Expert: Harold - 4/11/2004

Question
I have a 1997 Chevy Camaaro Z28 SS. I have began to have problems with several items. The first issue started with the radiator fans. They do not come on and the engine begins to overheat. I tested the fans, they work fine. I replaced both temperature sensors. I tested the wiring back to the PCM, no problems. I can manually engage the fans by grounding the wire to the relay . The low power fan does engaged when the AC is on. Along with that problem my eng. service light is now coming on. I put it on an analyzer and it shows the egr is the problem. I am also experiancing low voltage reading on the instumment panel. Thinking these issues were related to low voltage I tested the alt and it was going bad so I replaced. After replacing the alt. all of the symtoms are the same. I suspect a grounging issue somewhere but have no idea where to begin.

Can you advise?  

Answer
The PCM should ground the fan relay to turn on the fan between 105 110 deg.C. Check the wire at the relay to see if you get a ground at that temp.
Also an EGR valve that is sticking open can cause it to run a little hotter than normal.
About the low voltage condition...the gauge in the dash may not be that accurate. Check the "real" voltage with a goo digital meter.