Coolant fan runs constant when engines running and temperature gauge does not work

Hello,

This sounds to me like you could possibly have a short to ground on the ground wire from pin #47 of the Engine Control Module (ECM) to the Control Side of the Cooling Fan Relay Connector pin #C1. I have included a description of the engine cooling fan circuit as well as your vehicle's cooling fan circuit in the diagrams down below. I have hi lighted the wire to check for you, it is the dark green wire. Look for bare wire that is grounding out or damaged insulation. Please get back to us with what you are able to find out, please.

Thanks,
Alex
2CarPros

Thanks Alex. I did as you said and followed the electrical to and from the fuse boxes and to the temp sensor. And I did find an area of wires that had been chewed up by a mouse or something. There were three wires. A green, grey, and yellow wire. Which I repaired them, but it didn’t fix the issue. I’m going to have another diagnostics done today. Also was wondering if disconnecting the battery and reconnecting would need to be done. Thanks for you time.

Hello again,

Double check the dark green wire again. This is the wire going to the ECM. When the ECM wants the turn the fan on, it's through this wire that provides a ground path to the electromagnetic coil to energize it and send battery voltage to the fan. Get back to us with what you find out please. And no, I don't think you will need to reset the Keep Alive Memory (KAM) in the Power-train Control Module (PCM) by unhooking the battery.

Thanks,
Alex
2CarPros

Thanks. I did disconnect the battery and reconnect about five minutes later and all my issues are fixed. Check engine light turned off, gauge is working and fans working properly. Your help has been greatly appreciated.

Hello again,

Great. Excellent job. Please ask any other vehicle questions that you may have. We're here 24/7 for answers.

Thanks,
Alex
2CarPros

Hi Alex. I’m actually still having the issue. When I disconnect battery and reconnect the issue goes away for a short time and returns. And every time I disconnect and reconnect it fixes it. The only place there could be an issue with the dark green wire that I have not checked would be under the fuse panel it self. And I don’t feel comfortable pulling that apart. I’m afraid if I open it up I’m going to cause more electrical problems.

Hello again,

If you are careful and take your time with cutting the loom away, you should be alright. Remember if you do check the wire out, disconnect the negative battery terminal before starting anything electrical on your vehicle. This will prevent any accidental short circuits as well as prevent any damage from static electricity. Wire looms can always be replaced and they just hold the wires together in a nice tidy protective loom. Please get back to us with whatever decision you decide to do. We are here to help.

Thanks,
Alex
2CarPros

Hello again,

This could also be a problem with your vehicle's Engine Control Module (ECM). It provides the ground to both the high and low speed fan relays control side of the relay which energizes the coil and pulls the switch closed allowing battery voltage to reach the cooling fan motor. I have included in the diagrams below the Engine Cooling Schematic from Saturn with what I am talking about highlighted for you. Again, please let us know what you find out or decide to do.

Thanks,
Alex
2CarPros