94 Ciera Temperature Guage not working

[rp3710]

I recently purchased a 94 Olds Ciera with only 48,000 miles. It has the 3.1 liter. The temperature guage does not work. I suspect that it is the sensor and not the guage. However, has anyone heard of the guage failing on these vehicles? I am not sure which is the guage sensor. I have four choices:
1. A one-wire sensor in the block by the oil filter which I suspect is the oil pressure switch (there is no oil guage).

2. A two-wire sensor on the intake by the thermostat housing which I suspect is the coolant sensor for the fuel injection system.

3. A two-wire sensor that is threaded into the right corner of the rear head.

4. A three-wire sensor that is installed in the block by the starter.

Any help with problem would be greatly appreciated. Thanks.

[Carlspike]

My book says that the MFI engine has the coolant temp sensor on the intake manafold water jacket or near (or on) the thermostat housing. If you are going to replace it then get the new sensor and match it with the one on the engine.

[3400runner]

The coolant temperature sensor signals the electronic control module when the coolant temperature rises and causes the ECM to activate the radiator fan. You might try warming up the engine and letting it idle to observe if the radiator fan comes on. If the fan works ok than the sensor is probably ok.
According to Haynes manual the resistance of the coolant sensor will change by approximately 500 ohms when the engine goes from cold to hot if the sensor is good. I didn't bother trying to measure the change in resistance because access to the sensor's electrical connections is tight.

I replaced the sensor in my daughter's 95 ciera last weekend. If you trace the upper radiator hose back to the engine you will see the coolant temp sensor behind and to the left of the hose. The leads are black and yellow. The toughest part of the job is releasing the electrical connector, due to tight space.
Wrap the threads of the new sensor with teflon tape and torque to 17 ftlb.
The electrical connector goes on a lot easier than it comes off.

[rp3710]

So the temperature gauge receives it signal from the ECM? I have been told that this configuration wasn't present until 95 and that up until 94, the dash temperature guage used a seperate sensor.

[Carlspike]

My 94 2.0 has a single sensor for the ECM and gauge, so it's possible you only have one also. They might have switched them all over to single sensors in 95, but some cars may have gotten that earlier.