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Temperature/fan not working.

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Temperature/fan not working.

Postby Cooltywyn » Mon May 21, 2018 7:12 pm

Hi all bit of help please?
I have a 2003 mk6 2.0 TD fwd. I've had it around 6mths and the temperature gauge hasn't worked. When you turn the ignition on it goes down & stays there. The heater works great. Now the weather is getting warmer I've noticed that the fan doesn't kick in, so have started to investigate the problem. I have checked the temperature sender in the head & it looks new, so I bridge the connection to simulate a hot engine & still the gauge goes down & the fan doesn't come on. I've also checked all fuses and all ok.
Any help or advice please?

Roy
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Re: Temperature/fan not working.

Postby wojciech » Mon May 21, 2018 10:19 pm

Temperature sender in the head (CHT) it is termistor - semiconductor devices (resistor NTC). Gauge gets signal from analog-to-digital converter, controlled by PCM. Your test cannot succeed. CHT sensor works in two rangers, switched by PCM. If you bridge his circuit, PCM shouild assume temperature 132 deg.C - engine is stopped and start is impossible. Did you try start engine with bridge CHT cables?
In many cases sender works ok in one range, but in second is kaput. Generaly it likes to go bad.
Opposite situation - if CHT circuit is opened, PCM assume temperature 120 deg. C, fun works with full power, injection dose is reduced. It is not your case.


About fan - usually it works only in very warm weather and not during driving - mostly in town in traffic jam (or - of course - if AC is on (then are two fans in FWD)).

So - your CHT sensor is damaged - I think.
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Re: Temperature/fan not working.

Postby Cooltywyn » Sun May 27, 2018 7:48 pm

Well today after lot of bad language & sore knuckles I've changed the sender unit (what a stupid place to put it).
Guess what, still exactly the same?
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Re: Temperature/fan not working.

Postby ABA » Sun May 27, 2018 8:44 pm

you mite find its down to dry solder joints on the back of the clocks if you take them out its worth while to run solder over all the contacks as sooner or later they will all go down common fault with mk 6 transits had to do mine last year
not sure about the fan though
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Re: Temperature/fan not working.

Postby Altransit » Sun May 27, 2018 8:54 pm

I can't remember the engine fan on my Mk6 ever kicking in, even in hot weather, so maybe it's just not hot enough to be working :idea:
May be worth putting 12v on the fan contact wires to see if it actually runs, and if there's one fitted, check the fan controller attached to the rad casing :)
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Re: Temperature/fan not working.

Postby Cooltywyn » Sun May 27, 2018 9:42 pm

Thanks for your suggestions, will try both of them are what happens.

Roy
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Re: Temperature/fan not working.

Postby Brains_transit » Sun May 27, 2018 10:27 pm

Check the engine bay fuse box there's 2 fuses for the cooling fan and unplugging the sensor on the engine and running it makes the fan come on as it thinks it's needed but won't shut the engine down
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Re: Temperature/fan not working.

Postby Cooltywyn » Mon May 28, 2018 9:53 am

Thanks I've checked the fuse and all ok, will try your suggestion to see if fan comes on.

Roy
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Re: Temperature/fan not working.

Postby wojciech » Mon May 28, 2018 8:04 pm

Cooltywyn wrote:Thanks I've checked the fuse and all ok, will try your suggestion to see if fan comes on.

Roy

But you have two problems - one doubtful with fan, second undoubted with temperature gauge.

ABA wrote:you mite find its down to dry solder joints on the back of the clocks
Try do what ABA advise - do it, using clean cloth and methylated alcohol. After longer time on solder joints comes characteristic eruptions (tin oxide) and they makes additional connections on circuit board. It is good idea...
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Re: Temperature/fan not working.

Postby Cooltywyn » Sat Jun 02, 2018 4:09 pm

Well today I've stripped out the dashboard clocks, checking all the solder joints and cleaning all contacts,, STILL TEMPERATURE GAUGE DOESN'T WORK!!!!
Strange thing is while the instrument panel was out in the sun the gauge went up but as soon as I reconnected it it went down past the bottom again?

Stuck with what to do next?
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Re: Temperature/fan not working.

Postby wojciech » Sun Jun 03, 2018 11:14 am

The easy way out - connect your clocks to the other van (to his plug). I assume, that CHT sensor and his wires are ok.

If you want - take multimeter and check voltage on CHT pins. Look for picture - on the begining (with cold engine) it should be around +3V and shoud go down to +0,5V (+78C deg), and then voltage must jump up to +3,5V. This is very important moment - without this jump up to 3,5V and if CHT sensor is in 100% ok - it is suggestion PCM is broken. If voltage drops to 0,5V, PCM should switch on resistor "pull up" and voltage must jump up.

A - digital signals (after PCM A/D converter)
B - voltage on CHT sensor
C - temperature (Celsius)
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Re: Temperature/fan not working.

Postby ABA » Sun Jun 03, 2018 1:12 pm

Cooltywyn wrote:Well today I've stripped out the dashboard clocks, checking all the solder joints and cleaning all contacts,, STILL TEMPERATURE GAUGE DOESN'T WORK!!!!
Strange thing is while the instrument panel was out in the sun the gauge went up but as soon as I reconnected it it went down past the bottom again?

Stuck with what to do next?

did you resolder the joints not just clean them
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Re: Temperature/fan not working.

Postby Cooltywyn » Fri Jun 08, 2018 10:35 pm

A friend of mine who is a tv engineer checked them all and said they were all ok.
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