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I have an 88 camaro that I picked up last summer and am chasing down electrical gremlins after the rebuild I did in the winter. Now that its hot out (I live in NC so 100+ during peak summer) having fans is an absolute must. The problem im having is that the relay keeps burning out. When I got the car the relay was bad so I replaced it, only for the fan to instantly turn on in any powered key position and buzz violently against the firewall. Any ideas? Can this just be a bad coolant sensor telling it its running at a billion degrees constantly?
This is out of the 1988 Firebird manual so I hope it is useful.
If your car is equipped with air conditioning then the fan pressure switch for the A/C compressor will turn on the coolant fan if it is stuck closed.
This is out of the 1988 Firebird manual so I hope it is useful.
If your car is equipped with air conditioning then the fan pressure switch for the A/C compressor will turn on the coolant fan if it is stuck closed.
I appreciate it. I have a non a/c car, but this is helpful nonetheless. It's looking like now after I replaced the relay it won't even buzz anymore. It just clicks once when I plug the fan in. Took it for a drive after to see if itd kick on and nothing
I think this is not an ecm controlled fan unlike tpi and 3.1 fur a cylinder head temp switch than activates the fan relay. Sorry wish I had a accurate schematic
My apologies, the original post did not specify and my mind was on a previous post on V8s.
The gist of the story remains the same but the picture is different for a V6. Here you go.
My V6 fan does not run until the engine warms up, car stopped, at idle, and it never comes on when the car is moving as natural air flow is enough to keep her cool.
I'm a little confused though, as the cooling fan is on the radiator not the firewall, or are you talking about the cabin fan?
I just looked the 1227302 should be wired like this. It’s odd a cts fails showing hot they usually fail reading a negative degree at the computer. If the ecm is triggering the relay it could be a faulty ecm. That’s a cheap ecm to find used on eBay. But with the schematic above easy to see if ecm is triggering the relay.
My apologies, the original post did not specify and my mind was on a previous post on V8s.
The gist of the story remains the same but the picture is different for a V6. Here you go.
My V6 fan does not run until the engine warms up, car stopped, at idle, and it never comes on when the car is moving as natural air flow is enough to keep her cool.
I'm a little confused though, as the cooling fan is on the radiator not the firewall, or are you talking about the cabin fan?
The relay against the firewall would sit and buzz the second I put the key into any position. While it was buzzing the fan would actually kick on, but constantly. Not when the car got to temp like it should. Now, the relay only makes a clicking noise when I plug the fan in. Otherwise, it does nothing at all. The fan wont kick on, even kick on after a long drive. Again, i appreciate the new schematic. Ill try to look into it tomorrow.
Last edited by MCamaro28; Jul 31, 2025 at 09:14 PM.
Is this the rad fan relay that is chattering?
Does your car have a redundant cooling fan switch that may have failed closed?
CIRCUIT OPERATION
V6 VIN S, V8 VIN F and V8 VIN 8
The Coolant Fan is controlled by the Electronic Control Module (ECM). In the V6 VIN S, the Coolant Fan is also controlled by the Redundant Cooling Fan Switch. When the ECM grounds the 335 circuit, the Coolant Fan Relay is energized and battery voltage is applied to the Coolant Fan. If the ECM fails (V6 VIN S), the Redundant Cooling Fan Switch will ground the 335 circuit and energize the Coolant Fan Relay. The ECM will ground the Coolant Fan Relay when the Coolant Temperature Sensor indicates the coolant temperature is greater than 106O C (222O F) or when the AIC Control Head pressure is greater than 233 psi (1600 kPa) and the vehicle speed is less than 40 mph.
Is this the rad fan relay that is chattering?
Does your car have a redundant cooling fan switch that may have failed closed?
CIRCUIT OPERATION
V6 VIN S, V8 VIN F and V8 VIN 8
The Coolant Fan is controlled by the Electronic Control Module (ECM). In the V6 VIN S, the Coolant Fan is also controlled by the Redundant Cooling Fan Switch. When the ECM grounds the 335 circuit, the Coolant Fan Relay is energized and battery voltage is applied to the Coolant Fan. If the ECM fails (V6 VIN S), the Redundant Cooling Fan Switch will ground the 335 circuit and energize the Coolant Fan Relay. The ECM will ground the Coolant Fan Relay when the Coolant Temperature Sensor indicates the coolant temperature is greater than 106O C (222O F) or when the AIC Control Head pressure is greater than 233 psi (1600 kPa) and the vehicle speed is less than 40 mph.
Yes, it appears to have both switches and it is the cooling fan relay on the right. I did replace the original relay and main fan switch located on the rear of the pass. Head last summer trying to get the fans to work but never touched this one. Maybe youre my saving grace! Im not too handy with a multimeter but ill try and see what the Redundant switch is spitting out.
I just looked the 1227302 should be wired like this. It’s odd a cts fails showing hot they usually fail reading a negative degree at the computer. If the ecm is triggering the relay it could be a faulty ecm. That’s a cheap ecm to find used on eBay. But with the schematic above easy to see if ecm is triggering the relay. 
