Overheating
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
before you fabricate something try moving those intercooler mounts to the top side of the cradle rail and see how that affects the intercooler mounting... when I had the smaller intercooler in my car I want to say I had those brackets on the top side and I didn't have any of the fitment issues you're having
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
crap, wish I had seen it sooner... well I think you know what the culprit is now so I'm sure you can figure out a way to fix it
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
I sure hope so. I'm going to buy some poster board on the way home from work today to use as a template for boxing in the sides and top cover. I'm hoping to secure the top and sides using pushpins like they use for everything on the car to make it easy to remove if need be. I'm going to also see about getting a 4" (thick) rubber or abs plastic piece to cover the flat aluminum piece under the radiator to catch as much air as possible and incase it hits the ground it will give a little like the stocker.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
I'm pretty sure I found my problem, lol. This is why I would make a horrible mechanic. I decided to use hptuners to run the fans on low and high with the engine and trans cooler fan off so I could hear a different pitch from the fans. Instead I got this. Bad relay?
And this is my gap now from the radiator to the IC.
And this is my gap now from the radiator to the IC.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
Whelp, relays weren't the problem as they still click when high speed is enabled. I commanded the high speed on again and removed the plugs to both fans and the relays still clicked. My favorite kind of issue, electrical.
I checked all 3 relays and fuses. All fuses are good and I swapped the 3rd relay with another one in the fuse box to no avail. Guess it's time to start going through the service manual and tracing wires.
Here's what one of the relays looked like and the other 2 looked fine.
Is there a certain area I should investigate first?
I checked all 3 relays and fuses. All fuses are good and I swapped the 3rd relay with another one in the fuse box to no avail. Guess it's time to start going through the service manual and tracing wires.
Here's what one of the relays looked like and the other 2 looked fine.
Is there a certain area I should investigate first?
Last edited by danieloneil01; Sep 19, 2014 at 09:16 PM.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
Just for ***** and giggles I checked the voltage on relay #44.
High speed off (only showing where I got voltage on)
13.4v on #86
High speed on (only showing where I got voltage on)
0.8v to 1.8v on #87a
13.4v on #85
12.8v to 13.4v on #86
Pulled the codes
28-TCS
C1221H
C1222H
C1248H
40-BCM
B2592H
AO-LDCM
U1064H
A1-RDCM
U1064H
High speed off (only showing where I got voltage on)
13.4v on #86
High speed on (only showing where I got voltage on)
0.8v to 1.8v on #87a
13.4v on #85
12.8v to 13.4v on #86
Pulled the codes
28-TCS
C1221H
C1222H
C1248H
40-BCM
B2592H
AO-LDCM
U1064H
A1-RDCM
U1064H
Last edited by danieloneil01; Sep 19, 2014 at 10:08 PM.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
85 and 86 are the coil contacts. You should have ~13V on one and ground on the other in order to get contact closure.
87a should have voltage on it and 30 should be the fan (load) itself and it's ok if 87a and 30 pins are reversed in responsibility, with 87a taking on the load.
It sounds like there's not sufficient voltage to close the relay contacts and keep them closed. I'd have to pull the schematic to see if the PCM is throwing hot or ground to operate the relay. I've seen pins in that block go bad before and that may be the case here. You can move to an external relay and bypass that one all together to solve your problem if you ever decide you're tired of digging for the source of all this. Let me know if you decide to pursue that and need help with it and I'll post something up.
87a should have voltage on it and 30 should be the fan (load) itself and it's ok if 87a and 30 pins are reversed in responsibility, with 87a taking on the load.
It sounds like there's not sufficient voltage to close the relay contacts and keep them closed. I'd have to pull the schematic to see if the PCM is throwing hot or ground to operate the relay. I've seen pins in that block go bad before and that may be the case here. You can move to an external relay and bypass that one all together to solve your problem if you ever decide you're tired of digging for the source of all this. Let me know if you decide to pursue that and need help with it and I'll post something up.
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Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
I checked the high speed fan (dark blue wire with high speed enabled) at the PCM and was getting 1.5v. I tried grounding the right fans ground to a good ground source (battery) and still clicked. So now I'm off to checking all connections (relays and fans) with the voltmeter for high speed operation.
