OK, took my car out last night and the temp gauge got up into the red while sitting in traffic. The fans would not come on and my AC compressor is locked up so I couldn't use that to try and get them to turn on. I know the guage is right because I just replaced that sensor a few weeks ago. Today I hooked up my laptop and saw that the sensor in the waterpump is also working correctly because the ECM was receiving accurate temperatures. When the temp got to around 233 or so, the fan on the drivers side turned on and shut off once it got back to 230. The passenger side never came on. I switched around some relays and nothing changed. Shouldn't the drivers side fan be coming on at 225 and the passenger side at 230 or similar? What could my problem be? I have been wanting to install a manual fan switch for some time, I guess I should just do that now and be done with it.

 

Have you scanned it for codes? DTC 28 sets for Quad Driver #3, which is the source of switching for the fan and AC relays.

 

I will scan it this afternoon. Would having the AC relay pulled cause the fans to not work properly? I removed it when the compressor locked up so I wouldn't mistakenly turn it on.

 

Alright, finally had time to scan for codes and there were none. I jumped the terminals on the OBD port and both fans came on so there is nothing wrong with them. What should I try next, I am stumped?

 

mine did the same thing once in a while. So i also wired the fans up to a switch just in case it happens again.

 

Sounds like your trouble might be intermittent.