In a nut shell: Fans are not working.

If I test at the ALDL diagnostic terminal fans do not run. If I ground the Green/White wire at the ECM, primary fan starts and runs fine. So what do I do with that information, it appears that the ECM is not telling the fan to turn on. I have double checked that the ARAP "If Cool T < 14c, (58.5f) then divert" is enabled.

Outside of that, I have checked fuse and fuse links, all looks good. Any advice is very much appreciated.

 

mine was doing that, when i did an engine swap i installed a new fan temp switch on the manifold. Fan works fine now. The switch is on the front of the intake in the coolant passage. has a connector like the air intake temp sensor in the upper intake manifold

 

I will double check that, but my hand scanner is showing the temperature accurately and I would think that would mean the temp sensor was working. Thanks for the reply.

 

Can anyone verify it the above is true, If my scanner is showing the coolant temperature then the ECM should know when you kick on the fans? I am still not making any headway on this and it seems that the ECM is not grounding the wire. Anything else I can check?

 

Sorry - should proof a little better before sending.
Can anyone verify if the above is true, if my scanner is showing the coolant temperature then the ECM should know when to kick on the fans? I am still not making any headway on this and it seems that the ECM is not grounding the wire. Anything else I can check?

 

Ok, didn't get to much help on that one, but stubbled apon the fix. I am posting the fix just in case someone else ever runs into the same thing. I had a backup ECM that I tried just for the heck of it and all was good. Seems odd that the original ECM worked perfect except for that.

 

I had the same problem and bought a ECM on Ebay and it worked great. The one thing I noticed is when you do an ALDL test with the key on...the fan(s) should come on. With my original ECM they did not.

 

True that! That was the symptom that led me to the ECM as well.