I have a service manual that has the wiring schematic.
Also, the post above yours was with the relay off for each test. This time it will be with them connected using a thin wire so the relay can be in place during test.
If I can't find the problem I'll just have it when the low speed turns on it's actually the high speed and just set the high speed temp operation to 284*. And how do you pull enough slack out of the fuse block to check the connections? I can get maybe 2" off the block and that's it.
I have a service manual that has the wiring schematic.
Also, the post above yours was with the relay off for each test. This time it will be with them connected using a thin wire so the relay can be in place during test.
If I can't find the problem I'll just have it when the low speed turns on it's actually the high speed and just set the high speed temp operation to 284*. And how do you pull enough slack out of the fuse block to check the connections? I can get maybe 2" off the block and that's it.
Last edited by danieloneil01; Sep 20, 2014 at 01:14 PM.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Man I'd just wire the fans directly to the alternator thru two HD 30 amp relays and use the factory power wires to the fan to trigger the relays... Use thick gauge wire for everything. You'll likely get more voltage to the fans to make them run faster and more consistent..
Who gives a **** if the low speed works, I'd just run em on high all the time... Truth be known, I've never noticed if mine runs at two different speeds..I know the come on exactly at 178* as per HPT but... not sure if its high or low..
I'll probably wire mine direct before next summer.. Just have to find out which factory wire is the correct trigger for the relay...(positive signal or neg signal to run the relay).
You'll be chasing this **** forever in the factory wiring harness and fuse box...
These cars are wiring anomalies...
Who gives a **** if the low speed works, I'd just run em on high all the time... Truth be known, I've never noticed if mine runs at two different speeds..I know the come on exactly at 178* as per HPT but... not sure if its high or low..
I'll probably wire mine direct before next summer.. Just have to find out which factory wire is the correct trigger for the relay...(positive signal or neg signal to run the relay).
You'll be chasing this **** forever in the factory wiring harness and fuse box...
These cars are wiring anomalies...
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
How can I just jump it off the the low speed relay to enable the high speed relay? I tried it but only the driver side goes on high while the passenger side doesn't come on. I have the schematic but I'm a ****ing idiot to this ****. I wished in the service book it also had what pin for the relay, 85 or 87, etc. I tried going off the voltage with the key to on and off to determine which was which but it didn't match up following the schematic. Also my high speed relay is very loose when it's connected to the fuse block.
On the 3 relays for the fans what is what on the relay pins? I know which one is 87a since it's the only one with 5 pins.
On the 3 relays for the fans what is what on the relay pins? I know which one is 87a since it's the only one with 5 pins.
Last edited by danieloneil01; Sep 20, 2014 at 02:37 PM.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
Man I'd just wire the fans directly to the alternator thru two HD 30 amp relays and use the factory power wires to the fan to trigger the relays... Use thick gauge wire for everything. You'll likely get more voltage to the fans to make them run faster and more consistent..
Who gives a **** if the low speed works, I'd just run em on high all the time... Truth be known, I've never noticed if mine runs at two different speeds..I know the come on exactly at 178* as per HPT but... not sure if its high or low..
I'll probably wire mine direct before next summer.. Just have to find out which factory wire is the correct trigger for the relay...(positive signal or neg signal to run the relay).
You'll be chasing this **** forever in the factory wiring harness and fuse box...
These cars are wiring anomalies...
Who gives a **** if the low speed works, I'd just run em on high all the time... Truth be known, I've never noticed if mine runs at two different speeds..I know the come on exactly at 178* as per HPT but... not sure if its high or low..
I'll probably wire mine direct before next summer.. Just have to find out which factory wire is the correct trigger for the relay...(positive signal or neg signal to run the relay).
You'll be chasing this **** forever in the factory wiring harness and fuse box...
These cars are wiring anomalies...
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
The mystery to solve is if the oem fan triggers are pos or neg.... Meaning are the fans hot all the time and the ground is cycled on and off or vice versa...
A volt meter at the pig tail at the fan should pinpoint what is cycled...Then use that wire to trigger the aftermarket relays..
