Posted: Sun Jan 01, 2012 9:10 pm Post subject: Temp/Fan Issues
I just got done doing the Head Gaskets on my '05 3400. Made a few performance enhancements (P&P Heads, P&P Exhaust Manifolds.) Also replaced a leaking Water Pump and went back to a 180F Tstat over the 160F I had before.
Anyway, Engine is running great. I ran into a new issue of the fans not kicking on until ECT gets to be 212F. First couple of of times the fans would run for a little while and it would get it back to about 185/6F and then cut off. Now they will only get it down to 200/1F.
I fired up HPTuners as I knew I would have to change the start and stop temps anyway. I changed it from Start @ 170F and stop at 160F to start at 190F and Stop at 180F.
I have ensured all the air is properly bled from the system, enough coolant etc etc. Fuses look good. I will note the fans were squeaking for quite some time prior to the build and the car has been sitting for 6mo.
Anyone got any ideas of where else to start troubleshooting?
I'm guessing your driver side (primary) fan motor died. Mine did the same thing and made a lot of noise before it finally died.
Check for continuity between the positive and negative on the fan with the harness off...if you don't have any continuity, your fan motor is most likely shot. The good thing about the 04-05 is that you can replace just the motor without having to buy the whole shroud and assembly and everything.
For a temporary workaround (and to troubleshoot), change the temp for the secondary (passenger side) fan to turn on at the lower temp. At least that way you won't overheat. I did that for about a month or two before finally swapping mine out.
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Okay, so as an update I decided to go the dumb route and throw money at it. I replaced all of the cheap parts. Replaced all three fan controller relays, ECT Sesnsor, changed PCMs just to make sure it wasn't faulty.
The fans still turn on at random temps for random periods of time, never settling at a specific temp. Always turning on in high
I was playing with the tuner and found the VCM Controls and commanded the fans to run. They ran fine in Low and ran fine in High when I commanded them on.
The only thing I can think of is that there is a wiring issues. All fuses have been verified.
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