Temperature gauge light.

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garyharbord
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Temperature gauge light.

Post by garyharbord »

My Temperature gauge light is permanently on and only goes off when the Headlights are switched on . I guess its a wiring problem anyone point me in the first point of call.
Thanks. 

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maxstu
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Re: Temperature gauge light.

Post by maxstu »

Hi Gary,

Let's start by having some details of the van/camper.
Age and type of engine will help.

Regards
Stuart
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Mocki
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Re: Temperature gauge light.

Post by Mocki »

we will assume you are not sure how it works ......


The flashing red light in the temp gauge has two functions ....
 1. If the gauge is above 3/4 and it's flashing it means over heating 
 2. If the gauge is below 3/4 and it's flashing , it means low coolant in the header tank. 
  
 If it's say low coolant , and the coolant isn't low then it's an electrical issue , and simple fault diagnostics will need to be employed ! 


so..... 
The T25 coolant warning system is essentially in two parts. The level sender part and the temp sender part. Either of these can cause the LED to flash, but theoretically, only the Temp sender part should influence the gauge needle position. 
  
 Removing Module 43 removes the level sender part of the system whch is useful in diagnosing erroneous LED flashing. Module 43 outputs a sine wave voltage to the level sender, if the amplitude of that sine wave exceeds a threshold value (due to loss of fluid) then module 43 outputs short duration negative pulses every few seconds to trigger the Small circuit in the gauge. These pulses are short duration, low frequency and should not significantly affect the gauge position unless left to do so over a long period of time.
  
 However, module 43 could become faulty and affect the needle position but rare.
  
 The temp sender affects the gauge position and if the resistance falls below a critical threshold then the gauge internal circuit triggers the LED and the needle rises.



Check you have enough coolant , and that the header tank is full to the brim when cold ✔️
Check the connections are clean and connected at the top of the header tank ✔️
Unplug the header tank and bridge the two connections in the plug on the loom , the light should stop flashing 
( you need to turn ignition off and then on again to reset each time you check a step .
Steve
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garyharbord
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Re: Temperature gauge light.

Post by garyharbord »

Thanks for the replies. Its a westy 1.9 DF

So ive ordered a sensor that goes into the Header tank and another single wire sensor that screws into the engine. Both only a few quid so i will replace them both and get back on here to let people know. The thing thats getting me is it goes out when the headlights are on, but stays on when side lights are on, or no lights are on.

If the change of sensors dont work could it be a Dash PCB problem??

Many thanks guys.

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Mocki
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Re: Temperature gauge light.

Post by Mocki »

If your headlights affect it , it’s earth issue. Clean the base and earth for the control module (43) looks like a relay up above the fuse box . Clean the earth crown . 

importantly, don’t change more than one thing at once , do one, then check , then move onto the next .... 
Steve
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MidLifeCrisis
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Re: Temperature gauge light.

Post by MidLifeCrisis »

Is it high-beam that makes the temp light go off or just 'normal' low-beam?
If you have high-beam on - does the blue 'high-beam' light come on?
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AngeloEvs
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Re: Temperature gauge light.

Post by AngeloEvs »

As already advised, remove module 43 (or may be marked 42). This will isolate the gauge from a number of possible causes including earth problems at the crown cluster. If the gauge led behaves normally with 43 removed then, as Mocki suggested, inspect the earth crown as it shares the connections with the headlights which can overheat with age and affect the other connections one of which is the earth for the module itself. If the temp led continues to be a problem with 43 removed and the headlights on then it may well be an issue at the dash. But, as advised, check one thing at a time.
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garyharbord
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Re: Temperature gauge light.

Post by garyharbord »

Thanks people you really are a wealth of knowledge. so ive changed the coolant sensor and temperature sensor independently and still getting the flashing red light. It does go out on headlights but comes back on on main beam. I will check the 43 module as advised and clean it up. I will let you know.
Many thanks

Gary.

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