I'm gonna be measuring the voltage at my fans soon, and if I don't have a solid 13.5v min going to them, I'm gonna wire them directly to the alt with thick gauge wire and use HD relays, triggered by the oem fan power or ground wire...(whichever is determined to be the cycled source)
As for all your factory relay/harness/fuse box questions, I can't help you...
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Here is the Bosch 50 amp relay/circuit breaker I used on my 71' for my Lincoln MK8 fan...Also an additional 30 amp relay that triggers the big relay when the AC comes on... So this fan is triggered by a temp switch in the radiator, the pressure switch on the AC comp and I have a manual switch for the track. This is all with 8 ga wiring. This setup works flawlessly and this car never runs over 185* with the AC on...This on an iron headed big block in a tight engine compartment.
I will be wiring something very similar up on the Z06 to the fans if I deem the factory wiring/relays are not conveying enough volts to the fans.
I will be wiring something very similar up on the Z06 to the fans if I deem the factory wiring/relays are not conveying enough volts to the fans.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
I guess removing the relays to many times has ruined the terminals. Now when I go to insert them back in they just drop in without any pressure. I added some solder to #44 terminal (5 pin relay) and it seats in there nice. But when I command the low fans to come on they do but if I move the relay at all, the driver side goes to high speed and the passenger side turns off.
Wonder if I could find someone local to do this. I'm so tired of working on this thing. Just have them on high speed all the time works for me now.
Wonder if I could find someone local to do this. I'm so tired of working on this thing. Just have them on high speed all the time works for me now.
Last edited by danieloneil01; Sep 20, 2014 at 04:49 PM.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
IF you are using the factory power wire to the fans as the trigger to the aftermarket relays, it should still cycle as it would from the factory, only it would be at full power...no low/high sequence.
The mystery to solve is if the oem fan triggers are pos or neg.... Meaning are the fans hot all the time and the ground is cycled on and off or vice versa...
A volt meter at the pig tail at the fan should pinpoint what is cycled...Then use that wire to trigger the aftermarket relays..
I'm gonna be measuring the voltage at my fans soon, and if I don't have a solid 13.5v min going to them, I'm gonna wire them directly to the alt with thick gauge wire and use HD relays, triggered by the oem fan power or ground wire...(whichever is determined to be the cycled source)
As for all your factory relay/harness/fuse box questions, I can't help you...
The mystery to solve is if the oem fan triggers are pos or neg.... Meaning are the fans hot all the time and the ground is cycled on and off or vice versa...
A volt meter at the pig tail at the fan should pinpoint what is cycled...Then use that wire to trigger the aftermarket relays..
I'm gonna be measuring the voltage at my fans soon, and if I don't have a solid 13.5v min going to them, I'm gonna wire them directly to the alt with thick gauge wire and use HD relays, triggered by the oem fan power or ground wire...(whichever is determined to be the cycled source)
As for all your factory relay/harness/fuse box questions, I can't help you...
Based on that post I can just splice C2 to C1 (or use a jumper wire at the relays???) to get them to run in high speed when low speed is activated? I still haven't figured out the relation of the relays to the schematic to even try this.
NEVERMIND, this turns the fans to high mode even with the key to off.
Last edited by danieloneil01; Sep 20, 2014 at 07:03 PM.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
So I've thought about this. Would this work and I can keep the high speed from coming on with hptuners. But something tells me this is to easy and maybe the relay and power wire can't take the extra load?
Last edited by danieloneil01; Sep 21, 2014 at 09:26 AM.
Thread Starter
Drifting
Joined: Apr 2011
Posts: 1,801
Likes: 1
From: Tulsa Ok
Before I go full retard and cutting wires I'm going to see if the problem is the fuse block since #43 relay will not lock into place and if you were to hold it upside down it would fall out. Here's a shot of one of three wire distribution blocks under the fuse block.
Top left is where the 5 pin relay (#44) is and below that is the 4 pin relay (#43).
That looks good to me and now it's time to separate the fuse block if it's possible., If I break oh well, I'll buy a new one.
Top left is where the 5 pin relay (#44) is and below that is the 4 pin relay (#43).
That looks good to me and now it's time to separate the fuse block if it's possible., If I break oh well, I'll buy a new one.
Last edited by danieloneil01; Sep 21, 2014 at 12:59 PM.