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156 2.5 temp gauge problem

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5K views 10 replies 3 participants last post by  jwq 
#1 ·
Hello my name is Chris.

Why I bought a Alfa ?
Because my dad before got 2 164 3.0 12v and after this a 166 3.0 24v.
My dream was a V6 Alfa as first car and the dream came true.

A year ago I bought a 156 SW 2.5 CF3. The Temp gauge at this time was not working.
The Radiator was gone so I chanced it after I bought the car.

With The new Radiator in the car the Temp gauge suddenly were alive.

Between them, another battery was installed , before 72Ah now 60Ah is this a big problem?

After 3 Months the Temp Gauge was going off at 90°C.

After this I thought stat is gone so I got a new one and a new sensor.
With the old sensor same problem.

My Dashlight is flickering then the light is on. And in reverse my radio stop playing music for 1 second.

With another instrument the problem peresists.

In the ECU the Temp is ok.

I think its a earth problem from where the gauge is getting earth?
From where is the sensor getting earth, and which pin is earth ?

I also got a video what my Gauge is actually doing.



The real temp in the video was 80-90°C .


I hope someone can help me with my problem.
Many thanks in advance.

Sorry for my bad English Im from the Netherlands.
 
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#2 ·
the 156 uses 2 different temperature senders, one for the ECU (motormanagement), one for the temperature guage. In your case the ecu one seems to work, the guage one not.
On most 156 models, the fysical temp. sender actualy contains 2 elements with seperate electrical connections in the electrical plug.
Early models had 2 completely seperate sensors.

Are you sure you replaced the temp sensor with the correct version (i.e. in your case probably containing 2 sensors) ?
 
#4 · (Edited)
I asked my local alfa dealer about 2 senders . The answer was my car only got 1 Sender in the stat the car is from 2002 it´s a CF3.
.....
I don't think so, however, as said, it could LOOK like one sender as the fysical unit actually contains 2 temp sensors, which you can see/check looking at the electrical plug on the sender.
It's been discussed extensively on this forum ;)

from elearn:
<snip>
CENTRAL MODULE
The module includes:

fuel gauge, with reserve warning light
engine coolant temperature gauge, with maximum temperature warning light
analogue clock

1, Fuel level gauge

2, Reserve warning light

3, Analogue clock

4, Engine coolant temperature gauge

5, Maximum temperature warning light

The fuel level is displayed by an electronic circuit inside the module, which operates the gauge and also the warning light for the reserve (about 7 litres).

The internal software 'dampens' the signal to prevent fluctuations.

When the ignition is turned on, the warning light comes on for about 4 seconds as a self-test, then goes out.

If it flashes and stays on, a fault has been detected in the connection or the level gauge.

The coolant temperature gauge is controlled directly by a sensor on the engine.

The maximum temperature warning light is controlled by a sensor on the engine with another signal, independent of the gauge.

During starting, when the ignition is turned on, the maximum temperature warning light comes on for about 4 seconds as a self-test, then goes out.

The analogue clock consists of a face with hour and minute hands. It is electronic with a quartz oscillator. It is adjusted by means of a button inside the dial.
 
#9 ·
The wire job is done and my problem is solved. Now the temp gauge is working fine I think, always between 70 and 90?
In traffic jams I think it goes to 90.
The wire color was grey. After the first plug in the black box at the plenum the wire was brown. After the next plug in the inner space the wire was grey/green.
I have the cable retracted without the connectors.

big thanks for the fast replay and great help to you jwq.
 
#10 ·
That is normal behaviour for the temp gauge. Goes up to the (about) 70 mark within 3 to 7 minutes from startup (dependent on exterior temperature) and then fluctuates between 70 and (just over) 90 depending on road speed and airflow, never dropping below the 70.
 
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