CoupeDTS Posted November 15, 2010 Report Share Posted November 15, 2010 Working on a friends 99 Deville base. The radiator was leaking and his fans were not turning on. We replaced the radiator today and are now trying to figure out the fans. The dashboard digital readout will go above 230 degrees and the fans wont turn on. Even if you click on the a/c no fans. Ive read about checking fuses for the a/c and other things but all fuses are good. There are 3 fan relays under the fans, I had those tested and they all tested out good. So the only other thing Ive read is maybe the temperature sensor by the thermostat. But if that wasnt working would it be reading temperature on the dashboard? Or is that a separate sensor? Or different part of that sensor that could be ok? Anything else to check on? Im sure the fans themselves are fine, why would both go out at the same time? But i could hotwire them just to check. Thanks * 1966 Deville Convertible * 2007 Escalade ESV Black on Black * 1996 Fleetwood Brougham Black on Black V4P -Gone* 1983 Coupe Deville Street/Show Lowrider -Gone* 1970 Calais 4dr Hardtop GONE* 2000 Deville DTS - Silver with Black Leather and SE grille GONE* 1999 Seville STS - Pearl Red GONE Link to comment Share on other sites More sharing options...
Dr.Fiero Posted November 15, 2010 Report Share Posted November 15, 2010 Fans are controlled by PCM by ground pins 32 & 33 at the PCM. Fuses "cool fan 1" and "cool fan 2" feed the fans (how cryptic huh?)and supply power to the relay coils. Make sure nobody left off the single ground wire that grounds... well... ALL of it! Might explain why it all died at the same time. Link to comment Share on other sites More sharing options...
Dr.Fiero Posted November 15, 2010 Report Share Posted November 15, 2010 Oh, added note... looked it up, and the common ground point seems to be on the r/h frame rail at the top, maybe a foot back. Couple wires piled on top of each other. Link to comment Share on other sites More sharing options...
rockfangd Posted November 15, 2010 Report Share Posted November 15, 2010 there are 2 coollant temp sensors, 1 is for the pcm and one is for tthe IPC readout. The one for thhe IPC readout haas a single wire and I believe the other has 2 pins. The A/C should kick on the fan on the passenger side, I believe the primary(driver side) fan kicks on around 215 and the secondary fan kicks on about 230. GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
CoupeDTS Posted November 15, 2010 Author Report Share Posted November 15, 2010 Fans are controlled by PCM by ground pins 32 & 33 at the PCM. Fuses "cool fan 1" and "cool fan 2" feed the fans (how cryptic huh?)and supply power to the relay coils. Make sure nobody left off the single ground wire that grounds... well... ALL of it! Might explain why it all died at the same time. I think we only found 1 50amp maxi fuse for fans and it was ok. Im thinking just unplugging the 2 wire temp sensor should default the fans to be on, its like that on my fleetwood. So were gonna try that. Its only a 10$ sensor so might end up changing it and looking at that ground point. * 1966 Deville Convertible * 2007 Escalade ESV Black on Black * 1996 Fleetwood Brougham Black on Black V4P -Gone* 1983 Coupe Deville Street/Show Lowrider -Gone* 1970 Calais 4dr Hardtop GONE* 2000 Deville DTS - Silver with Black Leather and SE grille GONE* 1999 Seville STS - Pearl Red GONE Link to comment Share on other sites More sharing options...
CoupeDTS Posted November 17, 2010 Author Report Share Posted November 17, 2010 Well i kicked off the temp sensor harness and the passenger side fan came on. Since the fans work and the relays work it must be that sensor. $10 part but PITA to get to, as usual. * 1966 Deville Convertible * 2007 Escalade ESV Black on Black * 1996 Fleetwood Brougham Black on Black V4P -Gone* 1983 Coupe Deville Street/Show Lowrider -Gone* 1970 Calais 4dr Hardtop GONE* 2000 Deville DTS - Silver with Black Leather and SE grille GONE* 1999 Seville STS - Pearl Red GONE Link to comment Share on other sites More sharing options...
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