Hi all ! looking for info, I have a 91 1le z28 (5.7 auto). bought a hypertech cooling fan switch, went to go install it in the right cylinder head and noticed that there was no wire going to it, looked everywhere to no success. I went on alldata.com and looked at a wiring diagram for standard cooling ,single fan it is a 1le, it has no a/c and a single fan. On the wiring diagram with standard cooling it shows no cooling fan switch , just the green with white wire going directly to the ecm,which leads me to believe that the fans are triggered through ecm , and uses the coolant temp sensor input to the computer to monitor coolant temp.Can anyone tell me if my diagnostics are right or if I have to have the ecm reprogrammed,remember this is a 1991 1le z28 5.7 auto and the car is original with 80k and has never been modified, I am the second owner and know the original owner, thanks in advance for any info.

 

Your right the memcal will need to be reprogramed with a no ac , tpi car. If you need some assistance with reprograming send me a pm

 

thanks for the confirmation, what I did this morning was got into the engine harness on the pass side and found the green with white stripe cut it at where it loops behind the strut tower and soldered and shrink sleeved it to the hypertech harness and changed to the hypertech fan switch and low and behold the fan operates just like hypertech says.I think this will not hurt anythink becuse it is a ground circuit but either way I capped it with shrink. What are you r thoughts on this mod?

 

That will work

 

Thanks for the advice Rich.

 

That's weird that it only has 1 fan.......

 

1LE’s only had one fan because they didn't have a/c. The Hypertech fan switches don't work without modification because they control the secondary (a/c) fan. It says "for dual fan models only" in the application notes.

 

That makes sense but if your setting a car up for road racing I'd think 2 fans would be better.

 

At road racing speeds the fans aren't operating. I would think that the single shroud-less fan would be less of an airflow restriction than the dual set-up. I don't think Chevy actually gave it any thought either way though. No a/c equals single fan, 1LE or not. They didn't even think it was necessary to equip the 1LE with a wonder bar.

 

Very true. GM did some weird stuff. 1 fan is prolly less weight also.
The dual fans don't have a shroud either.
I think the wonder bar was just a temp fix until the steering box frame got internally re-enforced.
There is a road course in Joliet IL that has some slower speeds in spots, doubt 2 fans would be needed unless something is really wrong tho.

 

I read the thread because I have the same problem. I need your assistance to reprogram my car. Can you please help?

 

Send me a pm I’ll try to help