first gen 4.3 temp gauge problem
 

hello,everybody,
i have a 4.3 s10 blazer (1991) with digital cluster.

i noticed that the temp gauge stays almost all the time 100°f.
sometimes it comes up a little.

the heater is working fine .

now i think it's maybe the thermostat but i think that the heater wouldn't blow hot air if you drive 10 miles.
maybe the coolant temp sensor , but is there just one or are there 2 sensors (switch)?
can somebody tell me where it's located and how i can test it without a removal of the sensor from the engine.

or maybe is there also another thing that can be wrong?

the car doesn't smoke , drives very good, the fuel cosumption is on a high level.
heating blows hot air , airco works fine.
there's no water mixed with the oil and also no oil in the coolantwater.and the radiatorfan clutch is also okay.

thx in advance

vincent

I use the exploded parts diagrams at places that sell OEM GM parts to get a handle on where items are located. GM Parts Express is one that comes to mine. You might look there for diagrams.

I'd try to measure the temperature of the hoses or parts of the radiator to get an independent measure of the temperature of the water. If my independent measurements are what I would expect, then I would suspect the temperature sending unit.

My 91 had 2 temperature sending units. One for the gauge and another for the engine's computer. They can be tested by measuring the resistance and the temperature and comparing your readings to a specification chart that lists what the resistance should be at any given temperature.

where are they located?

Preliminary checks.
Switching ignition to RUN powers the instrument cluster. The digital cluster (LCD) should illuminate all gauges dashes. Check that all are intact.
The analog one (i don't know) but normally they do a quick full scale deflection and return to 0.

The 94 4.3 V6 should have:

ECT sensor (engine coolant temperature) which is a thermistor (resistor). Resistance decreases with increasing temp and is measured with a 5v signal from the ECU. 1365 Ohms at -40F and 55 Ohms at 266F as a basic reference.

It is located in the right hand cylinder head

Manual says for troubleshooting: disconnect at the temp sender.
Now gauge should read low.
Then ground the green wire with a fused cable.
Gauge should indicate hot.
If the wire is good, the sensor is shot.

The manual actually does not tell about the second temp sensor. I had to replace that one some 19 years ago that's why my memory let's me down a bit on that one.
One of the sensors is for the temp gauge, the other one is for the "OVHT" warning.

do you know where the second one is located? is this the one near the thermostat?

already thx

I'll have a look at mine.

What is meant by "fused cable"?
Following, same problem, analog cluster, gauge never gets off of 100, in addition to a high idle.
Thanks for the heads up on the thread.

Ah - the manual is on the very conservative side. They try not to fry things.

In order to jumper something it is smart to have a little fuse box in the wire. If you inadvertently connect something to ground which has power on it (as in battery power) it blows the fuse instead of your sensor.

I would opt for the smallest fuse like 1 Amp or even 0.5 Amp and buy a bag full.

Sensors seldom have more than that. Multimeter is always the favorite.

if i turn the ignition key on power on , the temp gauge goes all the way up and then back to zero .
like you said error_401. ( do you know already where the second sender is located?)

but the temp gauge is not the only small problem i have .

but i don't rush it :-)


another question , the side panels in the trunk , are they also mounted like the door panels? with the white plastic things ?
i'm gonna put aftermarket speaker in it and will place an amplifier , also an aftermarket car stereo