what next
Thread Starter
Instructor
Joined: May 2005
Posts: 164
Likes: 0
From: Ann Arbor MI
what next
Well I have read everypost regarding overheating my 84 has a overheating problem I have replaced the sensor the fan relay,cleaned the radiator between the condensor put a new cap on checked the fuse but the fan will not come on any ideas what Next I also run power to the fan and it comes on so I don,t have a clue what to do next any ideas would be greatly appreciated
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 7
From: Tampa Florida
Too Cool!
The relay controls the "On/OFF" of the fan. The relay is closed when the ground leg of the relay's coil is grounded by the ECM. Check the wire for opens if none are found replace the ECM.
OR:
Figure out which wire is the ground wire that is opened and closed by the ECM. Cut this wire and attach a piece of wire to it and connect the other end of this same wire to a battery ground or other good grounding point. The fan will now "run" all the time when the key is in the "ON" position. This solution will work since the engine's thermastat controls the amount of water that will actually be cooled. You'll notice that your car will run much cooler since the fan has a head start on the cooling processes.
I've run this configuration for over 9 years with no problems.
OR:
Figure out which wire is the ground wire that is opened and closed by the ECM. Cut this wire and attach a piece of wire to it and connect the other end of this same wire to a battery ground or other good grounding point. The fan will now "run" all the time when the key is in the "ON" position. This solution will work since the engine's thermastat controls the amount of water that will actually be cooled. You'll notice that your car will run much cooler since the fan has a head start on the cooling processes.
I've run this configuration for over 9 years with no problems.
Thread Starter
Instructor
Joined: May 2005
Posts: 164
Likes: 0
From: Ann Arbor MI
The relay controls the "On/OFF" of the fan. The relay is closed when the ground leg of the relay's coil is grounded by the ECM. Check the wire for opens if none are found replace the ECM.
OR:
Figure out which wire is the ground wire that is opened and closed by the ECM. Cut this wire and attach a piece of wire to it and connect the other end of this same wire to a battery ground or other good grounding point. The fan will now "run" all the time when the key is in the "ON" position. This solution will work since the engine's thermastat controls the amount of water that will actually be cooled. You'll notice that your car will run much cooler since the fan has a head start on the cooling processes.
I've run this configuration for over 9 years with no problems.
OR:
Figure out which wire is the ground wire that is opened and closed by the ECM. Cut this wire and attach a piece of wire to it and connect the other end of this same wire to a battery ground or other good grounding point. The fan will now "run" all the time when the key is in the "ON" position. This solution will work since the engine's thermastat controls the amount of water that will actually be cooled. You'll notice that your car will run much cooler since the fan has a head start on the cooling processes.
I've run this configuration for over 9 years with no problems.
Thanks for the responce That is what i was thinking of doing I,m glad that there is no other complications
Instructor
Joined: Jul 2007
Posts: 174
Likes: 0
From: Toronto Ontario
The relay controls the "On/OFF" of the fan. The relay is closed when the ground leg of the relay's coil is grounded by the ECM. Check the wire for opens if none are found replace the ECM.
OR:
Figure out which wire is the ground wire that is opened and closed by the ECM. Cut this wire and attach a piece of wire to it and connect the other end of this same wire to a battery ground or other good grounding point. The fan will now "run" all the time when the key is in the "ON" position. This solution will work since the engine's thermastat controls the amount of water that will actually be cooled. You'll notice that your car will run much cooler since the fan has a head start on the cooling processes.
I've run this configuration for over 9 years with no problems.
OR:
Figure out which wire is the ground wire that is opened and closed by the ECM. Cut this wire and attach a piece of wire to it and connect the other end of this same wire to a battery ground or other good grounding point. The fan will now "run" all the time when the key is in the "ON" position. This solution will work since the engine's thermastat controls the amount of water that will actually be cooled. You'll notice that your car will run much cooler since the fan has a head start on the cooling processes.
I've run this configuration for over 9 years with no problems.
Last edited by trackman44; Aug 6, 2007 at 08:32 PM. Reason: 6 and 8 exhaust NOT 7 and 8
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 7
From: Tampa Florida
Actually the ECM does NOT control the fan relay in an 84 vette. There is a fan switch sensor located between #7 and #8 exhaust pipes on the passenger side head. You need to replace this sensor for the fan to turn on. But before you do this check to make sure the 3 Amp fuse in the fuse box is good. Also i had a problem similar to yours about overheating and it turned out the thermostat was stuck closed, so i replaced it and the car ran cooler after that.
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
Well,.....we know the fan motor is good, so....
To test the switch between 6 & 8, remove the wire and touch it to ground with the key "on". Fan should come on.
If it does, replace the switch. If not, it's time to start tracing wiring between the fan, relay, switch, fusebox, and every connector in between.
Does your fan come on when you switch the A/C on?
Time to get out the old factory service manual and start tracing wiring. And no, the ECM does not control the fan on the 84.
To test the switch between 6 & 8, remove the wire and touch it to ground with the key "on". Fan should come on.
If it does, replace the switch. If not, it's time to start tracing wiring between the fan, relay, switch, fusebox, and every connector in between.
Does your fan come on when you switch the A/C on?
Time to get out the old factory service manual and start tracing wiring. And no, the ECM does not control the fan on the 84.
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Intermediate
Joined: May 2007
Posts: 29
Likes: 0
From: wheeling west virginia
i had the same problem with my 84,i replaced every sensor relay and thermostat,i got a sensor from advanced auto that you put on the rad.its adjustable you can set it to what temp you want it to kick on and off.its working good so far it just till i can find the real problem,most likely a ground
it just till i can find the real problem,most likely a ground