LT1-LT4 Modifications - 97 LT1 Cooling Issue. Please Help
11-04-2009, 09:02 PM
So ive read the umpteen amount of threads about the LT's and their overheating issues. Ive fixed all of my issues except for the fans. I still can not get them to come on unless the A/C is running. Here is what ive done so far, new water pump, thermo, coolant temp sensor, all three fan relays. Ive been to shbox.com and read the article, hooked up the scan tool the temp reads out fine, and im throwing codes 1641 and 1642 which i know are the fan relay control circuit 1,2 and 3. Ive pulled the PCM fuse to reset, still no go. Id really like to avoid putting the fans on a manual switch if i can but will do so if i have to. Any thing i am missing or suggestions?
P.S this all started after my water pump went out.
11-04-2009, 09:10 PM
Did you replace the Coolant Sensor on the Water Pump or the Head?
11-04-2009, 09:12 PM
The sensor on the water pump
11-04-2009, 09:14 PM
And did you replace it with the correct one?
11-04-2009, 09:18 PM
I believe so, a buddy of mine works at advanced so i go there use the discount. They were out of the AC Delco, wont be in until friday so i grabbed the BWD. When i pulled the old one out it looked exactly the same and the plug matched with no problems.
heres the link for the sensor just incase
11-04-2009, 09:24 PM
Yea, that's it..
May have to do the Manual Switches if worse comes to worse..
11-04-2009, 09:31 PM
thats what i was afraid it would come to. Before this happened the only codes it was throwing was an o2 and EVAP. So i assume the fan relay control circuit codes i am gettin would be the issue, is that chasing wires to find a short? if thats the case then manual switch just got a lot more appealing. Not a fan of wire hunting
11-04-2009, 10:33 PM
Lots of LT1 Cars loose the capability to control the Fans..must be a fluke.
11-04-2009, 10:43 PM
Ive been reading up in some other threads on people who hot wire the fans to turn on the entire time the car is running, since im currently in fla and its hot 10 months out the year that sounds like a good idea, except for greatly reducing the life span of the fans. I cant seem to figure out exactly how to hot wire it though....
11-04-2009, 10:51 PM
What year is the car, is it a three relay or two relay system? It is not hard to troubleshoot at all, you either do not have your 12 volt switched to your relays or you are not getting signal from the pcm to toggle them or you have some bad relays. If I were you I would grab a test light and a multimeter and start putting in some leg work
11-04-2009, 10:54 PM
It is a 97, three relay system, I put all new relays in it this afternoon. I honestly wouldnt even know what to start testing? The relays? Or the senor from the water pump to the PCM. The Fans do come on when the AC is on...