Fan 2 cycles on and off then on then off.

[mrhurt73]

I finally got my LM7 running, just got the ECM flash on sunday. but when the engine heats up to fan 2 on setpoint it cycles on and off constantly.

my engine is a 2000 GMC 5.3L LM7 stock, but not using clutch fans, using dual electric fans run off the ECM.

now from the HP tuner software i can manually run each fan and it does fine.
so i am fairly sure the wiring is ok. it has to be a setting in the ECM.

any help would greatly be appriciated.