Fan randomly coming on.
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
Fan randomly coming on.
So I’ve had this issue with my cooling fan coming on whenever it wants. I do have a custom chip that I tune myself. I’ve tried changing my tune making another bin file from a fresh tune and still has this problem. Looking at the log my temp looks fine. Not reading too high or jumping around or anything. But I did notice the fan request status is going nuts. I really don’t think it’s the coolant sensor. But am suspecting the ECM. I checked the ECM board for any burn spots and didn’t see any. I’ve seen one before with fan problems have a burn spot on the board. Anyway here’s a video. 89 corvette
Last edited by kitttransam; Apr 30, 2022 at 06:01 PM.
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
What values do you have entered for all the "scalars" in the BIN? Fan engagement depends on speed, temp, and A/C on/off. There's also "Min Fan 1 Time On". On mine, the later is set to 15s.
I know the ECM gets it's own temp from another sensor than the dash. I don't know where it monitors speed. My ZF6 has a sensor IIRC. It might do what you're showing if it can't determine speed.
I know the ECM gets it's own temp from another sensor than the dash. I don't know where it monitors speed. My ZF6 has a sensor IIRC. It might do what you're showing if it can't determine speed.
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
Well I was looking at my fan settings in the bin. I did notice that the values under the A/C on was a bit lower than the values for A/C off. I watched the temp on the laptop. Looks like it is going off the values for A/C on even though A/C is off. I changed the bin and made the values match on both sets of scalers. Maybe it was getting confused?? Whatever is causing it. It’s intermittent. Earlier the fan came on after starting car not even close to the fan temp and it was going on and off. Was going to try something from the FSM just a bit ago and the fan was working normal.
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
I know in the ARAP bin the fan speed table is all maxed that’s how I left it. Also not to long ago I had a problem with my A/C clutch staying engaged. Was caused by a bad bearing and the magneto was ground down causing it to ground itself and stay engaged. I thought that was causing my fan problem before I fixed that. or did it cause something else to go bad?
Instructor
Joined: Oct 2000
Posts: 190
Likes: 10
From: southern new jersey
Had a similar problem with mine at it was the ECM..... very sporadic. At times it would flash the SES light but not set a code. Again very sporadic. After checking with the FSM I replaced the ECM. All is well now.
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
Yeah the ecm is definitely the main thing I would suspect. In fact in the fsm the only troubleshooting table close to that is for it running all the time. Says to pull the green wire from C1 and if it goes off go to the ecm troubleshooting section. In fact over a year ago I bought an 87 trans am gta. For some reason the wire for the fan switch was grounded to run all the time. I fixed that and fan would not work right. Pull ecm and had a nice burn spot on the board. Replaced with an extra I had and was all good. Unfortunately I don’t have an extra one laying around anymore.
