Coolant temp sensor?

Brett Dikeman brett at
Wed Jan 16 21:30:06 PST 2008

On Jan 16, 2008, at 3:41 PM, Phil Rose wrote:

> The coolant warning display flashing on (when
> level and temp are both OK) is a symptom of a
> defective MFTS.

Only if he has the solid-state MFTS.  Which may be the only thing in  
our cars these days, perhaps? Do they still make the mechanical version?

> Low boost-pressure and  inoperative A/C compressor are also symptoms  
> of a
> bad MFTS

There are separate switches for the Autocheck and the ECU/climate  
control overheat signals.  The ECU/CC signal is triggered at a lower  
temperature than the autocheck signal, at least in the mechanical  
version.  Autocheck's alert can be triggered by the MFTS *or* the  
coolant tank switch.

> , but the dead temp-gauge is a "dead giveaway".

Not necessarily true, since all three functions are separate devices  
inside common body.  The temp gauge is driven off a thermistor, and  
the two different overheat signals come from different switches pushed  
out by a wax expansion device (in the old mechanical ones.)


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