I have a nagging problem. On my 1992 LT1 my dash coolant temp gauge is always reading "LO" and runs very rough in fact it won't idle. I replaced the coolant temperature sensor on the water pump twice and I get 5 volts on the connector. If I disconnect it I get the Code 15 and then the temp reads 142 and it runs a little better but still rough. Any suggestions would be greatly appreciated since I am a new memeber.

What year and which sensor?

1992 LT1 and it is the coolant temperature sensor on the water pump.

It sounds like the wires have a bare spot and are shorting out.

It must be because I looked at the schematic and there isn't much else there that it could be. Thanks

Quote:

Yea, you're going to have to check the wires all the way to the ECM.

It's doughtful that you got 2 new sensors that were bad.

Pull the connector and put a jumper on the yellow wire and ground the jumper - does tha analog gauge go to full hot?

Does the 15 only set when you pull the connector? Or was it set before you pulled the connector? And have you cleared that code and tried it again.

There is another coolant sensor for the guages. It is located on the right head between 6&8. Are there any other codes? You might have to reset the tps. It looks like the front coolant sensor also ties into the tps.

The sender on the right head only feeds to the analog gauge.
The one on the water pump feeds the readings to the ECM, which in turn also feeds the digital gauge. If the sensor shorts out the ECM thinks it is in tha artic and feeds way too much gas to the engine, which is why his won't idle.

And... if the temp sensor on the waterpump fails, it will freak out the engine controller, the range between the coolant and oil temps freak out, and the engine will stall out. Ask me how I know.

I would check the harness. It is possible it has been laying against the serpentine belt or something to that effect. The harness goes down the right side of the engine, up near the injectors. IIRC, it goes into the same main split loom.

Check the back of the engine, there is a chance that the split loom has failed.

142 is some strange default it goes to... and I don't quite know why. Very odd.

As mentioned, the sensor on the right head is a dummy and only presents a temp to the analog gauge. It has no bearing on the operation of the engine.

Isn't the coolant temp sensor (cts) and the analog gauge sensor/sending unit two seperate part numbers? If so, maybe you were given the wrong sensor?

two part numbers, two different connectors. The one on the waterpump is a 2 wire, the one on the head is 1 wire.

I assume this is the digital gauge.

Is this only happening in the morning? How cold is it outside?

The word "LO" will show on the orange LED display if the oil and coolant temperatures are below 32*F