Fan Relay Question
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Instructor
Joined: Oct 2000
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From: Nashville, Tn. 37211 TN.
Fan Relay Question
I would like to know if any can tell me what the green/white stripe and blue wires control on my '85 fan relay. I can only asume they control the switch to turn on the fans. One coming from the ECM (temp) the other from the a/c.
What I am trying to do is trick the ECM into sensing the fan is on. I have a adjustable thermo sensor that bypasses the ECM but as soon as engine reaches operating temp the service engine light comes on because the ECM is not reaching the relay to tell the fans to come on because it has been disconnected. The service engine light will shut off when the temp drops below 185.
Can anyone help me with this? :confused:
[Modified by Camvette, 1:35 PM 8/9/2001]
[Modified by Camvette, 1:36 PM 8/9/2001]
What I am trying to do is trick the ECM into sensing the fan is on. I have a adjustable thermo sensor that bypasses the ECM but as soon as engine reaches operating temp the service engine light comes on because the ECM is not reaching the relay to tell the fans to come on because it has been disconnected. The service engine light will shut off when the temp drops below 185.
Can anyone help me with this? :confused:
[Modified by Camvette, 1:35 PM 8/9/2001]
[Modified by Camvette, 1:36 PM 8/9/2001]
Safety Car
Joined: Jun 2000
Posts: 4,870
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From: Long Island, NY
Re: Fan Relay Question (Camvette)
Ok, you have a couple of choices:
1. Get a custom chip to turn the fans on at some temp you chose. (maybe 180 degs?)
2. Install a manual fan switch to turn the fans on with a flip of a toggle switch (This is the method I use).
Vic
1. Get a custom chip to turn the fans on at some temp you chose. (maybe 180 degs?)
2. Install a manual fan switch to turn the fans on with a flip of a toggle switch (This is the method I use).
Vic
Instructor
Joined: Jul 2001
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Cruise-In III Veteran
Re: Fan Relay Question (Camvette)
This may or may not relate to your 85.... :confused: ...on the 89...I am assume you are referring to the coolant fan...not the aux fan...the green/white wire provides the ground path through the ECM to energize the fan relay....the other wire is black and goes to the fuse block (eng/ecm/fuse)....however :bigears ...my aux fan has the grn/wht and the blue... 
...the grn/wht goes to the fan temp switch, located on the left side of the block..behind the alternater...the blue wire goes to the fuse block noted earlier... :seeya
...the grn/wht goes to the fan temp switch, located on the left side of the block..behind the alternater...the blue wire goes to the fuse block noted earlier... :seeya
Thread Starter
Instructor
Joined: Oct 2000
Posts: 206
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From: Nashville, Tn. 37211 TN.
Re: Fan Relay Question (Camvette)
I really want to know if anyone knows how to bypass the cooling fan relay to trick the ECM into sensing the relay. There has to be a way by crossing the relay wiring. I don't need a chip or a lower temp sensor because my adjustable sensor works great for the track or street. :D
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Re: Fan Relay Question (Camvette)
Your question doesn't make sense. The ECM doesn't sense relays, it grounds the relay coil to turn on the relay when it gets info that the fan needs to run, such as a/c turned on, or coolant temp above 228 F. If you want to force the fan on, you can ground the gr/wh wire on the fan relay which will close the relay and turn on the fan motor.
Thread Starter
Instructor
Joined: Oct 2000
Posts: 206
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From: Nashville, Tn. 37211 TN.
Re: Fan Relay Question (Camvette)
Well I guess that answers my question. I thought the ECM could sense an open or closed circut. If this is true, then there must be another cause for my service engine light. It sets no codes and comes on when the temp rises above 185. It will shut off when the temp goes below 185.
Any one have any ideas? :chevy
Any one have any ideas? :chevy
