yea, off... and i know this because i have monitor lamps on the dash that indicate when one or both fans are on. it seems to come on at the right temp (200), cools down, but stays running anyways. if i start out cold in the morning on a long trip, it will never come on, except for a few when i stop for gas, then it will go back out. if i'm in normal busy traffic during the day, it will come on sitting at a light, but then never go out after the car is in motion again and cooled down. the other day, same thing, but coming back in the evening when i stopped for gas, it came on for a few and went off and stayed off. and conditions (driving habits and outside temp) were the same as before i stopped for gas. makes no sense, other than maybe the switch is bad and not cutting off when it should? don't see where it could be a relay, cuz the fan(s) won't come on til that ground to the relay(s) is complete, and that is where i get my indication on the dash from...

 

This is probably not much help, but the workshop manual for my '88 Firebird (also running the L98 5.7 TPI) suggests if the main coolant fan stays on, you should do tests relating to the auxiliary fan, to see whether it has gone open circuit, has a faulty relay or a faulty wiring circuit. I assume from what you say that your auxiliary fan is probably working, so that complicates things ! Maybe the coolant temp sensor has drifted out of its normal adjustment and is telling the ECM that the engine is hotter than it really is.
I've just fixed an overheating problem (neither fan was starting up and the engine was overheating and boiling up at low speeds or when idling) by replacing the sensor.

 

if i recall, the primary fan is only activated by the fan switch in the head and/or when the a/c pressure switch closes. it only tells the ecm that that circuit is grounded, whereas the ecm grounds the circuit for the aux fan. i disconnected the a/c switch for a while (a couple of road trips), but didn't seem to be the problem, so leads me to the fan switch in the head as most logical.

 

The impression I have from my Pontiac workshop manual is that it's the auxilliary fan (passenger side) is the one which is associated with the request from the air con or when the coolant temperature exceeds about 230 degrees

My wiring circuit shows the main fan switches on when the ECM receives the appropriate temperature info (222 degrees) from the sensor on the front of the inlet area. That's located below the main air intake hose from the air filter and the hot water plumbing to the intake. There are two devices located there, the other one being the cold start switch, but the coolant sensor is the one closer to the driver's side.

 

well, it is the passenger side fan that i'm speaking of and that is the one that tends to stay on. i suppose i failed to mention, too, that the switch i have in there is a lower temp switch (on @ 200, off @ 185). the other fan is grounded by the ecm when it receives the temp input from the CTS. apparently it hasn't gotten hot enough for that one to come on, other than once when i had the defrost on, but it didn't stay on.