OK to do this?

Technical aspects of automobiles, et. al., post #21,326
Author:
Date:
Subject:
 j
 2008-07-09 14:09:33
 OK to do this?
The electric radiator fan quit working on my 94 Chevy Corsica 6 cylinder. In
order to test the fan I thought I should unplug the 2-wire plug from the
sensor that is screwed into the block and jumper the 2 wires together at the
plug to see if the fan comes on. Am I on the right path with this? (I
replaced the sensor last year so I doubt that it is a bad sensor)

It seems to me that the sensor is merely a thermal switch that "shorts" when
the engine coolant gets hot (to make the fan come on) and that by jumpering
the wires on the plug I am simulating the switching action of the sensor. I
don't want to actually do this without first knowing what you guys have to
say about it. Thanks for the help.
Author:
Date:
Subject:
 bobj
 2008-07-09 16:40:38
 Re: OK to do this?
j wrote:
> The electric radiator fan quit working on my 94 Chevy Corsica 6 cylinder. In
> order to test the fan I thought I should unplug the 2-wire plug from the
> sensor that is screwed into the block and jumper the 2 wires together at the
> plug to see if the fan comes on. Am I on the right path with this? (I
> replaced the sensor last year so I doubt that it is a bad sensor)
>
> It seems to me that the sensor is merely a thermal switch that "shorts" when
> the engine coolant gets hot (to make the fan come on) and that by jumpering
> the wires on the plug I am simulating the switching action of the sensor. I
> don't want to actually do this without first knowing what you guys have to
> say about it. Thanks for the help.
>
>
You ought to first go to the library and look up the circuit
in their Mitchell's manual section...
Author:
Date:
Subject:
 W. Stief
 2008-07-09 19:39:10
 Re: OK to do this?
j wrote:
> The electric radiator fan quit working on my 94 Chevy Corsica 6
> cylinder. In order to test the fan I thought I should unplug the
> 2-wire plug from the sensor that is screwed into the block and jumper
> the 2 wires together at the plug to see if the fan comes on. Am I on
> the right path with this? (I replaced the sensor last year so I doubt
> that it is a bad sensor)
>
> It seems to me that the sensor is merely a thermal switch that
> "shorts" when the engine coolant gets hot (to make the fan come on)
> and that by jumpering the wires on the plug I am simulating the
> switching action of the sensor. I don't want to actually do this
> without first knowing what you guys have to say about it. Thanks for
> the help.

Short form: Don't do it

Long form: the CTS is a varistor(?), shorting at the plug could damage
the body control module.
$$$

check the switch at various temps with an ohm meter.

Or just try a known good CTS.
Author:
Date:
Subject:
 aarcuda69062
 2008-07-10 07:40:37
 Re: OK to do this?
In article <kTcdk.13772$uE5.109@flpi144.ffdc.sbc.com>,
"W. Stief" <[email protected]> wrote:

> j wrote:
> > The electric radiator fan quit working on my 94 Chevy Corsica 6
> > cylinder. In order to test the fan I thought I should unplug the
> > 2-wire plug from the sensor that is screwed into the block and jumper
> > the 2 wires together at the plug to see if the fan comes on. Am I on
> > the right path with this? (I replaced the sensor last year so I doubt
> > that it is a bad sensor)
> >
> > It seems to me that the sensor is merely a thermal switch that
> > "shorts" when the engine coolant gets hot (to make the fan come on)
> > and that by jumpering the wires on the plug I am simulating the
> > switching action of the sensor. I don't want to actually do this
> > without first knowing what you guys have to say about it. Thanks for
> > the help.
>
> Short form: Don't do it

Wrong answer.

> Long form: the CTS is a varistor(?),

Negative temperature coefficient thermistor.

> shorting at the plug could damage
> the body control module.
> $$$

Someone should tell that to GM because it's part of the diagnostic
routine and has been since 1980.

BTW, that car doesn't have a body control module.

> check the switch at various temps with an ohm meter.

Check the sensor at various temperatures with a volt meter (voltage
drop).

> Or just try a known good CTS.
Author:
Date:
Subject:
 Paul
 2008-07-11 12:37:20
 Re: OK to do this?
j wrote:
> The electric radiator fan quit working on my 94 Chevy Corsica 6 cylinder. In
> order to test the fan I thought I should unplug the 2-wire plug from the
> sensor that is screwed into the block and jumper the 2 wires together at the
> plug to see if the fan comes on. Am I on the right path with this? (I
> replaced the sensor last year so I doubt that it is a bad sensor)
>
> It seems to me that the sensor is merely a thermal switch that "shorts" when
> the engine coolant gets hot (to make the fan come on) and that by jumpering
> the wires on the plug I am simulating the switching action of the sensor. I
> don't want to actually do this without first knowing what you guys have to
> say about it. Thanks for the help.

Yes you can jump it, however I would start with the fan itself.
That car is old enough to have worn the fan brushes down to nothing.