Jesse Burton

alright guys before i begin thanks for the help in advance.

i have a 99 ls1 powered z28six 6 speed well my cooling fans are not turning off ever even with the keys not in the ingintion. replaced all 3 relays and still have the problem im pretty good with wireing diagrams and this isnt makeing any since even if im having a sensor problem the fans still shouldnt run with key off right ? help please

GaryDoug

As far as I know, you are correct in that the fans should not run with the ignition switch off. Here is what I would do:

First of all, are you sure there hasn't been a switch installed to force the fans to run all the time the switch is on? It is not that rare for the owner to install such a switch.

If no such added switch is found:

Remove all 3 fan relays.
If the fan(s) still run, check for a short of the light blue or white wires at the fans to battery voltage. Very unlikely ... I know.
If the fan(s) do not run, plug in the relays one at a time (ignition off) until the fan(s) runs again. Then check for a short-to-ground of either the dark blue (for fan 2 or fan 3 relay) or dark green (for fan 1 relay)wires.
If no short-to-ground is found, you may have a shorted PCM, again very unlikely.

Jesse Burton

thanks man after reading your reply I went back and check everything I found that Indeed have a switch it's a 3 way switch where in one position the fans ran in low in the middle postition it's ran in normal mode and in the 3rd postion both fans ran in high I only messed with the switch while the car was running and always put it back in the middle because I didn't think it did anything I must have bumbed it way day getting out of the car thanks for the help