Coolant Temperature Gauge

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pugmug
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Coolant Temperature Gauge

Post by pugmug »

1995 Peugeot 405 1.6
Hi All
i've got a recent problem with my temperature gauge, from cold start up the needle is very often stuck in the middle and on reaching normal temperature the needle goes nearly all the way to the right, the coolant is definately running at the correct temperature and the fan cuts in when it should, at other times, the gauge appears to work correctly with the needle hovering around the centre at normal temp.
any ideas?

maybe a related problem
the fan when running will not run on when the ignition is turned off
PowerLee
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Post by PowerLee »

Hi

Check out the BROWN coolent sensor near the thermostat on the cyclinder head.

Does your car have aircon fitted?

Check the terminals in the plug to.

A new sensor from Peugeot is £13 & you need a deep 19mm socket to fit it.

The cooling fans shouldnt run with the igntion off anyway!

Its either a dodgy connection to the sensor, a dodgy sensor or a dodgy connection to the control unit behind the passenger side headlamp.
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pugmug
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Post by pugmug »

Thanks for the pointers PowerLee
the car does have AC but has never worked, probably needs regassing, i can live without that,
my previous '89 405 rad fan did run on after the ignition was turned off, hence the reason i thought this one should
i'll have a delve under the bonnet this weekend
Cheers
PowerLee
Posts: 1260
Joined: 01 May 2004, 19:49
Location: United Kingdom
My Cars: Current - Slightly modified 2016 Pug 308 Puretech 130 Allure
Past:
2003 - 206 GLX TU3JP & 206 SE ET3JP4
1995 - 405 Executive XU10J2
1996 - 406 GLX XU10J4R
1994 - 405 GTX XU10J2
x 1

Post by PowerLee »

Hi

Your 405 with aircon should be running a Bitron set up that controls the cooling fans & the aircon.

The brown temp sensor on the back of the cylinder head tells the bitron unit to turn the cooling fans on & off & also controls the high temp warning & STOP light on the dash.

The system is smart, The brown sensor is actually needed to keep the cooling fans switched OFF!

If the sensor, connection to it or the wiring go faulty the cooling fans will run all the time & the high temp & STOP lights will come on.

Now the blue temp sensor works the temp gauge on the dash, SO you can have the gauge reading normal & also have the 2 warning lights lit up, 2 different sensors you see.

Also you have a green temp sensor that feeds information to the engine ECU.

3 temp sensors in total all stuck in the back of the cylinder head.

The Bitron control unit is located behind the passenger side headlamp, Its well hidden & bolted down, They can suffer from dry solder joints but I would check the brown temp sensor & the connections between the two parts first.

Your previous 1989 405, Did it have a carburettor? These had a modification done by Peugeot to stop the carb overheating after the car was parked up ( The original carbs where awful anyway & most clued up owners stuck a Webber carb conversion kit on )

The mod was if the engine was hot to run the cooling fans for up to 12 minutes to cool the engine down.

To quickly test your aircon turn the igntion on so all the warning lights are on but dont start the engine, set the temp control to cold & press the A/C button in.

Now behind the passenger side headlamp is a black cylinder ( aircon dryer bottle ) with a brown plug attached & 4 wires in it ( pressure safety switch ) Short terminals 1 & 2 together in the brown plug & see if the cooling fans now roar into life.

If they do roar into life then you need at least a re gas but if the system hasn't had gas in it for a while then it will most likely need a new set of seals fitted to.

The 405 aircon system is very good, Keeps you cold in the summer & also de mists your windows in the winter, Once you have had aircon you really grow to like it :wink:

NOTE: DO NOT start the engine with the aircon pressure safety switch bypassed, You WILL ruin the aircon compressor!
Linchpin
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Post by Linchpin »

Apologies for posting in your thread, but Powerlee, is there something like this on the 306 Aircon system?

Mines dead too :(
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Post by Linchpin »

Apologies for posting in your thread, but Powerlee, is there something like this on the 306 Aircon system?

Mines dead too :(
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pugmug
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Post by pugmug »

Thanks PowerLee

Still haven't got around to fixing this yet but changing a sidelight bulb this week, i must have moved some of the wiring under the nearside headlight because the temp gauge has been working fine since, so there's a good chance it's nothing more than a dirty connection.

Will look at the aircon when time permits, are they expensive to regas and where do you go to get it done?

Hope you can get your problem sorted Linchpin
PowerLee
Posts: 1260
Joined: 01 May 2004, 19:49
Location: United Kingdom
My Cars: Current - Slightly modified 2016 Pug 308 Puretech 130 Allure
Past:
2003 - 206 GLX TU3JP & 206 SE ET3JP4
1995 - 405 Executive XU10J2
1996 - 406 GLX XU10J4R
1994 - 405 GTX XU10J2
x 1

Post by PowerLee »

Ah ha, You where in the aera of the nearside headlamp & your odd electrical fault has fixed itself.

The Bitron control unit is located there but I would check the main loom connections first.

Behind the nearside headlamp are 3 large round connectors, grey, brown & black, The main wiring loom passes through these & they do give trouble.

Its another classic design cock up by PSA Peugeot / Citroen, Some french idiot when they where designing the connectors thought it would be a good idea to have a male electrical terminal in one half just touching another male electrical terminal in the other half.

What happens as the car ages the temrinal spread apart, They then start getting hot because resistance has built up & the electrics then start playing up.

You need to twist the locking ring on the middle of the connectors & check all the terminals inside both halfs of all 3 plugs are clean & are touching each other when the plugs are connected.

Shut the alarm system down with the key ( if its still working ) make sure you have the radio code & then disconect the battery before undoing the connectors.

Find a aircon place in yellow pages etc or ask how much the main dealer would charge.

I do warn you now if the aircon system hasnt had gas in for a while it will most likely need new seals fitting before it can be filled with gas!

Aircon systems need to be used at least once a week for 10 minutes minimum to keep the seals in good condition, If you dont use it the seals dry up & the gas then escapes.
Last edited by PowerLee on 02 Feb 2006, 19:13, edited 1 time in total.
PowerLee
Posts: 1260
Joined: 01 May 2004, 19:49
Location: United Kingdom
My Cars: Current - Slightly modified 2016 Pug 308 Puretech 130 Allure
Past:
2003 - 206 GLX TU3JP & 206 SE ET3JP4
1995 - 405 Executive XU10J2
1996 - 406 GLX XU10J4R
1994 - 405 GTX XU10J2
x 1

Post by PowerLee »

Linchpin wrote:Apologies for posting in your thread, but Powerlee, is there something like this on the 306 Aircon system?

Mines dead too :(
Yes matey, The 306 & 405 use virtually the same set up for the aircon system.

Do your cooling fans work? Is the temp gauge working? Is the STOP or high temp warning lights on?

Have you tried bypassing the aircon pressure safety switch? DO NOT start or run the engine with it bypassed! ! !

Its a well known fault on the 306 that the aircon pipes along the front panel suffer from rust where the metal clips attach them to the bodyshell, Once the pipes rust & the gas is lost the pressure safety switch will stop the aircon system running.
Linchpin
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Post by Linchpin »

Talk about coincidence! I was driving along today and suddenly..

STOP! (whuuuuuuuuuurrrrr!)

Turned out to be the brown lead on the thermostat housing :)

My 306's aircon has never worked.

I havent tried the switch, the only thing i have checked is the clutch on the aircon compressor, that works fine but only if i supply voltage manually to it.
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