2004tr

Symptoms :-
On start up from cold, fan 1 comes ON after 2 seconds and stays on even
though fan setting has been set to come ON at 209 & OFF at 200.

So disconnected BLUE 42 from PCM so that fan 1 does not come on at all.

Leaving engine to idle and build up temp so that fan 2 cuts in at 220, which it does but then stays ON continualy even though the temp has gone below its OFF setting of 210

Any thoughts please as to why Fan 1 comes on too soon and Fan 2 does not turn off.

Trevor
Cobra Replica , 2002 LS1/T56 with S&P headers, HP Tuners
No A/C , No emissions control

jay_99z

iTrader: (5)

fan relay?

2004tr

No, that was my first check, it is working just as it should and wired correctly.
The blue 42 signal from the pcm earths after 2 seconds -
the relay is doing exactly as it is told.

Trevor

2004tr

Problem solved for anyone who has the same problem in the future :-
I have now also removed AC clutch connections at PCM as well as AC request signals. Engine now starts without immediate fan initiation.
RED 14,17,18 & 43 removed

wws699

iTrader: (3)

did you have your heat selector switch in the defrost mode? that will bring the fan on at start up i think