tgroghan

Okay,

I am still have a problem of the 1991 reaching high temps before the
electric fans come on. I read thru the manual about when they are
suppose to come on and from the gage inside the car it doesn't seem like
they are coming on at the right time. I used a GM Code Reader to
diagnois the problems, a code 12 came up which means either no codes or
the ECM is not hooked up. I'm guessing the no codes.

The strange thing was when I hooked the Code Reader and turned the key
switch to ignition to "ON", the fans came on while diagnoising the car.
Does this happen on all the cars with computers or does that send up a
red flag that there is a problem w/ grounding?

Thad

SunCr

Yep, fans come on when you ground the diagnostic connector. Code 12 means that ECM believes that all is normal. There is no Code for the fan(s) so have the dash temp readout verified with a scan tool and that the main fan comes on at the temp indicated in your manual. If not, then the ECM isn't responding to the sensor input at the appropriate moment, though I wouldn't fret about one or two degrees. Also, the scan readout may be a few degrees different from your gauge because it relies on a different sensor. If there is a large difference between the scan and the dash read out, then the gauge sender may be faulty. However, you could also have a dirty or partially blocked cooling system so have the system thoroughly flushed if you haven't all ready done that.

vettenuts

Please define how you are determining "high temps" before the fans come on? Are you using a scanner or the analog gage on the dash? Also, is this a completely stock setup? Sorry for the questions.

tgroghan

Stock setup, okay just got it scanned, 225 kicks fan #1 on, so it works like it's suppose to. I did learn that the fan on the dash is a tab it off, so it's about useless. After reading the other problems of ppl finding out these things run warm, when sitting still.

Now winter is setting it, I won't have to really worry about it. I won't have this car much more than one more year anyways. Though I do want to keep it running well for the meanwhile, as if I was gonna keep it forever.

Thanks


[Modified by tgroghan, 2:58 AM 10/5/2001]