Good morning all,
I've got an 86 944 Na with 132k miles that I got a few months ago as a project. When I got it the temperature gauge was dead, but all the fans worked as they should cutting on low and high. I replaced the 2 wire sender for the gauge and light now it works normally I think. I drive it a short 10-mile commute sometimes to work and the temps are normally in the middle range. Yesterday, on my way home I had to sit a bit longer than usual in traffic and warmer temperatures for the day (70s) the temp bar rose to the 3rd mark maybe a tad above and the top of the gauge illuminated red and the central warning light came on. The fans cut on and the temp went back down the mid-range but the light on the gauge and the central warning light stayed lit. Is that normal?
Thanks in advance.

 

The gauge... the warning light... the fans... all separate sensors.. sounds like your first stage of fan is not working. Either a bad sensor in the radiator or you have an open somewhere in the resistor circuit that is below the windshield.

 

So, where would the sensor for the light be? Controlled by DME temp sensor?
The temp sensor I replaced had two terminals, one small and one large. I thought one was for the warning light... Ill replace and test the thermo-fan switch, the relay looks good in the box, doesn't get hot and the solder looks great.

 

The gauge and idiot light sensor is right next to the one you replaced. You put in the two pin blue colored sensor. The one for the light is only a single wire about one inch away from the two pin one

 

The sensor I replaced was not the blue one with the bosche style connector, it was the one with the 2 spade terminals, one small and one larger. like the one in the picture on the right.

 

Yup one is dime. Other is gauge idiot light.. not next to a manual now.
pull the plug on your rad and jump two pins at a time to make sure your fans run low and high.. if all of that is good then you may have some air in your system.

 

Thanks, Ill check this evening and report back.

 

Alright, unplugged the thermofan switch. Jumpered the pins and low and high work. Pulled relay checked resistance on v1 v2 and M1 M2 that go to the resistors nothing was open.
RE-Bled the bleeder screw, started up and watched. Temperature rises to 3rd bar light and ! Light come on, fan cut on low shortly after, temperature drops back to middle, ! Light and overheat light staying illuminated.
Sensor is 2 months old.
What would you check next?


After fans

When fans come on

 

So I replaced the temperature sender that I replaced under warranty. Now I got no light at the 3rd bar and the fans cut on like normal. I think the temperature sensor was faulty or was low on the temperature value for the light which would trigger the !. Thanks for your help!