carychip@hotmail.com wrote:
> Thank you for the good explanation Rascal and Jon. A person could
> get educated here. I had no idea axles had vents. I still think
> that gizmo spliced into the heater hose must be a temp sensor that
> goes to the instrument panel because it has a thin electical wire
> that goes to the firewall. The wire seems too thin and wiry to be a
> vacuum hose. The temp sensor near the water pump has 2 wires I
> think and is connected to the computer. Where does the temp gauge
> normally get its reading from? I figured the truck had 2 water temp
> sensors, 1 for the computer and 1 for the guage. But heck, you
> fellers know better than me. I'm just a guessin.
You are correct on the temperature sensors. As of 1997, only one
temperature sensor is used for both the gauge and the computer, but up
through 1996, there is a two wire sensor used for the computer and a
one wire sensor used for the gauge. You already found the 2 wire
sensor for the computer, which should be located on the front, driver
side of the intake manifold. If you look at the front, passenger side
of the intake manifold, you'll find the one wire sensor for the gauge.
(It is likely to be a purple wire with a yellow stripe.) On the
pre-Magnum engines (which is what you have), the wire for this gauge
sensor wire just snaps down on top of a threaded post on the temp sensor
screwed into the intake manifold. (Unlike the 2-wire computer sensor
which plugs into the sensor.)
Regarding the gizmo, I guess you'll just have to trust us on this;
its the water control valve. :-) Its got sort of a little cannister
on it, and the "wire" comes out of that, right? It is indeed a very
small line, about the same size as a 10-12 gauge electrical wire
perhaps, but it is indeed a vacuum line. The cannister contains a
diaphragm which shuts a valve in the water line when vacuum is
applied. If you visit the following link, you'll see a diagram that I
scanned for you from the factory service manual which shows the water
control valve. Its from a 1990 manual, but it should be the same:
Even beyond that, I'll give you another reason why it can't be a
temperature sensor. :-) You have said that its only got one wire
running from it towards the dash. If it were a temperature sensor it
would need two wires - one for the signal and another for the ground.
Although there are many temperature sensors which have only one wire,
this is because they obtain their ground via the metal from the intake
manifold or water pump which they are screwed into. In this case,
since the gizmo is installed in the heater hose, it is electrically
isolated from the rest of the vehicle, and would need a ground wire
connected to it in order to function as a temp sensor.
If you need further proof, go take a look your engine and find the
sensor which I have stated above is for the water temperature gauge,
and notice how it disconnects. Start the engine and run it up to
temp, or so that the gauge is giving you some readings at least, then
disconnect the wire and notice that the gauge no longer works. Be
careful of the fan and belts if you disconnect it while the engine is
running, it might be better to shut off the engine, disconnect the
wire, then restart the engine (or just turn the ignition key to the on
position so the gauges work.) By doing that, you can prove to
yourself that it is the sensor in the intake manifold which is
connected to the gauge, and thus the "gizmo" can't be the water temp
sensor.
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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