Fans not coming on.
the PCM commands the fan on, only under certain conditions. the most common is when coolant gets over 226°, or the AC is running and you are doing less than 30mph.
so when parked and AC is on if your fans don't come on then
1) see if the fans actually work. easiest way i guess is to pull the fan relay out and jump the two leads, and see if the fans work. if they don't then trace the wires to the fans and check the grounds. worst case you have bad fan motors, but that's unlikely.
2) if the fans work then on passenger side of car is the wiring harness going to pcm. you'll want to probe the green and blue wire in one of the connectors to see if the pcm is commanding the fans to go on. the pcm will ground the green wire for low speed fans, and both the green and blue for high speed. if the pcm doesn't, then either you have a bad circuit in the PCM and would need a new PCM to make the fans work again.... or you can rig up a switch and turn them on manually or get a temp sender to make them come on.
https://ls1tech.com/forums/general-m...ion-issue.html
so when parked and AC is on if your fans don't come on then
1) see if the fans actually work. easiest way i guess is to pull the fan relay out and jump the two leads, and see if the fans work. if they don't then trace the wires to the fans and check the grounds. worst case you have bad fan motors, but that's unlikely.
2) if the fans work then on passenger side of car is the wiring harness going to pcm. you'll want to probe the green and blue wire in one of the connectors to see if the pcm is commanding the fans to go on. the pcm will ground the green wire for low speed fans, and both the green and blue for high speed. if the pcm doesn't, then either you have a bad circuit in the PCM and would need a new PCM to make the fans work again.... or you can rig up a switch and turn them on manually or get a temp sender to make them come on.
https://ls1tech.com/forums/general-m...ion-issue.html
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the PCM commands the fan on, only under certain conditions. the most common is when coolant gets over 226°, or the AC is running and you are doing less than 30mph.
so when parked and AC is on if your fans don't come on then
1) see if the fans actually work. easiest way i guess is to pull the fan relay out and jump the two leads, and see if the fans work. if they don't then trace the wires to the fans and check the grounds. worst case you have bad fan motors, but that's unlikely.
2) if the fans work then on passenger side of car is the wiring harness going to pcm. you'll want to probe the green and blue wire in one of the connectors to see if the pcm is commanding the fans to go on. the pcm will ground the green wire for low speed fans, and both the green and blue for high speed. if the pcm doesn't, then either you have a bad circuit in the PCM and would need a new PCM to make the fans work again.... or you can rig up a switch and turn them on manually or get a temp sender to make them come on.
https://ls1tech.com/forums/general-m...ion-issue.html
so when parked and AC is on if your fans don't come on then
1) see if the fans actually work. easiest way i guess is to pull the fan relay out and jump the two leads, and see if the fans work. if they don't then trace the wires to the fans and check the grounds. worst case you have bad fan motors, but that's unlikely.
2) if the fans work then on passenger side of car is the wiring harness going to pcm. you'll want to probe the green and blue wire in one of the connectors to see if the pcm is commanding the fans to go on. the pcm will ground the green wire for low speed fans, and both the green and blue for high speed. if the pcm doesn't, then either you have a bad circuit in the PCM and would need a new PCM to make the fans work again.... or you can rig up a switch and turn them on manually or get a temp sender to make them come on.
https://ls1tech.com/forums/general-m...ion-issue.html
reply
man this was very helpful, i appreciate your preciseness. i know the basics of the testing but i just got this car and to not have to look up the wiring diagram is a blessing .
What is the car doing.
Is it getting hot at idle and fans not coming on?
If AC is not on the gauge will get to around the 230 mark before fans come on.
If you aren't familiar with LS' thats normal cycle on temperature and the car is not hot or working abnormally. These motors are designed to run hot and guys coming from old school stuff loose their mind if they are unfamiliar with modern LS' and always' think they are running hot when they are stone normal to factory spec temp.
Is it getting hot at idle and fans not coming on?
If AC is not on the gauge will get to around the 230 mark before fans come on.
If you aren't familiar with LS' thats normal cycle on temperature and the car is not hot or working abnormally. These motors are designed to run hot and guys coming from old school stuff loose their mind if they are unfamiliar with modern LS' and always' think they are running hot when they are stone normal to factory spec temp.
