Has anyone encountered this Fan Relay problem?
Thread Starter
Racer
Joined: Jan 2011
Posts: 275
Likes: 2
From: Tucson Arizona
Has anyone encountered this Fan Relay problem?
I'm just getting back to trying to fix my weird overheating problem. I've been over most everything and found, quite by accident, that the Fan 1 relay has activation power constantly. Even with the key off. There is nothing in my service manuals that addresses this particular occurrence. Or I just couldn't find it in there...
I'm thinking that this is a PCM fault as I can't find a wiring problem. I'm hoping that someone on here has an idea of what might cause this. My next idea is to tear the entire wiring harness apart from the relay to the PCM just to see if there are any bare wires shorting. Otherwise it is time to buy a replacement PCM and hope that it really is the problem.
I've been contemplating just stripping the bitch and parting her out on a street corner. Argh....
lol
I'm thinking that this is a PCM fault as I can't find a wiring problem. I'm hoping that someone on here has an idea of what might cause this. My next idea is to tear the entire wiring harness apart from the relay to the PCM just to see if there are any bare wires shorting. Otherwise it is time to buy a replacement PCM and hope that it really is the problem.
I've been contemplating just stripping the bitch and parting her out on a street corner. Argh....
lol
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Pull your DIC codes and see if anything shows up. Not sure if this issue would even throw a code but not at home.
Also, disconnect the battery for several minutes and see if the issue goes away. Strange things can sometimes be corrected by a "reboot".
Also, disconnect the battery for several minutes and see if the issue goes away. Strange things can sometimes be corrected by a "reboot".
Drifting
Joined: Sep 2009
Posts: 1,719
Likes: 4
From: cinnaminson n.j.
St. Jude Donor '14
4DRUSH is correct. The PCM controls the grounding of the relay coils. If you remove the relays, key on, you should have power on 2 terminals and ground on 1 as long as the engine is cool. The 4th terminal is grounded by the PCM to activate the fans as needed.
Once you have done this you'll know if you have a problem. If you get 2 grounds on any on the relays, unplug the PCM and recheck. If you still have 2 grounds you have a short.
Once you have done this you'll know if you have a problem. If you get 2 grounds on any on the relays, unplug the PCM and recheck. If you still have 2 grounds you have a short.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
The comment about "bare wires shorting" seemed to indicate The Mountain Kat understands the PCM grounds the relay coil.
But maybe he could elaborate on what he means by activation power because the COOLFAN1 or Relay 45 coil always has power. The coils on Relay 43 and 44 are ignition switched.
But maybe he could elaborate on what he means by activation power because the COOLFAN1 or Relay 45 coil always has power. The coils on Relay 43 and 44 are ignition switched.
Thread Starter
Racer
Joined: Jan 2011
Posts: 275
Likes: 2
From: Tucson Arizona
Sorry guys for starting this thread and then disappearing. I have been involved in a major remodeling project in my home.
You're correct about this. I found the problem when I was getting exasperated and leaned on the COOLFAN1 relay with my bare arm. It was *hot*. Temperature-wise. I thought that I was being ditzy and left the key on so I looked in and yes the keys were on the console.
I remembered that I had a problem several times, after the overheating problem started, with the fans continuing to run after I turned off the key. I figured that the relay went bad and replaced it. This did not help the overheating but it did stop the run-on problem. Now it seems that the problem that I have now could have been initiated by the bad relay.
You're correct about this. I found the problem when I was getting exasperated and leaned on the COOLFAN1 relay with my bare arm. It was *hot*. Temperature-wise. I thought that I was being ditzy and left the key on so I looked in and yes the keys were on the console.
I remembered that I had a problem several times, after the overheating problem started, with the fans continuing to run after I turned off the key. I figured that the relay went bad and replaced it. This did not help the overheating but it did stop the run-on problem. Now it seems that the problem that I have now could have been initiated by the bad relay.
The comment about "bare wires shorting" seemed to indicate The Mountain Kat understands the PCM grounds the relay coil.
But maybe he could elaborate on what he means by activation power because the COOLFAN1 or Relay 45 coil always has power. The coils on Relay 43 and 44 are ignition switched.
But maybe he could elaborate on what he means by activation power because the COOLFAN1 or Relay 45 coil always has power. The coils on Relay 43 and 44 are ignition switched.
Thread Starter
Racer
Joined: Jan 2011
Posts: 275
Likes: 2
From: Tucson Arizona
Well I got down under Yvette again and pulled the PCM. Sure as hell there was a bent pin touching to the next pin causing a short. I carefully straightened the pin and reassembled things. No more codes and the FAN1 relay is operating correctly. ie; not activated when the key is off. I might get a chance to go for a drive to see if she still over-heats. I expect so as I haven't found any reson yet for the over-heating.
Leave it to my luck that no0one s=else has ever had this problem. Jeez...
Leave it to my luck that no0one s=else has ever had this problem. Jeez...
Sorry guys for starting this thread and then disappearing. I have been involved in a major remodeling project in my home.
You're correct about this. I found the problem when I was getting exasperated and leaned on the COOLFAN1 relay with my bare arm. It was *hot*. Temperature-wise. I thought that I was being ditzy and left the key on so I looked in and yes the keys were on the console.
I remembered that I had a problem several times, after the overheating problem started, with the fans continuing to run after I turned off the key. I figured that the relay went bad and replaced it. This did not help the overheating but it did stop the run-on problem. Now it seems that the problem that I have now could have been initiated by the bad relay.
You're correct about this. I found the problem when I was getting exasperated and leaned on the COOLFAN1 relay with my bare arm. It was *hot*. Temperature-wise. I thought that I was being ditzy and left the key on so I looked in and yes the keys were on the console.
I remembered that I had a problem several times, after the overheating problem started, with the fans continuing to run after I turned off the key. I figured that the relay went bad and replaced it. This did not help the overheating but it did stop the run-on problem. Now it seems that the problem that I have now could have been initiated by the bad relay.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski