Constant Engine Fan

Hey Everyone,

I have a 1989 Buick Lesabre 3.8L with dual engine cooling fans. A few weeks ago the Main engine fan stopped working due to a malfunctioning ECM unit. I checked all the fuses and relays before replacing the ECM. That solved the problem sort of. Now the fan comes on anytime the car is running. Even after the car has sat up over night when i know for a fact that it's cold, the fan turns right on as soon as I start the car. I repalced the temp sensor other day still the fan turn right on. This is going to be a problem in the winter since the car will never get to the proper operating temp. The car is givng a code 15. "Engine coolant temp sensor error (low temp indicated)" I have the radiator full of 50/50 coolent. Other then that the car runs great. Any help would be greatly appricated.

There should be two temp sensors, one for the engine temp guage, and one to enable the electric coolant fan to turn on at a certain temp 220f.
The coolant temp sensor for fans should be located on the radiator.

This 3800 uses 2 Temp senders, one for the Dash and the other for the ECM... The ECM controls the fans directly via the relays.. One for high speed and the other for low speed... You will have 2 relays for the fans, if memory serves they will be near the air box... I believe that one of the relays is sticking...

I replaced the relays but the fan still runs. That was good thinking thou. Do you have any other ideals? I really don't want to go to the dealer.

Do you mean the ceramic looking switch? If so i replaced that also a while ago I just forgot to mention it in my post. Are one of those wire always suppose to be hot?

How about this... Has anyone scanned this car to see how hot the ECM thinks the engine is?

Thats a good ideal. Il try and get it scanned hopefully I can avoid the dealership.