Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
What does the temperature gauge read with the engine off/cold, key on/engine cold and finally key on, engine warm?
Also, I need the 8th digit of your vin number so I know which engine this is.
Are you saying that it goes to the full scale when the key is turned to start?
Can you gain access to the rear of the instrument cluster and check the voltage right at the gauge?
Wait just a minute on that. I see that both wires from that temperature sensor go to the ecm.
So, it must be the ecm that controls the function of the gauge.
For now, here are the 2 wiring diagrams showing the wiring to the ecm at pins x3 35 and 55.
The sensor is at the bottom of page 3.
The only wires to the sensor go to he ecm, so yes.
Which wire by the way has the voltage, the yellow or pink?
Yes, the ecm is under the hood on the drivers side.
Check the voltage again by backprobing the very same wire at the ecm.
I'll try the diagram again.
The ecm can most likely be flashed or reprogrammed but I would retrieve the codes first if the voltage is still the same at the ecm.
This is the explanation from the Mitchel manual and it assures somewhat what I already thought:
The instrument panel cluster (IPC) displays the engine coolant temperature as determined by the engine control module (ECM). The IPC receives a serial data message from the ECM indicating the engine coolant temperature. The engine coolant temperature gage defaults to 60°C (140°F) or below if:
So, basically the ecm/computer should have a code stored. Let me know when you get the code.
Are you sure then that you are looking at the ecm?
This should be what it looks like,
Chilton says it's on the lower air cleaner housing.
I believe you have to remove the air cleaner outlet duct. Here are the instructions on replacing it so it should show you how to gain access to it.
And to reprogram it you will need a tech 2 scan tool or equivalent and follow the instructions on the GM techline.
No, clearing the code will do nothing as far as fixing it goes. As a matter of fact, you should not clear the codes until it is fixed.
I don't know which wire goes to the gauge or instrument cluster and anyhow I believe I did see that it was a computer data line and I don't think they can actually be tested for voltage per se. They should be checked with a scan tool. I would drive the vehicle to an auto-parts store and have the computer codes retrieved and ask about reprogramming the ecm while you are there.