Ok so my car overheated the other day and pumped a bunch of coolant out of the bottle, fortunately I was able to get it off the road asap and towed home. I let it cool overnight, added fluid and the water pump was making a weird noise, so I turned off and replaced the water pump(was under warranty) It sounds fine and I let it run till water temp got to 216 but still no fans now I know they kick on at 216 but the dash gauge is starting to approach the red and it is really really hot under the hot. Now when I turn the AC on the fans come on at low speed but when I did the test for jumpering the DLC with pin 5 and 6 (96 Z28 stock) and turn the ignition to ON the fans do not come on. My next step is to replace the thermostat with a 160 one and then running the car and pulling the leads of the waterpump temp sensor to see if I get a SES light and the fans on. Any other ideas of what might be happening? Could the PCM be going bad/flaky?

 

I've had the same problem since spring 08', no one could figure it out, and a couple of the guys have the problem too, (we removed the air pump too because that kept blowing fuses) the only way my car still goes without overheating is that we bypassed (bridged a wire where the relay goes) the relay in the fuse box under the hood and now the fans run all the time. This spring we are going to try a manual switch to turn on and off the fans. sorry it doesn't help, maybe someone out there knows!!!????

 

Ok I unplugged the sensor wire to the temperature sensor and after about 30 seconds the fans kicked on high. Now I did not get an check engine light but I am not sure if I am supped to (?)

 

No, the fans don't come on until 226° as stock.

If you pulled the connection at the water pump, you should have gotten a trouble code. Your fans do seem capable of running, since they did come on when you did that.

 

if I did not get a trouble code what does that mean? my computer is bad? I put my hypertech programming back on and now everything is fine again, they come back on like they are supposed to at 196. All of this started when we had a huge rainstorm here in San Diego, now that I guess everything is dried it is all working again so I am starting to think maybe I am having wire harness problems.

 

Thanks Shoebox for the great write up about the fans and the schematics for wiring in the manual override switch!! I just completed it yesterday and went as far as getting two of the 10 pin connectors so I can always go back to stock in a matter of seconds. I added the switch to the little panel where the lighter plug sits and with two red LEDs to indicate fan speed it looks and works great!