere or this early system doesn't have a relay!?
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Re: Coolant temperature gauge - flashing red light+needle swing

Post by 937carrera »

It has one, otherwise the LED wouldn't work.

If you have Bentley it's shown on page 97.56, current track 33-34, though this is of course USA market wiring. Nothing in Haynes
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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