Coolant Sensor Replaced but Radiator Fans Wont Turn on


Problem with my 1996 Oldsmobile/ Aurora.
Engine size 4.0 V8.
Repairs= replaced coolant temp sensor on drivers side of the car fans still don't come on.

Question = I bought the car for a thousand because it wasn't running and I replaced some parts on the car to get it started and stay running and now my engine cooling fans don't come on when they are suppose to, Now I've been on my computer for a couple of hours trying to find a solution to get them to come on.

I've took the coolant temp sensor wires out and the fans came on as they should but put it back on and the fans went out.

Is there any other sensors I should be looking at? other than the coolant temp sensor, because I was told there might be more than one temp sensor on this car, there are to much sensors on this car its crazy, you know I've almost spent a grand on sensors alone to get this thing started and stay running now its just those darn rad fans I want to come on when there are suppose to Please help me! Its a very good looking car and I am a back yard mechanic that's been fixing neighborhood cars for awhile and can't believe this one stumped me Cheers mate!!

Answer: Unplugging the sensor causes the PCM to default the coolant temperature as -40 degrees F. This is why the fans go on. Normally this means that the wiring and the PCM (which turns on the fans) is functioning. I would suspect a faulty sensor, but it was replaced. There could be a problem in the wiring to the PCM. High resistance or a partially broken wire causing the temp sensor signal to the PCM to be skewed / inaccurate. You need to have a scanner on it to look at what the PCM is showing as the coolant temp. The fans wont come on low speed until approx. 225 F.


Olds Aurora Blower Shutting Off

2002 Olds Aurora Engine Size : 3.5
Question: heater blower keeps shutting off and on when i hit bums in road.

Answer: There's a few things that can cause that problem. You could have a blower motor that is shorting out internally when jarred by the bumps in the road. There is also a blower motor resistor/control module that can go bad and cause the same problem. Those are more likely than the blower motor itself, but both should be checked. Other than that, a wiring problem or harness that is touching someplace it shouldn't could do this as well. You really need to remove the lower trim panels of the passenger side dash and get up under there to check things outs. Try tapping the blower motor and control module with your hand to see if you can get it to act up and find the cause of your problem. A test light would come in handy to see if and when you're losing power or ground to the unit.


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  • Guest - guest2

    iv'e changed the temp,sensor,,the thermostat,replaced the fan,and still no rad/fan?what am I missing?

  • Guest - guest

    Changed coolant temp sensor for fans not coming on. Still problem with fans running all the time and temp gauge always reads C. Both fans are on and I think this causes the engine to run too cold.

  • Guest - Tom Burns

    Manual says right fan should come on automatically when a/c is turned on but still won't come on, a/c doesn't want to stay on either!!

  • Guest - Stan

    In reply to: Guest - Tom Burns

    The engine light will stay on unless you clear the codes. The fans not running can be a relay problem, bad fan or bad PCM.

  • Guest - guest

    In reply to: Guest - Stan

    Is your cam sensor bad with a PO341 error? Mine reads bad and light stays on check. Also had over heat corrected by change of the temp sensor, light is still on and the error codes still show. Auto zone no longer will clear out the codes. So now I have to change my cam sensor and have someone clear out the codes.

  • Guest - Tom Burns

    2005 Silverado 5.3L - check engine light came on noticed temp gauge wasn't working. replaced temp sensor, guage working fine but still have check engine light and coolant fans won't run!

  • Guest - Guest

    Temp sensor may not control the fans. See if you car is equipped with radiator fan switches, those would turn on the fans. There are also relays that control those fans.

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