Coolant Temp Sensor
Thread Starter
Racer
Joined: Feb 2014
Posts: 275
Likes: 14
From: Gahanna, Ohio
Coolant Temp Sensor
I just replaced my temp sensor (passenger side) with the upgraded 2 wire one. My understanding was that for the 84 vette one wire spliced into the sensor wire, while the other went to ground. I grounded one wire on the exhaust manifold (maybe not the best place as it was rusty?) and when I turned on the power my dash went nuts, everything flickered etc and car wouldn't even crank. I unplugged the connector and car started right up with no issues. What have I done wrong? can't seem to find much help on this on the net. Thanks
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
I would go and get oem. The one on the pass side is for the fan and it should not affect the car. Now the one in front is for fuel mixture(whether the car is hot or cold) and the one on the drivers side is for the temp reading for digital dash display, The one in front could make your car not start.
Race Director
Joined: Aug 2007
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From: Whitefish Falls Ontario
St. Jude Donor '08-'09
Melting Slicks
Joined: Jun 2013
Posts: 3,065
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Thread Starter
Racer
Joined: Feb 2014
Posts: 275
Likes: 14
From: Gahanna, Ohio
No, it is sensor for the fan to turn on, it's a one wire, the new switch is supposed to be better but it goes from a single wire to 2 wire. I need to know what to do with the extra wire. This is for the temp sensor on passenger side of engine by dipstick.
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
Just get the right switch the technology can't be worth the better switch.
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
the single wire sensor in the head on pass side should be for the temp gauge. Not sure where you are getting your information but I have never seen a 2 wire senson replace a single wire sensor. The one infront of the engine mounted by the thermostat housing is a 2 wire sensor. This sensor feeds the temp to the ECM so it can adjust the aire fuel mixture timing ect. I have not seen it all but if I were you I would go back and get the correct sensor and hope you did not fry something
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Safety Car
Joined: Sep 2004
Posts: 3,953
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From: Mission Viejo CA
You guys with non '84's shouldn't try to help if you don't know '84's! This just confuses the issue! '84's are a special breed, and are quite different than later cars. The temp sensor for the fan is a normally open switch that closes at about 200+/- degrees. If the sensor you installed has any resistance when cool, you've got the wrong part. The fan in an '84 is not controlled by the ECM.
Your description of everything going crazy makes no sense, unless you have a short in the fan motor circuit. Does the fan run when you connect the one wire at the temp sensor to ground (key on, engine off)?
Your description of everything going crazy makes no sense, unless you have a short in the fan motor circuit. Does the fan run when you connect the one wire at the temp sensor to ground (key on, engine off)?
Last edited by Hot Rod Roy; Mar 2, 2014 at 02:48 AM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The coolant temperature sensor the dash uses is on the driver's side.
Here's a diagram for the cooling fan circuit (stolen from vetteoz -- I know he won't mind ;-):
Thread Starter
Racer
Joined: Feb 2014
Posts: 275
Likes: 14
From: Gahanna, Ohio
You guys with non '84's shouldn't try to help if you don't know '84's! This just confuses the issue! '84's are a special breed, and are quite different than later cars. The temp sensor for the fan is a normally open switch that closes at about 200+/- degrees. If the sensor you installed has any resistance when cool, you've got the wrong part. The fan in an '84 is not controlled by the ECM.
Your description of everything going crazy makes no sense, unless you have a short in the fan motor circuit. Does the fan run when you connect the one wire at the temp sensor to ground (key on, engine off)?
Your description of everything going crazy makes no sense, unless you have a short in the fan motor circuit. Does the fan run when you connect the one wire at the temp sensor to ground (key on, engine off)?
Thread Starter
Racer
Joined: Feb 2014
Posts: 275
Likes: 14
From: Gahanna, Ohio
I am thinking there is a lot of misinformation on this. The correct name for the part is coolant fan sensor (or engine coolant temp switch) , I called it just a temp sensor (that name seems to go to the one on the intake). Temp sensor is the 2 wire for ECM on manifold, this fan sensor is on pass head. I thought I read that you could upgrade the fan sensor to a 2 wire unit, but I bet the person meant upgrade the ECM unit sensor. I am going to order the correct part and start over.
Last edited by Ahnenerbe; Mar 3, 2014 at 06:04 PM.
Instructor
Joined: May 2012
Posts: 201
Likes: 0
From: co
all you have to do is provide a gound to the relay for the fan. thats what the original switch does.
not sure why a 2 wire would be any better but one wire on a 2 wire switch would still have to be grounded. when it closed it would complete the ground circuit through the other wire. original grounds directly into head when it closes. not sure how making another connection is going to help.
Melting Slicks
Joined: Dec 2009
Posts: 2,230
Likes: 284
I used a 2 wire switch to control my fan, the reason is the aftermarket heads had 1/2 ntp threads instead of 3/8 ntp. I couldn't get the oem switch to work well with a pipe adaptor. Plus the switch I installed kicks the fan on at 210 or so. Bad thing though, its a ford part.