randybill

2000 Silverado 1500 5.3 with 2005 efans and factory 2005 efan harness. Using original pcm with 2002 OS #156.

Originally did the swap/conversion back in april of this year. Was able to command the fans on and off with HP tuners when I first completed the swap. Recently, I was in traffic at a stoplight and the efans didn't kick on as expected. That's when i started digging into the possible problem.

I command the fans on/off (with HP tuners) and i can hear each relay click but fans don't kick on. Fans are good - tested by running direct from battery. Used a volt meter to check voltage at fan connectors- 12vdc when fans are commanded to "ON" with HP.

I also reflashed back to the original OS and was still not able to command fans on and off. Then re-flashed back to 2002 156 OS.

What am I missing? Not sure if it's hardware or software at this point. I have not pulled each relay to verify but since I was getting battery voltage at connector I assume the relays and fuses are fine.

randybill

UPDATE: fans are working again. bad ground it appears. Originally had the ground at the horn mount bracket on the passenger side. drilled a new hole in the frame horn and remounted ground. viola! fans working again.

i'm curious why this was a good ground and the fans worked originally with horn ground then it stopped working? odd. worked tonight just taking the truck on a test drive.

thought i'd update. I hate finding a thread that has the 'same' problem i do with no updates or solutions.