Camaro Zone Forums banner

LT1 PCM fan control issues

2K views 6 replies 4 participants last post by  the_y_guy 
#1 ·
I wanted to try and get some other opinions on what could be going on with my cooling fans...

Two weeks ago I was driving the car and I barely noticed the temp gage skyrocketing in time to pull over and spray coolant all over the place and overheat like crazy. After cooling down and re-filling I realized that my fans were not coming on (dual electric LT1 stock fans). I also noticed that the fan relay socket was melted slightly.

This past weekend I replaced the wiring down near the fans and the connectors that plug into the fans (previously my wiring had not been weatherproof as I had forgone the proper connectors. Some of the terminals had burning evident, however both fans still work great with power.

I replaced the relay, checked that my power and ground wires were properly connected and healthy, and tested everything out. No luck.

The PCM would not ground the relay no matter what temp the sensor provided, with the temp sensor unplugged, with the ALDL pins jumped, etc.

(for reference, i have both fans on one relay set to come on at around 200 F off of the low temp pin A11 red pcm connector)

So thinking I was clever I reflashed my PCM to control the fans from pin A12, the secondary fan pin for high temp/speed. Now, the fans come on with ignition power, AKA the PCM is constantly grounding that pin.


My best guess is that during whatever current/voltage event melted my relay socket, I managed to fry the circuit in my PCM that handles pins A11 and A12, and they are now permanently open (A11) and grounded (A12).

Any other ideas? As it sits now my fans run as soon as the key is turned, which beats no fans, but still isn't ideal. I am considering installing a manual switch to control the relay.

~Steven
 
See less See more
#2 ·
I would do the manual switch at least to give a temporary fix. Why was it overheating in the first place though?

Sent from my Z796C using Camaro Zone mobile app
 
#3 ·
Have you tried getting another PCM? I know its not ideal but just wire everything right and swap PCMs.

Sent from my SPH-L720 using Camaro Zone mobile app
 
#4 ·
I would rather not drop 150 bucks for another PCM. My plan is to re-wire with a relay per fan, and run them both off of a new thermal switch. Planning to install it on the pass. side where old gen I engines have temp senders. Looking at a 200 F on and 185 F off switch, and additionally a manual over-ride switch in the dash.

What caused the car to overheat in the first place was that the fans werent coming on at all because of this wiring issue.
 
#5 ·
I completely understand however of you have an issue with the PCM begining to fail than other issues may arise.

Sent from my SPH-L720 using Camaro Zone mobile app
 
#7 ·
I had the exact same problem with my 96 z28. I bought a manual fan control switch online from SLP for about $60-$70 (you could probably find a different brand for cheaper). Took me about 2-3 hours to install and whenever the temp starts to go higher than usual or I am at a red light or something I just flip it on. Most have 2 fan setting, a low and high. I would highly recommend it, was a fast and easy fix. Below is the link where I bought mine from.
http://www.slponline.com/product/63011--1993-2002-Camaro-Firebird-V6-V8-Fan-Control-Switch.html

Sent from my SM-G900V using Camaro Zone mobile app
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top