Greetings!

The temperature guage on my '93 SE has started acting up :? ...It appears to be fine when cold/warming up but at some point after the engine has warmed up [ no, I haven't timed it, so I can't tell you exactly when] & the needle has stopped moving up and has stabilized for a while, it will fall down to the 'off' position...It will stay there for a while, & then go back to where it was....There doesn't seem to be any specific pattern to this, except that it always seems to warm up normally...
Now, I know that on my L27 engine, the Temp sensor is under the throttle body opening, on the firewall side....is there any troubleshooting I can do before I have to tear into the dash?...BTW: none of the other guages are acting up & the T-Stat was replaced with a 180 degree one this spring, and I have no cooling/overheating issues and no coolant leaks..

Thanx,
Andy

There are three tests that you can run. (from the 93 manual)

Disconnect the connector at the temp sender and turn the ignition ON. The gauge should go through it'* start-up dance and remain at minimum.

With the connector still disconnected, insert a jumper (paper clip) between the two leads and turn ignition ON. Gauge should remain at maximum after start-up.

Aquire 3 resistors: 1400, 93 and 40 ohms. Individually jumper the connector leads and turn ignitin ON. Gauge should read minimum with 1400 ohms, midscale with 93 ohms and maximum with 40 ohms.

You should probably do these tests twice. Once cold and once at normal operating temp. There'* really only three things that could be the problem: Sender, circuit (wires) or the cluster. The results of the above tests will help pinpoint.
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I had a similar problem with my temp gauge. It seemed accurate until normal operating temp was reached but it would "float" around eventually reaching maximum and would usually stay there. My problem was the cluster or more specifically the board that drives the gauge.

Thanx for the info!...

One question though: So the first test would pinpoint the sender as the problem, the second test the circuit as the culprit, and the third test the cluster?

Not specifically. There'* not one test for each component but more the results of all three will help determine what'* at fault.

Startup Dance? I thought only the Oil Pressure Gauge did that? Wait.. wait... should mine do that? Does the Temp Sensor need to be hooked up? You are scaring me, Randy!

Also, your problems sounds like a power wire is loose, since it instantly [well, as instant as that gauge can do it] drops down to the 'off position, not the 100* mark. Because off and on + being cold are two different positions. So if it lost connection to the sender [or the sender stopped sending a signal], it would go back to the 100* mark [or slightly below it]. But if the gauge lost power, it would drop back below the 100* mark.

Next time you get in your car, pay attention to where the gauge is with the ignition off, then turn the ignition on, and notice the change.

Also, my gauge'* lowest number is 100*, so substitue your lowest temp displayed wherever 100* is listed, if your'* varies.


-justin

You don't have the start-up dance (as I call it) in your car. The temp, oil and volt or boost gauges sweep through full travel and back to minumim before indicating the proper values. I suppose this is some kind of self test.

Where the [above mentioned] gauges rest at after shutting the car down has nothing to do with the accuaracy or proper operation of the gauges themselves. Typically mine will fall to minimum but after a minute or so will slowly rise to the 9:00 position. Still doesn't mean anything though.

Open...The dance is cool.

My cluster was bad. Actually I determined that my circuit board for the three gauges temp/oil/boost was bad. At cold starts they would work great. Once warmed up the three were all over the place.

One item to note from all of this. If you are having gauge problems you will not get a check gauges or check engine light. If you get either of these lights and the associated dinging...PAY ATTENTION to them. Something went wrong and your car is telling you to pull over quick and turn off the car until you figure out what just happened.

What I am saying is you can ignore the gauges...but don't ignore the DIC warnings to check gauges. DIC is real from the PCM...the readings on your gauges may not be.